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Sednon probe, quodpedesomncsbifculcospinxit: & candam tabellis tarn mult is con- ftruxit, EADEM TABULA &t A G N V S dcpingit aftacum xn. pedum, qitideuoratur a mcnftro mart- no (Imill rhihoccroti. A HISTOKY OF GBUSTACEA EECENT MALACOSTBACA BY THE REV. THOMAS E. E, STEBBING, M.A. FORMERLY FELLOW AND TUTOR OP WORCESTER COLLEGE, OXFORD AUTHOR OF 'THE NATURALIST OF CUMBRAS* 'THE CHALLENGER AMPHIPODA ' ETC. WITH NUMEROUS ILLUSTRATIONS LONDON KEGAN PAUL, TRENCH, TRUBNEK & CO. LTD. PATERNOSTER HOUSE, CHARING CROSS ROAD 1893 (The rights of transtation and of reproduction are reserved) PBEFACE THE ambition of this volume is that it shall be one to which beginners in the subject will naturally have re- course, and one which experienced observers may willingly keep at hand for refreshment of the memory and ready reference. An attempt has been made in it to bring the reader face to face with the vastness of the theme, to show him how variously it may engage the human mind, and to give him a groundwork of information as to the objects to be examined, with a side glance at the literature that has discussed them. It is not very generally known that the species of Crustacea extend to a number of several thousands, and that some of these species people parts of the ocean in enormous swarms. Of some of the groups the general character is familiar to every one, but there are also groups of which most persons either know nothing or have not the least idea that they belong to the Crustacea. The beginner, therefore, will have provinces of a new world opened to his exploration. There is curiosity to be gratified. The sporting instinct will discover many an unexhausted territory. In the manners and customs VI PEE FACE of the creatures there is much to afford entertainment, and almost every new observer finds something singular to relate. In examining the structure both external and internal r whether in new species or in those that have been long established, the acutest powers of observation may be trained and profitably employed. Moreover, the highest ingenuity is excited and finds scope in the effort to explain the meaning of the facts observed. For, judging by dis- coveries already made, we are warranted in supposing that, down to the finest hair, every detail of every organism has its motive and meaning. Nor need man despair of finding out something for his private and personal benefit while investigating the physiology of a shrimp. It is needless to insist that a hundred volumes such as the present would not suffice to discuss the subject in all its bearings, since a hundred volumes would be but a small fraction of what has been already written upon it, and the incessant stream of publications widens and deepens as it flows. By the references made to some of the most recent and to some of the most important authorities, the student will be guided in general to adequate lists of literature. In consulting these bibliographical notices he will be perhaps as much amazed by the multitude of writers and writings as at first by the multitude of the genera and species of the Crustacea themselves. He will be led to consider it not unreasonable that the present volume should have been content to deal with one half of the entire class, leaving the other half for a future occasion. PREFACE V1L He will recognise by a perusal of the mere titles of what has been written, that no manual of this size could cope with all the branches of the subject, without the certainty of becoming a dry and repulsive catalogue. Even in what has been here laboriously put together the gentle reader is requested to remember that definitions are like the sermon which the preacher was forced to deliver, but to which, he reminded his hearers, they were under no sort of compulsion to listen. A time conies to the student when he scans every word of a definition with eager interest, but till then it will do him no harm to pass it over with cursory eyes and a light heart. In a volume of the International Series it would have been inappropriate to devote to the British fauna more than its proportional space, but I have thought that it would be neither unfair nor uninteresting to mention at least the names of all the British species, so far as it has been possible for me to collect them from and correct them by the latest and best authorities. One personal matter remains to be noticed. It was long the intention of Dr. Henry Woodward, of the British Museum, to publish in this Series a ' History of Recent and Fossil Crustacea.' The continual pressure of other engage- ments has prevented him from accomplishing the con- genial task. That, nevertheless, the results of his un- rivalled knowledge of the extinct forms will sooner or later be gathered into a compendium for general use should be taken for granted. The other materials which he had collected for his purposed work, relating principally to the characters of the living organism, are still in reserve- Vlll PEEFACE for the service of a future volume. In the meantime the production of the present book was entrusted to my hands at his express desire. A circumstance so honourable to myself and so well fitted to inspire an initial confidence in my readers, it would, I think, be false modesty to con- ceal. My best thanks are due to Dr. Woodward for his friendly and favourable opinion of my capacity ; they will be best paid if my performance has succeeded in de- serving it. THOMAS R. R. STEBBING. TUNBBIDGE WELLS, February 17, 1892. CONTENTS Chapter I. Classification of Crustacea in outline . . II. "Where to find specimens . . . .12 III. On giants and dwarfs . . . .24 IV. On the Crustacean segments and their appendages 32 V. Crabs ; their tribes, legions, and families . . 50 VI. The great eatable crab and its allies . . 55 VII. The land-crabs, and others of the same tribe . 78 VIII. On the ' sharp-snouted ' crabs, and some of their manners and customs .... 104 IX. On the tribe called Oxystomata or Leucosiidea . 123 X. The anomalous crabs .... 133 XI. Hermit-crabs, lobsters, and shrimps; their tribes, legions, and families .... 146 XII. Borrowers, and their kindred . . . 180 XIII. The warty Scyllarus and the spiny lobster, or crawfish ...... 191 XIV. The Norway lobster, the common lobster, and the crayfish ...... 199 XV. Small tribe of the Stenopidea . . .211 XVI. Branchial system, development, and range of the Penaeidea ..... XVII. A surprising multitude of shrimps and prawns . 224 XVIII. The Schizopoda ; their branching feet ; their fami- lies ; their luminosity .... 256 XIX. The burrowing Squillids, and their puzzling pelagic larv* . . 279 XX. A concise history of the Cumacea . . . 291 ? r ^ 1 0w O . ^ X CONTENTS Chapter Page- XXI. Tribes and families of the Isopoda ; the claw-bear- ing tribe ...... 314 XXII. Isopoda with a caudal fan, a vast and varied tribe . 330 XXIII. The tribe with a valve-bearing tail . . . 369 XXIV. Tribe of the Asellota ; including strange shapes and anomalous limbs .... 376 XXV. New tribe of the Phreatoicidea, from wells and mountain-streams ..... 388 XXVI. Parasitic Isopods ; their singular habits and trans- formations ...... 392 XXVII. Woodlice and other terrestrial Isopods . . 420 XXVIII. The Amphipoda conspicuous by their absence . 436 Index ..... 437 TABLES OF CLASSIFICATION The class Crustacea . . . . . .49 The suborder Brachyura . . . . .54 The suborder Macrura ...... 148 Affiliation of the larvae of the Squillidae . . . 290 Distinctive characters of Cumacean families . . . 312 The suborder Isopoda ...... 314 Synopsis of the Cymothoid group .... 340 Genealogy of the Epicaridea ; their Crustacean hosts. . 393 Genealogy of the Entoniscidae ..... 405 Genera of the Oniscidse ..... 426 Genera of the Arrnadillididse . . . . 433 LIST OF ILLUSTEATIONS. PLATE I. To face p. 25. Page Lobster devouring a man, and Rhinoceros Whale devouring a lobster. Gesner PLATE II. To face p. 84. Platyonichus iridescens, Miers. Challenger Brachyura . 67 Gecarcinuslagostoma, Milne-Edwards. Challenger Brachy lira 84 Calappa depressa, Miers. Challenger Brachyura . . 124 Cheliped of Calappa depressa .... 124 Leucosia australiensis, Miers. Challenger Brachyura . 127 PLATE III. To face p. 95. Eriocheir japonicus, de Haan. With separate figures of the pleon of male and female, and of the chelae of the female and young male. De Haan PLATE IV. To face p. 110. Platymaia Wyville-Thomsoiii, Miers. Challenger Brachyura 110 Naxia hystrix, Miers. Challenger Brachyura . . 116 Lambrus intermedius, Miers. Challenger Brachyura . 121 Hippa talpoida, Say. Adult female. S. I. Smith, . . 150 Second zoea stage of Hippa talpoida. S. I. Smith . . 150 Last zoea stage of Hippa talpoida. S. I. Smith . . 150 Xll LIST OF ILLUSTRATIONS Page- Catapagurns Sharreri, A. Milne-Edwards, in Epizoanthus americanus, Verrill. S. I. Smith .... 168 Catapagurus Sharreri removed from the polyp-colony. S. I. Smith PLATE V. To face 2). 137. Latreillia valida, de Haan. A female specimen, with separate figure of the head from below, flanked on the left by dorsal views of the male head and pleon, and on the right by dorsal views of the female head and pleon. De Haan PLATE VI. To face p. 153. Lithodes histrix, de Haan. A male specimen, with separate figures of the right chela and of the pleon, the latter shown in one view armed with its spines, in the other denuded of them. De Haan PLATE VII. To face p. 169. Birgus latro (Linnaeus). Desmarest . . . .156 Tylaspis anomala, Henderson. Challenger Anomura . 166 Pylocheles spinosus, Henderson. Challenger Anomura . 169 Porcellana longicornis (Linnaeus). Early larval form. Sars 172 Uroptychus insignis, Henderson. Challenger Anomura . 178 Third maxilliped of Uroptychus insignis Under surface of Uroptychus insignis, showing the pleon folded naturally Uroptychus gracilinianus, Henderson. Challenger Anomura 178 Ptychogaster Milne-Edwards!, Henderson. Chall. Anomura 178 PLATE VIII. To face p. 178. Lithodes maia (Linnaeus) Eupagurus Bernhardus (Linnaeus) Porcellana longicornis (Linnaeus) >- T .... . larval stage. Sars Galathea intermedia, Lmjeborg Munida rugosa (Fabricius) I End of pleon in the last LIST OF ILLUSTRATIONS xiii PLATE IX. To face -p. 186. Page Upogebia littoralis (Bisso). First post-larval stage. Sars . 186 Palinurus vulgaris, Latreille. Earliest larval form. Bate . 198 Nephrops norvegicus (Linnaeus). Second larval stage. Sars 202 Peteinura gubernata, Sp. Bate. Challenger Macrura . 220 Elaphocaris Dohrni, Sp. Bate. Challenger Macrura . 221 PLATE X. To face p. 190. Cheiroplatea cenobita, Sp. Bate. Challenger Macrura . 170' Telson and uropods of Cheiroplatea cenobita . . 47 Thaumastocheles zaleucus (v. "Willemoes Suhm). Bate . 189 Platybema rugosum, Sp. Bate. Challenger Macrura . 235 Atya sulcatipes, Newport. Bate .... 240 First trunk-leg of Atya solcatipes . . . 240 Telson and uropods of Atya sulcatipes . . . 240 Nematocarcinus undulatipes, Sp. Bate. Challenger Macrura, 250- PLATE XI. To face p. 211. Stenopus hispidus (Olivier). With separate figures show- ing the maxillae, maxillipeds, first and second pleopods, and plan of the branchial arrangements and proportions. Bate PLATE XII. To face p. 219. Hepomadus glacialis, Sp. Bate. Challenger Macrura Peraeon from below, showing the thelycum Epistome, mandible, lower lip, first maxilliped, and branchial plume in section LIST OF ILLUSTRATIONS PLATE XIII. To face p. 272. Page Notostomus perlatus, Sp. Bate. Challenger Macrura . 246 Eretmocaris longicaulis, Sp. Bate. Challenger Macrura . 255 My sis relicta, Loven. A female specimen in lateral view. Sars 272 ,, ,, Ventral view of the cephalo-thorax ., Ventral view of telsoii, with inner branch of each uropod The eye, and a section of the upper part of it Squilla scabricauda, Lamarck. Desmarcst . . . 284 In both the dorsal and ventral view the first maxilli- peds are drawn back behind the large second maxilli- peds, as otherwise they could not be seen Squilla empusa, Say. Late larval stage. S. I. Smith . 290 PLATE XIV. To face p. 338. Eaneognathia gigas (Beddard). Challenger Isopoda . . 338 The male, the female, and the first gnathopod of the male Neasellus kerguelenensis, Beddard. Challenger Isopoda . 381 Ischnosoma spinosuni, Beddard. Challenger Isopoda . 383 PLATE XV. To face p. 352. Cirolana borealis, Lilljeborg. The adult male. Hanseti . 342 Head from below, and mandible . . . 342 Nerocila Loveni, Bovallius. Bovallius . . . 352 Dorsal and ventral view ..... 352 eratothoa auritus (Bovallius). Bovallius . . . 354 Dorsal and lateral view of female ; dorsal view of male 354 PLATE XVI. 'To face p. 3S9. Phreatoicus typicus, Chilton. Chilton . . . 389 Second maxilla, second pleopod, telson, and uropod of Phreatoicus typicus Phreatoicus australis, Chilton. Chilton . . . 389 LIST OF ILLUSTKATIONS XV PLATE XVII. To face p. 397. Page a. Microniscus calani, Sars. Bars . . . 397 b. Cyproniscus cypridinae (Sars). A female (with a male in the normal position) affixed to the body of a Cypri- dina norvegica. The right valve of the host has been removed. Sars . 397 c. Adult ovigerous female of the Cyproniscus, detached, and viewed from above d. Younger female, not yet ovigerous, in lateral view e. Male, probably adult, with the anterior extremity carrying two root-like processes, and embedded in the skin of the Cypridina /. Larva in the last stage of development, seen from above PLATE XVIII. To face p. 414. Portunion rnsenadis, Giard, on Carcinus msenas (Pennant). Giard and Bonnier . . 407 Portunion Kossmanni, Giard and Bonnier, Giard and Bonnier ..... 408 Cancricepon elegans, Giard and Bonnier. Lateral view of female ; dorsal view of male and female. Giard and Bonnier . . . .413 Gigantione Moebii, Kossinann. Dorsal iand ventral view of female. Kossmann .... PLATE XIX. To face p. 425. Helleria brevicornis, von Ebner The head from above, the head and pleon from below ; the antenna ; mandible, lower lip ; first maxilla, second maxilla, maxilliped ; first leg ; rudimentary first pleopod with opercular plate of the second, stilet of the second pleopod, fourth pleopod showing the opercular plate broadside and edgeways, and the peduncle with the bran- chial plate ; uropod. Von Ebner a xvi LIST OF ILLUSTRATIONS ILLUSTRATIONS IN THE TEXT 1. 'The lady in the chair.' [Herbst] . . . 48 2. Ethusa mascarone (Herbst). [Herbst] . . .53 3. Corystes cassivelaunus (Pennant). [Herbst] . . 73 4. Gelasimus arcuatus, de Haan. [de Haan\ . . 89 5. Huenia proteus, de Haan, adult male, [de Haan] . 108 6. Huenia proteus, de Haan, young male, [de Haan] . 108 7. Huenia proteus, de Haan, female, [de Haan] . . 108 8. Chorinus aculeatus, Milne-Edwards. [Aiirivillius] . 115 9. Myra fugax (Fabricius). [de Haan] . ,. . 128 10. Dorippe japonica, von Siebold. [de Haan] . . 131 11. Eanina scabra (Fabricius). [de Haan] . . . 141 12. Zanclifer caribensis (de Freminville). [Henderson] . 144 13. Lomis dentata (de Haan). [de Haan] . . . 154 14. Spiropagurus spiriger (de Haan). [de Haan] . . 165 15. Porcellana longicornis (Linn.), young form. [Stebbing] . 172 16. Ibacus incisus (Peron). [Desmarest] . . . 194 17. Astacus arnericanus (Milne-Edwards), larval form. [8. I. Smith] ....... 204 18. Astacus americanus (Milne-Edwards), larval form. [S. I. Smith] . . . . . . .204 19. Astacus americanus (Milne-Edwards), larval form. [S. I. Smith] . . . . . . .204 20. Sergestes atlanticus, Milne-Edwards. The petasmata [Spence Bate] ...... 215 21. Procletes biangulatus, Spence Bate. [Spence Bate] . 254 22. Mysis relicta, Loven. First maxilla. [G. 0. Sars] . 272 LIST OF ILLUSTRATIONS xvil I'aRe 23. Mysis relicta, Loven. Second maxilla. [G. 0. Sars] . 272 24. Diastylis stygia, Sars. First maxilliped. [G. 0. Sars] . 297 25. Diastylis Goodsiri (Bell). Second maxilliped. [Hansen] 298 26. Diastylis Goodsiri (Bell). Female. [Hansen} . . 310 27. Diastylis Goodsiri (Bell). Female. [Hansen] . . 310 28. Eisothistos vermiforniis, Haswell. Male. [Haswell] . 334 29. Eisothistos vermiformis, Haswell. Female. [Haswell] . 334 30. Gnathia asciaferus (Hesse). [Hesse] . . - 338 31. Ceratocephalus Grayanus, Woodward. [Haswell] . 364 32. Eurycope gigantea, Sars. [Hansen] . . . 385 The names in italics indicate the sources from which the figures have been copied or adapted. The Brachyura of the Challenger were described by Mr. E. J. Miers, the Anomura by Dr. J. R. Henderson, the Macrura by the late Mr. C. Spence Bate, the Cumacea by Professor G. 0. Sars, the Isopoda by Mr. F. E. Beddard. The other pictorial authorities are Gesner's ' Historia Animalium,' Herbst's ' Naturgeschichte der Krabben und Krebse,' Desniarest's ' Considerations generates sur la classe des Crustaces,' de Haan's ' Crustacea ' in von Siebold's ' Fauna Japonica,' and various papers of modern date by G. 0. Sars, S. I. Smith, C. W. S. Aurivillius, H. J. Hansen, C. Bovallius, C. Chilton, MM. Giard and Bonnier, R. Kossmann, W. A. Haswell, and Victor von Ebner. For the text, as distinct from the illustrations, many other authorities would have to be named, but the text will speak for itself. As to the reproduction, on a scale suitable to these pages, of figures so numerous and so diversified from originals neither equal in merit nor uniform in style, I am indebted to Mr. James D. Cooper for the care and skill exhibited in carrying out a task of no mean difficulty. A HISTOEY OF RECENT CRUSTACEA THE MALACOSTRACA CHAPTER I OUTLINE OF CLASSIFICATION IT is conceivable that by origin all the animals of the globe belong to a single family. They now exhibit very great divergence. Between a star-fish and a crocodile, for ex- ample, the cousinship is obscure and remote. Yet almost all species may be included within a few principal clans, and these are united one to another by a small number of intermediate forms of life. For the whole series the de- tails of classification will vary with the increase of know- ledge. No system has yet been accepted as final. One, which is sufficiently good for our present purpose, dis- tributes animals among nine leading divisions. These are (1) the Protozoa, primitive animals, such as the Forarnini- fera and Infusoria ; (2) the Ccelenterata, in which the body- cavity serves alike for circulation and digestion, a tribe which includes sponges, corals, and jelly-fish ; (3) the Echinodermata or prickly-skinned animals, embracing the sea-lilies, star-fishes, sea-urchins, sea-cucumbers, and a B 2 A HISTORY OF RECENT CRUSTACEA wormlike genus called Balanoglossus ; (4) the Vermes or Worms; (5) the Artkropoda ; (6) the Mollusca, among which are the well-known oyster, snail, and cuttle-fish ; (7) the Molluscoidea, containing the mollusc-like lantern-shells, and the grouped animals of the Polyzoa, in some of which the so-called ' bird's-head ' organs amuse the observer ; (8) the Tunicata, the tunic-clad or mantled animals, com- prising the Ascidians, whether tough-coated or gelatinous, and the Salpte which roam the sea in alternate genera- tions solitary or connected in a chain ; (9) the Vertebrata, with 'the important classes of fish, amphibians, reptiles, birds, and mammals. It is with the central group of these nine that we are here concerned. So far as the name goes the Arthropoda are animals with jointed limbs. So far as the name goes, therefore, cats and dogs and vertebrates in general might belong to this division. But the name was given with reference not to the vertebrates, but to the vermes, for originally the worms and arthropods were included in a division called the Annulosa, animals of which the bodies contain several annuli, rings, metameres, somites, zonites, arthromeres, or segments, as they are variously called. These two sections of the Annulosa are now severed, and are distinguished by the circumstance that the one is, and the other is not, provided with jointed limbs.' The Arthropoda are defined as animals which have bodies composed of variously shaped segments ; which have jointed appendages attached to some at least of the segments ; which have (in general) a brain united to a ventral nerve-cord, or ganglionic chain, and which exhibit bilateral symmetry. None of the other divisions will be found to possess all these characters combined. For example, in the verte- brata the nerve-cord is dorsal, in the mollusca the body is unsegmented, in the vermes there are no jointed appen- dages. Instances, it is true, are to be met with of arthro- pods which do not themselves answer the requirements of the definition, instances in which the body is unsymme- trical or unsegmented, and in which there are no articu- DEFINITION OF THE CLASS lated limbs. But in all these instances there is a period of life when the creature possesses, though it subsequently loses, the characters which determine its place in classifi- cation. Under the Arthropoda are included five classes, two of which are of very prominent importance in the economy of the world. The five classes are the Crustacea, Pycno- gonida, Arachnida, Myriapoda, and Insecta. A sixth class, the Onychophora, is sometimes added for the sake of the peculiar genus Peripatus, but for the present it may be as well to give this the rank of an order among the myria- pods, a class represented by the familiar but unfavoured centipede. The Arachnida contain spiders, scorpions, mites, as well as some other less commonly known groups. The Pycnogonida (or Pantopoda), the sea-spiders, at one time included in the Crustacea and at another time in the Arachnida, have some remarkable peculiarities, inas- much as the ovaries of the female are found as a rule not in the trunk of the body, but in the thighs of the legs, and when the eggs are laid they are usually carried about not by the mother but in packets upon the oviferous feet of the male. The Insecta are so strikingly distinguished by the special number of their legs that this class sometimes receives the name Hexapoda, the six-footed animals. Beetles, bees, bugs, flies, fleas, moths, spring-tails, ear- wigs, grasshoppers, and gnats, in countless profusion people the globe, sometimes disputing possession with man him- self or rendering his life a burden, at other times offering him service direct or indirect of no mean value. It is in this class, and in this class only, that the present state of science reckons the number of species not only by scores of thousands but by hundreds of thousands, and even by millions. The class which stands nearest to the Insecta in the multitude of known species is that of the Crus- tacea, but the interval is so vast that, properly speaking, the Insecta are in this respect first with no second. Of the numerous definitions which have been given of the Crustacea, it will be safficient to quote two. According B 2 4 A HISTORY OF RECENT CRUSTACEA to one of these, they are ' AquaticArthropoda, which breathe by means of gills. They have two pairs of antennae, numerous paired legs on the thorax, and usually also on the abdomen.' This is compendious and useful. The statements clearly exclude all the other classes of the Arthropoda. They are also widely applicable among crus- taceans ; yet of these animals there are some which are not aquatic, some which have no gills, some which have not two pairs of antennae, and some in which the ' paired legs on the thorax ' are not numerous. A different definition was given by Professor Alphonse Milne-Edwards in 1860, according to which the class of Crustacea comprises ' all the segmented animals with bran- chial or cutaneous respiration, in which the body is pro- vided with jointed limbs, whether permanent or transitory.' The Insecta and Myriapoda breathe by means of the air- tubes called trachese; most of the Arachnida by means either of tracheae or pulmonary sa.cs known as fan trachese. From all these, therefore, the definition separates the Crustacea in a satisfactory manner, even though some terrestrial Crus- tacea combine tracheate with branchial respiration. There are, however, some subordinate members of the Arachnida, and the whole class Pycnogonida, in which the respiration is dependent on the surface of the body and not on any special organs. As it is only in recent years that the Pycnogonida have been constituted an independent class, it was no fault of a definition framed in 1860, that it included them among the Crustacea, to which they were then supposed to belong. They are in fact separated by many characters, one of which is the possession of a proboscis, which is supposed to have originated in the coalescence of the upper lip and the mandibles. So far as is known, they are all marine animals. On the other hand, those Arachnida which have surface-respiration are apparently all air-breathers. To meet all existing requirements, then, the definition of the Crustacea may be framed in the following manner : They are Arthropoda without terminal proboscis, with respiration branchial or cutaneous, the latter only aquatic. It is not to be expected that any legitimate definition OEIGIN OF THE NAME 5 of an extensive class will be largely descriptive, because many features of wide range and great prominence are likely to be missing in outlying and erratic members of the group, and these consequently have to be passed over unnoticed, in favour of less conspicuous, and of alternative,, or even of negative characters. The name Crustacea is a Latin word of old standing. Another and probably the original form of it is Crustata. The animals clothed in a crust, a covering of more or less flexibility, were distinguished by the ancients from the Testacea, in which the test, as in the example of an oyster- shell, is hard and rocky, and like a potsherd more ready to- break than to bend. Dr. Johnson was of opinion that if the terms of natural knowledge were extracted from Lord Bacon's works, few ideas in that branch of learning would be lost to mankind for want of English words in which they might be expressed. 1 Modern science would be much hampered by such a limitation of its verbal resources. Johnson's own dictionary during the last century does not recognise the substantive, a crustacean. The adjective, crustaceous, it thus defines : ' Shelly, with joints ; not tes- taceous ; not with one continued, uninterrupted shell. Lobster is crustaceous, oyster testaceous.' The same dic- tionary defines and illustrates the word crab as follows : ' A crustaceous fish. ' Those that cast their shell are, the lobster, the crab> the crawfish, the hodmandod or dodman, and the tortoise. The old shells are never found, so as it is like they scale off and crumble away by degrees. Bacon's Natural History. ' The fox catches crab fish with his tail, which Olaus Magnus saith he himself was an eye-witness of. Derham.' Shellfish, crayfish, and crawfish, are expressions still in use, although the term crab-fish is no longer in fashion. The uncritical ages had a tendency to regard as fish most animals which came out of the sea, and a story is told of a cook who persuaded her Hebrew mistress that a. sucking pig became for all practical purposes a fish by being mad 1 See A Dictionary of the English Language. Preface. Eighth Edition. 17U9 6 A HISTORY OF RECENT CRUSTACEA to run a few steps into the ocean and out again. With a similar effort of the scientific imagination, the illustrious Erasmus Darwin, when a schoolboy, excused himself for eating roast goose during Lent by the scriptural axiom that ' all flesh is grass,' and the goose therefore a species of vegetable. Ro far as the name Crustacea implies a covering of any considerable toughness, it is little applicable to some of the parasitic members of the class, but in general much more confusion than advantage follows from the dis- placing of long-established names in the effort after absolute accuracy. If we are never to use the scientific designation of a group unless it exactly applies to all the members of it, then what is to be done, one writer rather maliciously asks, in the case of the species called Homo sapiens ? A general though not a complete agreement prevails in regard to the external boundaries of the crustacean class. The proper mode of subdividing it and the arrangement of the subdivisions are subjects still open to much dis- cussion and dispute. Any final decision depends upon questions of genealogy which have yet to be answered. In the mean time four sub-classes may be accepted, under the names Gigantostraca, Malacostraca, Entomostraca, and Thyrostraca. The Gigantostraca, or giant-shells, are the oldest in known lineage, and, as the name implies, fore- most in the average of magnitude. They seem to be tending to speedy extinction. The Malacostraca include forms highest in development and of most direct value to mankind. The Entomostraca probably surpass the rest in multitude of individuals, if not also of species, but are the smallest in average size. The Thyrostraca, commonly called Cirripedia, though they fall short of the Entomostraca in numbers, excel them in bulk, and are even more remote in outward appearance from any general idea of a crusta- cean, such as the better known malacostracan lobster, or the crab fish, might suggest. The Greek word Malacostraca, meaning soft-shelled animals, is practically equivalent in sense to the Latin MALACOSTKACA 7 word Crustacea. Like that, it was originally adopted to distinguish such creatures as crabs and crawfish and prawns from such others as oysters and clams ; not be- cause of the absolute, but because of the comparative softness of their shells. Were reasons wanted for dis- placing the name, they would not be difficult to find. Many of the Malacostraca have shells harder instead of softer than those of some Mollusca. In some Malacostraca the integument has ceased to be of the nature of a shell, a parasitic habit having cancelled the need for such a defence. Moreover, the term suggests a false contrast with the neighbouring sub-class of the Entomosti-aca, in which as a rule the shells or skin-coverings are still softer. The name Thoracipoda, not open to any of these objec- tions, has been proposed by Dr. Henry Woodward. But against this it may be urged that, by many students of the Crustacea, the word thorax is not admitted as a proper technical term, and among others it is disputed whether the word, if admitted, should apply to three, to seven, to eight, or even to nine, of the crustacean segments. Retaining, therefore, the ancient, familiar, and suffi- ciently euphonious word Malacostraca, the subdivisions of this sub-class mav next be considered. Two orders tf have been* formed, named respectively the Podophthalma, or stalk-eyed, and Edriophthalma, or sessile-eyed, crusta- ceans. In the former the eyes are mounted upon stalks or peduncles, which are almost invariably movable ; in the latter they are in continuity with the general surface of the head, or, if raised above it, the ocular prominences are unjointed and immovable. That some species in both orders are blind, gives a certain vantage-ground for the disturbers of accepted names to follow their bent. These may also allege that the terms just explained have not been at any time in undisputed possession. The Podoph- thalma have also been called Decapoda, ten-footed, while the Edriophthalma have been called TetradecapSda, or fourteeii-footed, Crustacea. The second of these names has found but little favour, and the first has the dis- advantage that it would apply to some Crustacea that are A HISTOEY OF EECENT CRUSTACEA not podophthalmous, and does not apply to others tLat are. Instead of Podophthalma or Decapoda, Burmeister proposed Thoracostraca. To this, however, the objections already urged against Thoracipoda will apply, with the additional one, that the word has a termination which had been already employed in two, and has since been em- ployed in the third and fourth of the higher groups. Some purists correct the word Edriophthalma, in accord- ance with its derivation, into Hedriophthalma. They may correct on the printed page, but who can guarantee that they will have their cherished aspirate pronounced ? The stalk-eyed Crustacea are portioned out into four sub-orders: 1. The Brachyura, or short-tails, such as the edible crab; 2. The Macrura, or long-tails, such as the common lobster, prawn, and shrimp ; 3. The Schizopoda, or cleft -footed crustaceans, in certain points of structure so near to the prawns and shrimps that at least one author of eminence classes them among the Macrura ; and 4. The Stomatopoda, with feet converging about the mouth, crea- tures abundant in some waters, but rare in those that wash the shores of Great Britain. A fifth sub-order, the Anomura, or irregular-tails, has long been accepted, but modern classification is disposed to distribute its members, which include the hermit crabs and others of very curious habits, between the Brachyura and the Macrura, from which they may be supposed to have respectively diverged, yet without losing all trace of family connection. The sessile-eyed Crustacea are at present divided into three sub-orders, the Cumacea, Isopoda, and Amphipoda. The Cumacea seem to have entirely escaped the notice of the ancients, and among the moderns an accurate know- ledge of their singular structure is not too widely diffused. One of the genera earliest brought into notice received the name of Ouma, a wave, and from this was formed the de- signation Cumacea for the whole sub-order, which is exclu- sively marine. The Amphipoda, which are common in fresh as well as in salt water, were so named by the French naturalist Latreille, as having feet extending in all direc- tions, their limbs at the same time having much diversity ENTOMOSTEACA of form in correspondence with diversity of function. The Isopoda, or equal-footed animals, besides being found both in fresh and salt water, have more decidedly than the Amphipoda extended their range to the dry land. The name was invented by Latreille in ignorance of the great number of species since investigated in which the feet are strikingly unlike and unequal. Nevertheless the name may stand, just as a rose remains a rose even when it is not rose-coloured. To these three sub-orders some authors are disposed to add a fourth, the Tanaidea, while others, though agreeing to withdraw these animals from their old position among the Isopoda, would prefer to place them among the Amphipods. The need for the change in either direction has not yet been established. The Entomostraca, by their name, which literally means testaceous insects, bear witness to an era in classification when not only they but all other crustaceans were arranged among the Aptera or insects without wings. As the forms are multitudinous and very frequently microscopic, and as moreover crowds of the species have only been made known within recent years, it is not to be wondered at that the internal arrangement of this sub-class, like that of the preceding one, is still open on some points to discussion, although there is a fair amount of agreement as to the main lines of division. The method here followed dis- tinguishes three orders, the Branchiopoda, Ostracoda, and Copepoda. By Latreille the name Branchiopoda was ap- plied to the Entomostraca at large. It signifies branchial- footed, or animals in which the feet are in one way or another adapted to serve the purpose of respiration. This order is subdivided into four sub-orders. I. The Phyllo- carida, literally leaf-shrimps, derive their name from the laminar or leaflike expansions with which their legs are provided. 2. The Phyllopoda, the leaf-footed ones, owe their name to the same characteristic, although by other features they are distinguished from the Phyllocarida. None of the Phyllopods are marine, although a few inhabit brackish water or strong brine. 3. The Gadocera, which are so called from their branched antennae, occur chiefly 10 A HISTORY OF RECENT CRUSTACEA in fresh water, where they are common, but inconspicuous, and to the ordinary observer little suggestive of the crus- tacean type. 4. The Branchiura, represented by the carp- lice, are so designated from having a branchial tail which actively assists in the function of respiration. The Ostracoda, a title which might be interpreted as the testaceous Crustacea, may be easily mistaken for minute bivalve mollusca. Like the BranchiopSda they are divided into four sub-orders, the Podocopa, Myodocopa, Cladocopa, and Platycdpa, in which names words meaning feet, mus- cles, branch, and broad, are respectively compounded with the Greek word signifying an oar. The Copepoda point at once to a connection with the preceding order, inasmuch as there one of the sub-orders derived its name from words signifying a foot and an oar, while the Copepoda are indebted to the very same compo- nents, in the inverse order of an oar and a foot. The actual structure of the animals to some extent justifies this similarity of names, but in general appearance the Copepoda, not being shut up in two-valved shells, are widely different both from the Podocopa and the rest of the Ostracoda. Three sub-orders are formed : (1) the Gnathostoma, having the mouth well provided with jaws ; (2) the Pcecilostoma, in which the mouth varies ; (3) the Siphonostoma, having the mouth produced into a siphon or tube. The Gigantostraca are as rare as the Entoniostraca are common. They are divided into three orders, the Mero- stomata, Xiphosura, and Trilobita. Of these, the first and third are entirely extinct, so that the knowledge of them is derived only from fossil remains. The Merostomata have a name derived from two words, meaning a thigh and a mouth, this singular combination alluding to the no less singular fact that in these animals the mouth is surrounded by a group of limbs which are not only locomotive and prehensile, but also subservient to mastication. This peculiarity belongs likewise to the Xiphosura, or sword-tails, which are named from the long and sharp piece at the end of the body, their characteristic THYEOSTEACA 1 1 tail-spine. Some authorities hold that this order should be removed from the crustacean class to that of the Arach- nida. The name of the third order, the Trilobita, refers to the circumstance that they usually have the body divided by two longitudinal dorsal grooves into three lobes. They were extremely abundant in bygone ages, and the natu- ralists of the Challenger were continually in hopes that they might obtain a living specimen or two from hitherto xmexplored abysses of ocean. But extinction appears to have done its work with great thoroughness upon this order. The last of the sub-classes consists of the Cirripedia or curl-footed animals. The alternative name Thyrostraca, meaning ' valve-shells,' has the merit of agreeing in ter- mination with the names of the, other three sub-classes. But it must be admitted that if it is objectionable to call the whole group cirripedes when some have no cirri, it is equally inappropriate to call them all ' valve-shells ' when some have no valves. It is a triumph of the present cen- tury in minute investigation and comparative anatomy, that has withdrawn the Cirripedes from the zoophytes, worms, and molluscs, among which, at various times, the older naturalists placed them, and that has given them henceforth an .undoubted position among the Crustacea. They may be divided into five orders, or the first two, the Pedunculata and the Operculata, may be grouped together as divisions of an order hitherto designated Thoracica, in which the part called the thorax is provided with cirri. The Abdominalia have the cirri only on the so-called abdomen. The Apoda are without cirri, being, as their name implies, footless. Lastly, the Ehizocephala are a parasitic set, which send rootlike filaments, into the bodies of their hosts. 12 A IIISTOKY OF RECENT CRUSTACEA CHAPTER II- SPECIMENS Collecting To study adequately any branch of natural history, it is essential to have specimens. Many exemplary forms of Crustacea are not difficult to obtain. Representatives of the two highest orders in the group, the crab, the lobster, the prawn, the shrimp, are exceedingly familiar, as these creatures lie .on the fishmonger's board, or are brought to O / O table for food. When the eatable parts have been con- sumed or otherwise removed, the debris is still of value for mental nourishment. This refuse may be made to yield more profit and pleasure than many a costly collec- tion which can only be viewed intact. By carefully separating the constituent parts of the head, the trunk, and the tail, in each of the crustaceans above mentioned, and comparing them piece by piece, the beginner will be able to give himself a cheap but invaluable lesson. He will be surprised at first to detect likenesses in the corre- sponding parts of animals externally very distinct, and afterwards he will be surprised at the differences in the corresponding parts of animals which he has learned to regard as closely connected. As his range of study widens, he will find relationships established between forms which, to any one unacquainted with the intermediate links, must seem to have absolutely nothing in common. For instance, while examining the gills of a lobster, he may chance to observe some small orange-coloured specks, and may rightly conjecture that these are parasitic animals. But it is scarcely conceivable that any amount of genius would BREAKFAST-TABLE ZOOLOGY 13 enable a man to discern, from a comparison of the lobster alone with its entomostracan parasite, that they are alike crustaceans, which is, nevertheless, known to be the case. In a dishful of prawns it may often be noticed that one or two of the finest have the head swollen on one side, as if the creature were suffering from a face-ache. There is no special reason to suppose that the prawn thus affected is suffering any great inconvenience. It is merely lending the shelter of its carapace to a family of isopod crustaceans. Comfortably ensconced in the bulging cheek-piece will be found a misshapen animal of no inconsiderable size, in general laden with innumerable eggs, and accompanied by a far smaller partner, the father of the brood, symmetrical in form, and retaining some of the freedom of movement which belongs to the young when first hatched, but which the mother has. entirely resigned. Thus the zoology of the breakfast table will supply examples of three very dis- tinct orders. These examples are none the less curious because they happen to be common. Any one who is content to examine them with care will thereby lay a simple and solid foundation for all subsequent study in the realm of carcinology. The novice, however, need not be dependent on the fishmonger for specimens. In cellars, gardens, hedges and ditches, under flat stones, in dry moss, among moist dead leaves, in the loosened decaying bark of trees, crusta- ceans are to be met with almost everywhere. These are the so-called wood-lice, including those known by the trivial names of Pill-bugs and Slaters, Millepedes, and Carpenters. One species, small and white and slow in movement, is frequently to be found in ants' nests, and seemingly never elsewhere. All this set of animals, though air-breathing and living on land and often possess- ing great agility, belong to the Isopoda in common with the marine species above mentioned that leads its apathetic life within the carapace of the prawn. From almost every little brook and pond in England the amphipod, Gammarus pulex, and the isopod, Asellus aquaticus, may be fished without difficulty and without 14 A HISTORY OF RECENT CRUSTACEA any stint of numbers. Less commonly the innocent well- shrimps, which are also amphipod crustaceans, may be obtained from wells. It may be 'proper to mention that the well-shrimp is not poisonous, and that it nourishes in water which is perfectly wholesome. A different view of its character is probably entertained by many owners of wells, who are on that account unwilling to mention or acknowledge its presence. From stagnant ponds various species of Entomostraca may be obtained in vast abund- ance. Some of the Phyllopoda are found only in brine pools. The brine shrimp, Artemia, breeds in vast num- bers in the mud of the great Salt Lake of Utah. In South America one of the Ostracoda very singularly dwells on the leaves of a plant. The river crayfish and crusta- ceans parasitic on freshwater fish are pretty widely dis- tributed. Highest in known range of all the Crustacea are the Isopods and Amphipods taken by Mr. Whymper at a height of 13,300 feet on the Great Andes of the Equator. In many parts of the world there are land-crabs, but none of these live in the British Isles. This is referred to as follows in the ' Narrative of the Cruise of the Challenger.' In describing the visit to Ascension Island in the South Atlantic Ocean, the writer says : 'Land-crabs swarm all over this barren and parched volcanic islet. They go down to the sea in the breeding season ; they climb up to the top of Green Mountain, and the larger ones steal the young rabbits from their holes and devour them. It always seems strange to an English naturalist to see crabs walking about at their ease high up in the mountains, although the occurrence is common enough and not confined to the tropics. In Japan a crab is to be met with walking about on the mountain high roads far inland, at a height of several thousand feet, as much at home there as a beetle or a spider, and crabs of the same genus (Thelpliusa) live inland on the borders of streams in Greece and Italy.' France and Germany, as well as England, have reason to regret that the sunny south should have a monopoly of these land or river crabs, for they are delicate eating, and, SPECIMENS ON THE SHOKE 15 as writers of the sixteenth century inform us, they are much sought after for the tables of the Pope and cardinals. From what has been said it will be seen that those who live inland enjoy no inconsiderable opportunities of ob- serving crustaceans of various kinds, dead or living. The common and easily obtainable specimens will, as a rule, not be of the same species in different parts of the world, but they will often belong to the same or closely allied genera, and they will in any case afford ' similar facilities for study. The traveller would do well to remember that kinds easy to collect abroad or cheap to buy in foreign markets will probably be rare in his own country, and that therefore preserved specimens may be of future value to himself or acceptable to his friends at home. Passing, however, from inland resources to those of the sea coast, the student will find an enormously greater and an almost bewildering variety of forms to engage his at- tention. Shore-crabs and hermit-crabs are often obtru- sively conspicuous, as also are the operculate cirripedes with their sharp-edged shells coating large surfaces of rock. When a flat stone is lifted, not unfrequently a small specimen of the edible crab may be seen nestling in the mud. If the position is chosen in order to gratify the sense of smell, one would be inclined to adapt the words of the poet to the situation, and say that crabs want but little here below, but want that little strong. Cling- ing to the under- surface of a stone, a group of the broad- clawed Porcellana, the hairy porcelain crab, will often be found. They try to look as if they were not there, or they endeavour to slidder rapidly away. If one is seized by the claw, it will adhere as tenaciously as it can to the rock, and sometimes end the unequal contest by relin- quishing the claw and running off without it. The lobster- like Galathea, under similar circumstances, is ready either to fight or run, a very Achilles for courage and speed. Specimens of the masked crab and of various spider crabs, and of others not commonly found alive upon the shore, are often to be met with upon it when an obliging gale of wind has thrown their carcases landward. The common 16 A HISTORY OF RECENT CRUSTACEA shrimp will sometimes attract attention by making an abrupt spring, after which it sinks softly into the moist sand, from which its imitative colouring makes it barely distinguishable. The stretches of sand on the shore, which to unobservant or inexperienced eyes might seem quite barren and deserted, are often teeming with crusta- cean life. The upper and driest zone will be riddled with the burrows of the sand-hopper. Lower down several other species of amphipods lie at a very small depth beneath the surface. Little biting carnivorous isopods are there, and occasionally others that are vegetarians. In some localities Cumacea can be found, but never very far from the waves, nor, when they are present, must it be expected that these animals will make a striking feature in the landscape. They are remarkably unobtrusive. Where rocks and rock-pools and various kinds of seaweed abound, and especially on sheltered coasts, a very large number of species of amphipods and isopods may be obtained, these being in most instances distinct from those found in the sand. Here is to be seen Orchestia, the shore-hopper, a near ally of the sand-hopper, Talitrus. Here are two of the marine species of Gammarus, and examples of their cousins Melita and Mcera, all of which, when on land, slip or wriggle along on their sides, and have in consequence been irreverently spoken of as ' scuds.' Many other forms, including some of the Caprellida3 or skeleton-shrimps, can be obtained by examining tufts of the finely branched sea- weeds. At the lowest ebb of the spring tides, a day or two after new moon or full moon, species may be obtained which are rarely or never procurable higher up on the shore. Several of the isopods, however, may be taken, indepen- dently of the lowness of the tide, roaming among the coarser weeds, and mimicking in various ways the colours around them. The rocks which look least interesting, having no vegetation except the short black crumbling foliage of the Lickina pygmcect, supply the curious Cam- pecopea hirsuta, an isopod easily to be confounded with the leaves of the tiny plant which shelters it. Found among cirripedes at low tide, however, it displays much brighter VARIOUS LODGINGS 17 colouring. Where wooden piles have been driven into the shore within tide-marks, the part which the water reaches is almost sure to be very soon attacked and taken posses- sion of by two or three very distinct crustaceans, the two constant companions being the strange aniphipod Chelura terelrans, with a name signifying the boring claw-tail, and a perhaps equally mischievous isopod, known as Limnoria lignorum, or the Gribble. With these is frequently asso- ciated one of the cheliferous isopods, the species Tanais vittatus in England, and Tanais filwn in America, not con- cerned, it may be, in making the excavations, but only using them when made. Some Amphipoda and Isopoda shelter themselves in sponges and some in the branchial sacs of Ascidians. Many free-living Copepoda may be obtained in rock- pools and by washing seaweeds, others from various Asci- dians. Those parasitic Copepoda, which are commonly known as fish-lice, may often be procured by examining fishes when first brought to shore, and before they have been prepared for display on the fishmonger's board. New species of Crustacea have sometimes been discovered by the examination of the contents of a fish's stomach. This same repository will also occasionally yield good specimens of already known species. The Cirripedes are all marine, most of them impatient even of brackish water, although one species, Saldnus im2?rovlsus, Darwin, will live contentedly for some time in water that is quite fresh. Several species are obtainable between tide-marks. Many attach themselves to the sub- merged sides of ships, and to other floating objects. Some make their home in sponges, corals, or shells, and in con- sequence specimens not sought for their own sake are frequently distributed by the commerce of which their dwelling-places are the more direct object. For the Gigantostraca collectors in England must content themselves either with fossil or with imported species. In New England, the horseshoe crab, Limulus poly-pliemiis, may be had at or jusfc below low water. By availing himself, then, of those Crustacea which c 18 A HISTORY OF KECENT CKUSTACEA live on land or in shallow waters, or on the coast, and of those specimens which are brought to shore either as or in connection with articles of food, the student may obtain a thoroughly representative collection. Closely as all the easily accessible localities and resources have been already searched and examined, even from among them he will find it still possible to add new species to the long roll of those hitherto known. In many of the forms that are common and abundant, and that have long been familiar to science, he may, by diligent observation, find features of great interest that have heretofore escaped notice. One discovery he will almost certainly make, that the objects of his study do not deserve the epithets of contempt and disgust so freely lavished upon them by the ignorant. At every step he will be increasingly charmed by the striking characters which different species exhibit, by the delicate grace or the intricate mechanism of the separate parts, and by the marvellously varied adaptation of the different or- ganisms to their diverse modes of life. It is, however, in the waters of the ocean, from the surface down to the abyssal depths, that the vast majority of the Crustacea are to be found. Of the lower limits of the so-called bathymetrical distribution a good general idea may be formed from the results of the dredging and trawling carried on by the Challenger, during a voyage of nearly seventy thousand miles. Of the Brachyura indeed, only a single specimen of a single species was taken so low down as 1,875 fathoms. Mr. Miers, who named it Ethusa (Ethusina) challengeri, says : ' This is the greatest depth at which any Brachyurons crustacean was taken by the expedition, and also, I believe, the greatest hitherto recorded for any species of crab.' It was not, perhaps, to be expected that members of the highest order in the class would either need or condescend to penetrate into the very lowest regions, where light and heat and vegetation, not to speak of cheerful society, must at the best be very scanty and extremely scarce. The very genus Ethusa, with its sub-genus or neighbouring genus Ethn- sina, seems to apologise for frequenting levels beneath its SPECIMENS IN THE DEEP SEA 19 natural rank by including the forms which, as Mr. Miers observes, ' evince the greatest degree of degradation from the Brachyuran type.' It approaches in fact the group which till recently held a distinct position under the name of the Anomura. Of these Dr. Henderson observes that they occupy an intermediate position between the Macrura and the Brachyura, in regard to the limit of depth at which they are found, the more highly specialised forms being, like the Brachyura, found in shallow water and at moderate depths, whereas the more primitive macruran types extend to the abysses of the ocean. The single and singular specimen on which the species Tylaspis anomala, Henderson (see Plate VII.), was established, ' came from the greatest depth at which any anomurous crustacean was taken by the Challenger,' the depth in question being 2,375 fathoms. In the Macrura two genera, Bentliesicj/mus and Gennddas, instituted by the late Mr. Spence Bate, descend to 3,050 fathoms, and have nowhere been found dwelling with less than 300 fathoms of water above them. It is not perhaps surprising that most of the specimens were brought up ' in a soft, pulpy, and collapsed condi- tion,' for it is calculated that each perpendicular mile, that is, each 880 fathoms of water, exercises a pressure of a ton upon each square inch of an animal's surface. As long as the fluids within correspond with those outside the body, there is a state of comfort and efficiency, but when this equilibrium is suddenly destroyed, not only a crus- tacean but any other creature is likely to feel weak and discomposed. Of the Schizopoda Boreomysis obtusata, Sars, was taken from a depth of 2,740 fathoms. On the other hand the Stomatopoda are content with far less profound explora- tions. Mr. W. K. Brooks reports that ' they are usually found in very shallow water, and with the exception of the specimen of Squilla leplosquilla, taken in the trawl by the Challenger in the Celebes Seas from a depth of 115 fathoms, and a specimen of Lysiosquilla armata, which Mr. S. I. Smith found in the stomach of a Lopholatilus from 1 20 fathoms, they are all from very moderate depths.' The Challenger c 2 20 A HISTORY OF EECENT CRUSTACEA found a cumacean as low down as 2,050 fathoms, but some years earlier the Swedish Spitzbergen expedition obtained the appropriately named Diastylis stygia from the still lower deep of 2,600 fathoms. The Isopoda extend down to 2,740 fathoms, the Amphipoda possibly, but by no means cer- tainly, to 2,500. Among the Entomostracans, a Phyllo- carid species came from 2,550 fathoms, Ostracoda from 2,750, the strange copepod, Pontostratiotes abyssicula, Brady, from 2,200, and a parasitic copepod, Lerncea abys- sicola, was attached to a deep-sea fish brought by the trawl from 2,400 fathoms. Lastly, of the Cirripedes the great Scalpellum regium was dredged from a depth of 2,800 fathoms, the character of these animals giving more cer- tainty than can be had with free-swimming Crustacea, that the specimens actually came from the depth assigned. In the use of trawls and dredges with open mouths, there is always a chance that specimens may be captured in the course of lowering or hauling in the instrument, instead of while it is being dragged along the ocean floor. By this means the record of the occurrence of specimens at as- tonishing depths is left open to some question. Yet on the whole there is fair reason to believe that most of the principal groups of Crustacea have representatives capable of supporting existence in regions of dense gloom, with a temperature icily cold, and under a column of water from two to three miles in height. Many species, indeed, of the Crustacea show a preference for a frigid climate, since where this condition prevails their swarms are far vaster and their bodies more bulky and solid than in waters less cold. These Polar forms, therefore, find no inconvenience, but the reverse, in the unheated tempera- ture of the great depths, and though probably many of them could not possibly pass the tropical waters at or near the surface, far down there is a suitable water-way for them from one pole of the earth to the other. It is rather the task of national expeditions than of any private collector to procure the exceptional forms which the remotest abysses of the sea have yielded and may be expected still from time to time to yield. There METHODS OF CAPTUEE 21 are, however, unstinted riches of natural history which the ordinary student may obtain with comparatively simple means. By the use of the towing-net from a boat, espe- cially after sunset in warm and calm weather, numerous larval forms of Crustacea are to be obtained, as well as adult forms of various orders. By dredging in a few fathoms, or even in a few feet, of water, species enough to occupy weeks and months of study may often readily be secured. For this work sheltered bays and inlets are favourable. When the dredge brings up apparently nothing but rugged pebbles and the worn shells of departed molluscs, these are not to be despised. Among them may be found the little crabs of the genus Ebalia, at the first glance perhaps rejected as if pebbles themselves. Rare Tanaids may come creeping out of the crevices of an old oyster shell. When sea-weeds are brought up in the dredge, they are not to be cast aside after a hasty exami- nation as unproductive. They should be placed in a vessel of shallow water, and, though the crafty inhabitants lie close, they will eventually come forth. Sand and muddy ooze scraped from the bottom requires to be passed through a sieve or stirred about in a pailful of sea-water. After the stirring, and before the animals have time to regain the sand, the water must be poured off through a muslin bag which will retain the desired specimens. Some species, besides the edible ones, may be obtained by a sort of systematic fishing. A dead crab, for instance, let down in a lobster-pot, will attract one species or another accord- ing to the locality, the clan trooping to the feast in hun- dreds and thousands till they have consumed every par tide of the dainty repast. The voracity, indeed, of some among the smaller Crustacea is such, and their numbers in some places so enormous, that they have been known in a single night to clear all the flesh off a dead seal. To such appetites almost any carrion is a sufficiently alluring bait. There is little need for surprise, under the circumstances, at the label on certain museum specimens, intimating that they were ' pulled off the head of a bear let down to the bottom to be cleaned.' Some of the Amphipoda attack the 22 A HISTORY OF RECENT CRUSTACEA Lead and other parts of the whale while the monster is still alive. On the other hand, whales and seals, and fishes large and small, swallow down the Crustacea in a truly wholesale manner, and so prevent these prodigiously prolific animals from producing a complete block in the cooler parts of the ocean. Independently of this interest- ing exchange of courtesies, which consists in alternately eating and being eaten, there is another kind of associa- tion between crustaceans and other animals, known as commensalism. In this the one creature lives, not at the expense of the other, but merely in companionship with it. Thus, on the common starfish there is found a thread- like minute species of the Caprellidae. Though the star- fish is very frequently to be met with on the shores, its companion Par iambus ti/picus (Kroyer) l is only seen 011 dredged specimens, so that apparently this tiny animal has the sense to disengage itself when its host is being driven into an unsuitable or dangerous position. Some of the Amphipoda Hyperidea are very frequently to be found upon jelly-fishes. One of the Gammaridea, Iscea Montagui, Milne-Edwards, appears never to have been found except upon the Spiuous Spider Crab, Maia squinado. for clinging to which its feet, with their serrate widened extremities, are peculiarly adapted. A French zoologist, M. Edouard Chevreux, some five or six years ago, was searching this interesting crab for its already well-known commensal, when to his surprise, among the algte and hydrozoa, with which the carapace is usual!} 7 decked, he found not only the species he was in search of, but no less than twenty- two other species of Amphipoda into the bargain. Maia squinado is not found far to the northward. On the other hand a very distinct crab, but with some external re- semblance to it, Litkodes maia, is not found far to the southward. Such facts of distribution are often of scien- tific importance. For instance, with regard to the com- paratively narrow strip of land which separates North from South America, the geologist will desire to know how far the crustacean fauna of the sea on one side of the 1 Formerly Podalirius typicus. DISTRIBUTION 23 isthmus corresponds with, that 011 the other. A close- agreement would dispose him to consider that not so very long ago, in the large measurements of geological time, the Atlantic and Pacific may have been connected by a natural canal. From great divergence, such as is known to exist in the molluscan fauna, he would infer that the passage existed, if ever, only at a very remote period. In the large freshwater lakes of Southern Sweden, it was dis- covered some thirty years back, that a remarkable marine fauna existed, and the inference ingeniously drawn from a review of all the connected facts has been, that these sheets of water were at one time part of the sea, but have been cut off from it by the gradual elevation of the land. Upon this supposition, while the water was gradually losing its saltness, its marine inhabitants, with equal steps, were becoming habituated to a freshwater existence. But it must not be forgotten that the transfer of marine animals to brackish and fresh waters mav take place bv various modes / u of migration quite independently of geological changes. It has been noticed as curious, that shells, insects, and plants, inhabiting fresh water, are of comparatively few species, but those few very widely distributed. Mr. Belt ingeni- ously remarks that, in the oscillations of sea and land, the oceanic and continental domains, though shifting, are con- tinuous, whereas every freshwater area is liable to be again and again completely overwhelmed. By this means the freshwater species of narrow range may be entirely de- stroyed, and onlv families of wide distribution will survive. t/ J 4/ The application of this theory to the Crustacea is worthy of study, but the facts which it is designed to explain do not embrace the whole of the globe. The Isopod Asellus aquations and the Amphipod Gammarus pulex are obvious instances of freshwater species with an enormous range. Yet from the fresh waters of the Malay archipelago the Asellidaa and Gammaridee are said to be entirely wanting. On the other hand, Professor Max Weber has recently observed that, while Europe can show but seven species of freshwater decapods, the Indian archipelago can boast of more than eighty. 24 A HISTORY OF EECENT CRUSTACEA CHAPTER III MAGNITUDE Ix zoology, size attracts attention in comparison with two standards. Man contrasts the bulk of an animal either with the average in his own order or with that of the group to which the particular animal belongs. An elephant is a huge beast, not in competition with a whale, but with a human being. A hornet less than a man's little finger is a monster beside a house-fly or a gnat. As in all classes the majority of individuals conform pretty closely to the average magnitude, the mind becomes trained to regard the exceptional extremes with wonder, often not unmingled with admiration when the mass is not smaller but greater than common. Among the Crustacea there are forms, not indeed surpassing all others in diminutiveness, but at any rate so exceedingly small that the sharpest eyes could perhaps never have found out that they were crustaceans without the aid of the microscope. Here it is that the philosophical naturalist sometimes finds chief reason to marvel, in perceiving the whole machinery of life, enabling active locomotion, nutrition, and repro- duction, with senses, a power of choice, and the capacity for feeling pleasure and pain, all packed away as neatly and conveniently as possible in so extraordinarily small a casket. For preliminary studies creatures of more con- siderable compass hold an obvious advantage, and with most observers it is rather the giants of an order than the dwarfs that are deemed especially remarkable and worthy of the notice which they are fitted readily to engage. Some of the old writers probably understood OLD STORIES 25 that their readers would take more interest in a large crustacean than in a small one. For this reason, no doubt, Olaus Magnus declares that between the Orkneys and the Hebrides there lives a kind of lobster so large and strong that it can. catch a swimmer in its claws and squeeze him to death. His picture, as will be seen, repre- sents a bearded man as a mere plaything in the lobster's arms. The human race is avenged in the companion picture, where a lobster twelve feet long is itself being ruthlessly devoured by a ' rhinoceros whale.' Though these myths are many centuries old, they still have an amusing interest to the Anglo-Saxon from having been localised in British waters. It is, however, very extraordinary that at the beginning of the present century a travelled French naturalist of eminence should have accepted a statement little differing from that of Olaus. L. A. G. Bosc in 1802 published his ' Natural History of the Crustacea, contain- ing a Description of them and their Manners,' in the In- troduction to which he says : ' It is related that on the coasts of the isles of America, where the crabs are in great profusion, they engage during the pairing season in desperate conflicts, which often result in the death of numerous individuals, and always in the loss of a great many of their limbs. It does not appear that the Crustacea of Europe ha\re this custom ; but their small numbers, and the perpetual hunting after them, do not permit so easy an observation of their habits, as in warm countries, where it is said that they are of a size so monstrous, that they attack men, and have eaten several, amongst others the famous sea captain Francis Drake (Francois Drack), who, although armed, could not avoid this fate.' ! This passage is still retained in the revision of 1830, edited by the well-informed Desmarest. The story ap- pears to have been derived from De Paw's ' Recherches Philosophiques sur les Americains ' (t. i. p. 245), a work which describes the death of Drake as follows : 1 Histoire Naturelle des Crustaces, conte.nant lew Description et leitrs Mceurs, p. 149. 26 A HISTORY OF EECENT CRUSTACEA ' This navigator having landed on the Isle of Crabs in America, he was there immediately surrounded by these animals ; although he was armed, although he made a stout resistance, he had to succumb. These monstrous crustaceans, the largest known in the world, cut in pieces with their claws his legs, his arms, and his head, and gnawed his carcase to the very bones.' l There are some elements of truth in this blood-curdling story. It is true that Drake died in the West Indies. It is true that he landed on Crab Island. It is true that he met with huge crabs. But he died on board his own ship of a sickness brought on by disappointment, and his body wrapped in a leaden shroud was buried in the sea. The Crab Island on which he once landed was in the Eastern not the Western Main, nor did he lose his life upon it. The land- ing was in the course of his successful voyage round the world, and it was not the crabs that ate Drake, but Drake and his people that ate the crabs, of which a single one, they afterwards said, was sufficient to make a meal for four men. That might well be, if the crabs at all resembled the giant crab of Australia, Pseudocarcinus gigas (Lamarck), 2 in which the carapace is said to be sometimes two feet in breadth, and in which one of the claws of the front pah- attains a vast bulk. Such crabs as these may be thought to justify a statement in Linschotten's ' Voyage to Goa,' according to which, ' To the South of Goa, at a place called St. Peter s Sand, there are Crabs so great and numerous, that Men are forced to keep a good Watch to defend themselves, for if they get one in their Claws it costs him his life.' No crustaceans, however, either extinct or extant, can 'Compete in size and power with those fabled by Olaus and De Paw. In the far distant Silurian age the fossil genus Pterygotus among the Merostoniata is supposed to afford the largest specimens of the whole crustacean class. 1 Nourelle Biograplue generale, edited by Hoefer, 1. 14, p. 737. 1855. - An author's name appended in parentheses by custom signifies that he is responsible only for the species, and that this no longer stands in the genus to which he had assigned it. A WIDE STRETCH 27 The remains make it probable that some of them attained a length of six feet and a breadth at the widest part of the body of nearly two feet. The sculpture on the carapace, like conventional feathers drawn by some old Assyrian artist, is thought to have led the Scotch quarrymen to call these giant fossils by the quaint name of Seraphim. 1 Great as their size was, their organisation would have little fitted them to cope with an armed knight. Their nearest living allies belong to the genus Limulus, in which the eastern King Crab, Limulus moluccanus, attains a breadth of a foot by a length of two feet, although, to be sure, nearly one half of the length consists only of a great caudal spine. Among the Brachyura, Japan possesses a species which is certainly from one point of view a rival in size to the largest Pterygotus, and may almost seem to justify the old mythical narratives, for Macrocheira Kampferi, de Haan, as a specimen in the British Museum shows, can span eight feet, and it is said that sometimes even eleven feet are within the compass of the outstretched arms of the male. But portentous as we must allow these dimen- sions to be, the animal is after all only a spider crab, with comparatively weak and spindly legs, and a carapace which seldom if ever exceeds twelve inches in either length or breadth. The fossil Trilobites, which compose the third order of the Gigantostraca, include indeed many species of incon- siderable size, but they are also represented by forms such as Asaphus tyrannus, Murchison, about a foot long, and others in the genus Paradoxides, measuring twenty-one inches. Among the spiny lobsters or crawfish, a New Zealand species, Palinurus tumidus, has recently been described by Mr. T. W. Kirk as measuring twenty-four inches from the tip of the beak to the end of the tail, and as having the carapace very much swollen, and measuring 21^ inches in circumference. The European Palinurus vulgaris attains a length of 18 inches, also without including the antenna?, 1 H. Woodward, Transactions of the Palceontoqranliical Society, 1866, p. 42. 28 A HISTOKY OF RECENT CEUSTACEA which are sometimes considerably longer than the animal's body. The common lobster, though less bulky in the trunk and with more slender antennas, attains an equal length, or by inclusion of its long and powerful claws might claim in this respect far to exceed the weak-limbed Palinurus. There is an Australian crayfish, Astacopsis serratus (Shaw), from ten to twenty inches long, and weighing some pounds, which makes a fine show when compared with the much more modest dimensions of the English crayfish. In the same way Leander serratus (Pen- nant), the common prawn of British markets, is humbled by contrast with Palcemon carcimts, the river prawn of the West Indies and Guatemala, of Surinam and the Ganges, with its lobster-like size of twelve inches long. Palce'inou Zr, from the Pacific Islands and India, exaggerates one of the characteristics of the genus to which it belongs, inas- much as a male specimen five inches in length will have the second pair of legs nearly eight inches long much longer, therefore, than the body which carries them. The Her- mit Crabs appear to attain their maximum at about eight inches, a length not inconsiderable, seeing that it has to be accommodated to the vacant shell of a univalve mollusc. One, however, of their near kindred, Liihodes camschatica (Tilesius), has sometimes a span of four feet. This makes its hermitage not in the shell of a mollusc, but in some cranny of the rocks. From this fastness it takes vengeance on the crab-eating octopus, and is itself so firmly lodged that it cannot easily be dragged out, except in fragments. Of shrimps, Pasipficea princeps (S. I. Smith), dredged by the Albatross in 1883, may be accepted as the leader, seeing that it is not only far larger than any of its own genus hitherto known, but by its length of more than eight inches and a half, it exceeds all examples of kindred geneia. Among the Schizopoda the more familiar species are quite the reverse of bulky. A specimen of Gnathophausia ing ens (Dohrn), measuring from the tip of the rostrum to the extremity of the telson or tail 157 millimetres, or 6 inches, is spoken of as possessing 'a truly gigantic size A ROYAL GIFT 29 for a Schizopod.' It is also said that ' this form ranks, therefore, as the largest by far of all hitherto known Schizopods,' although in truth an allied species in the same genus, Gnatkophausia gigas, v. Willemoes Suhm, obtained by the CJiallenger from a depth of 2,200 fathoms, measures 142 mm., or of inches. Both of these species, with one or two others in the same genus, such as Ghiatlwplmusia Goliath, A. Milne-Edwards, far surpass most of those in the sub-order, the length usually ranging from half an inch to two inches. Of the Stomatopoda, some are no more than three- quarters of an inch in length, but of the species Lysio- sguilla maculata (Fabricius), a male specimen, presented to the naturalists of the Challenger by the King of Amboina, fell short only by three-sixteenths of an inch of measuring a whole foot. The Cumacea are a feeble folk. In some species the slender frame, with trunk and tail and tail appendages all told, does not exceed, or even equal, a twelfth of an inch. Only the arctic Diastylis Goodsiri (Bell), occasionally yields a Goliath of an inch and two-fifths. In the Isopoda there is a far greater range of size. Within a single genus, Eurycope mutica, Sars, which measures about one milli- metre and a third, is contrasted with Eurycope gigantea, Sars, which reaches 33 millimetres, or about an inch and a third. Anilocra gigantea (Herklots), measuring three inches and a third, would seem a veritable monster in this sub-order, were it not far surpassed by the ex- tremely exceptional Bafhynomus giganteus of Alphonse Milne-Edwards, which is nine inches long by four inches broad. 1 This prize was fished up by the United States Survey steamer Blake, under the supervision of Alex. Agassiz, from a depth of 955 fathoms, in the region of the Gulf Stream, to the north-east of the bank of Yucatan to the north of the Tortugas. Among the Amphipoda, none yet discovered reach more than about half the dimen- sions of this great Isopod. At the other end of the scale 1 11 mesure, en effet, pres de O m , 23 de long sur O m 10 de large. 30 A HISTORY OF RECENT CRUSTACEA there are Gamraarids, Hyperids, and Caprellids, of micro- scopic proportions, but for colossal species each Amphipod division must be content to compare its members one with another, rather than with the outside world. In the threadlike Caprellidea, some of which might be regarded as creatures of only one dimension, the Challenger species, Dodecas elongata, by help of its antennae and hind legs, can stretch over a space of three inches. In the Hyperidea, liJtaldosoma armattim 1 is not quite so thin, but its length is greater, since the tip of its rostrum is sometimes nearly five inches distant from the extremhVy of its caudal appen- dages. In the same section the remarkable genus Cystisoma has species which combine a length of four or five inches with the respectable breadth and depth of an inch in the amplest part of the head. The chief boast of the Gam- maridea is Eurytlienes gryllus (Lichtenstein in Mandt). The first specimen observed of this full-bodied animal was three inches long and two inches and a quarter round the waist. It was disgorged in the far north by a wounded arctic petrel. Twenty-seven years later it again attracted scientific attention, singularly enough the specimen this time coming from the far south, for it was taken from the stomach of a fish caught off Cape Horn. Its body was nine centimetres long and three deep in other words, more than three and a half inches in length and more than one inch in depth. In recent years the apparent anomaly of its occurrence both in arctic and sub-antarctic waters has been explained by evidence that it can make itself at home in the intervening expanse, since in 1883 the American steamer Albatross captured a specimen over four and a half inches long, in deep water off the middle Atlantic coast of the United States. This must be regarded as the bulkiest of the Amphipoda yet known. The Entoniostracans make their position in the world's 1 It is doubtful whether the change of this name to Xiphocepkalus armatus, as proposed by Dr. Bovallius, can be justified, since the name Xyphicephale was only given by Eydoux and Souleyet on Guerin's authority in trivial not in scientific form, an ill-spelt French name for a genus rather hinted at than established or defined, the name more- over not being definitely given but only contingently suggested. A DIMINUTIVE GIANT economy remarkable far more by their incalculable num- bers than by their individual measurements. In regard to the Phyllocarida, Dr. Packard remarks that the paleo- zoic species were gigantic in size, some being about a foot or more in length, while our recent Nebalia is less than an inch. The new species, Nebaliopsis typica, Sars, however, may extend the magnitude of modern examples to an inch and three-fifths. The Phyllopoda can exhibit Esilieria, calif ornica, Packard, in a shell 16 millimetres long, ten broad, and four thick, and Apus Newberryi, Packard, with the carapace, the abdomen behind the carapace, and the slender caudal appendages, each an inch long. But the amplitude more usual in the sub-class may be estimated by the respect paid to such a species as Bythotrephes crassicaiida, Lilljeborg, 5 mm. long, one of the Cladocera. This is a colossal species of a fifth of an inch ! Among the Ostracoda, Grossophorus imp&rator, G. S. Brady, is one third of an inch long, and with good reason Dr. Brady cannot restrain his admiration of ' this noble species, cer- tainly the largest of the known Cypridinidas.' In the Thyrostraca or Cirripedia a total length of two or three inches will deserve and earn the lordly epithets of eximium, regium, and gigas, but the Patagonian Balanus psittacus (Molina), which grows rapidly and is ' universally esteemed as a delicious article of food,' attains six inches in length by three and a half in diameter, and a specimen has been found no less than nine inches in length, though only two and a half in diameter. Of the pedunculate species, Lepas anatifera, the common Goose Barnacle, can grow a stalk more than a foot long. Darwin says : ' The largest specimen which I have seen had a capitulum two inches in length ; the longest, including the peduncle, was sixteen inches.' 32 A HISTOEY OF EECENT CKUSTACEA CHAPTER IV ON STRUCTURE THE body of a crustacean is externally divided into a theo- retically constant number of segments and paired append- ages. In the Malacostraca, it generally exhibits a more or less clear partition into head, trunk, and tail, or, as these parts are sometimes called, cephalon, thorax, and abdomen. There is indeed a rather bewildering supply of alternative names, which it is needless for the moment to discuss. The objections to the use of the word thorax have been already mentioned. Throughout the sub-class, however, the head is found to be united to some portion of the trunk, and to denote this variable combination the convenient word ceplicdo-tlwrax is very frequently employed for the region covered by the carapace. It is a matter of opinion whether the full number of true segments should be reckoned as twenty or twenty-one, since that which is called the telson, and which is regarded by many authors as the terminal segment, is considered by others not to be a true twenty-first segment, but a median outgrowth of the twentieth. Scarcely ever can the whole number be dis- tinguished in one and the same animal. As the Entomos- traca always have more or fewer than the theoretical num- ber, there is some need for the eye of faith to include them in the reckoning. The foundation of the integument which forms the external skeleton of a crustacean is a tolerably flexible substance called chitin. This is hardened and consolidated by being impregnated with calcareous salts, and the absence of these leaves the skin the requisite flexibility for acting as a joint between one hardened part WHAT IS A HEAD ? 33 and another. But the joints themselves are sometimes -consolidated, and then it is said that two or more segments have coalesced. This is not a merely arbitrary statement, for, comparing the Malacostraca one with another, the conclusion cannot be avoided that a single segment is limited to a single pair of appendages. Segments which are not independent in one of the families will be found well articulated in another, and those which can least l>oast of freedom nevertheless frequently point to an origi- nal independence by some suture or groove, if not by the actual separateness of the segments! ring in some small part of its circuit. No rigid definition is possible of a bead. It is bound to contain the animal's mouth, and may be expected to include the brain and organs of the senses of sight and hearing, smell and taste. In birds and in mammals its limits are conveniently denned by the neck, but in the Crustacea there is no such obvious constriction separating it from the trunk. Consequently its true limits here are still a subject of dispute, which cannot be settled offhand by an appeal to the cervical groove, even when that is con- spicuous. By various authorities the first five, six, or seven segments have been assigned to the head, and in the higher Crustacea it might not unreasonably be regarded as comprehending the first nine. This will be understood from a consideration of the form and functions assumed by the several appendages, only those in front of the mouth- opening or directly contiguous to it being accepted without dispute as cephalic, although others in variable number are concerned in the operation of feeding. Glancing along the whole line of limbs, as the out- growths from the segments have some right to be called, twenty pairs in number, we find them successively devoted to seeing, feeling and otherwise perceiving, feeding and presumably tasting, grasping and striking, walking and digging, swimming and leaping. But although the order in which they act may thus be generally stated, there is not unfrequently a transfer of function from one part of the line to another. The feelers may be employed to assist D 34 A HISTORY OF RECENT CRUSTACEA in swimming or climbing or clasping. The rnouth-organs of one group are the grasping weapons of another. The walking legs of one set are elsewhere adapted for swim- ming. There are also other functions conjugal or maternal in which the swimming legs or the walking legs may take part, while the breathing apparatus, simple or complicated, may be connected with the mouth-organs or limbs of the trunk or both, or else with the swimming organs of the tail-part, commonly called the pleon. These and other curious modifications are largely made use of in classifying the Crustacea, and to understand the unavoidable intrica- cies of any system of arrangement, the outgrowth of each segment should be studied, in some form the less abnormal the better. 1. The first segment is known as the ocular or ophth- almic. This is clearly articulated in the Squillidas, but only occasionally in other groups, as in the macruran Plesi- oniJia uniproducta, Sp. Bate. Its individuality is in no way indicated in the sessile-eyed Crustacea, in some of which the eyes pretty well cover the whole dorsal surface of the head. In the Brachyura and Macrura its original independence can often be traced, but it is in these chiefly attested by the pair of movable appendages which it almost invariably carries. Now, just as it is thought that all the segments represent a common original type variously modified, a similar view is applied to all the appendages that arise from the segments. The resemblance, in fact, is often very obvious between the antennas and the swimming feet ; between the laminar maxillaa near the mouth and the opercular and breathing plates in the tail ; between the maxillipeds, which are in- struments of nutrition, and the ambulatory legs of the trunk ; so that a connection, at first sight very improbable, is satisfactorily established between them all, when the comparison has been sufficiently extended. Yet it de- mands some exercise of faith on the part of a novice to accept the declaration that this homology holds between the claw of a lobster and its eye. No two parts of an animal could well be more unlike in appearance and func- OPTICAL INSTRUMENTS 35 tion. It is unusual to tliink of a creature's eye as one of its limbs, for only by a figure of speech do we describe a person as grasping the whole situation at a glance. Never- theless, there are very few inclined to dispute that the eyes of the Podophthalina have really been developed upon appendages by nature equivalent to the rest of the series. Any one acquainted only with the extremely short-stalked eyes of some of the crabs might be excused for thinking this view extravagant, but its improbability is lessened when we observe the long-stalked eyes of the Angular Crab, Qonoplax rhomboides (Linn.), or those of the macruran Leucifer Rei/naudii, Milne-Edwards, or those, again, of Eretmocaris longicaulis (see Plate XIII.), a shrimp in which the eye is projected on a support actually longer than the animal. Moreover, the ocular appendage, besides being articulated to the head, is itself composed of two or three articulations. In the fast-running Ocypode cursor (Linn.), the peduncle is extended beyond the cornea of the eye, and terminates like an antenna in a pencil of long hairs. There is one instance on record in which the eye of a kind of lobster, Panulirus penicillatus (Olivier), has been observed to develop a jointed antenna-like lash, while the com- panion eye remained normal. This evidence is parallel to that on which a botanist infers that the petals of a flower are by origin modified leaves when he sees them occasionally assuming the form of the unmodified leaf. 2. The second segment carries the first pair of an- tennas, sometimes called the inner or upper, or, without epithet, the antennules. In the Malacostraca normally these appendages consist each of a three-jointed peduncle and two flagella or lashes, composed of many joints or few, the inner or secondary flagellum being not unfre- quently absent altogether or rudimentary. In some in- stances, and in the Amphipoda Caprellidea and in the Entomostracan Copepoda not as an exception but as the rule, the first antennae are larger than the second, from which it results that the diminutive name antennules is rather convenient than appropriate. The superior size, however, is no indication of higher rank, but rather the D 2 36 A HISTORY OF RECENT CRUSTACEA reverse. These organs are sometimes most dwindled in families which can claim a decided precedence over others in which these appendages are well developed. Thus they are short in the crabs, but long in the lobsters and shrimps, and short in the normal Isopods, but long or large as a rule in the Amphipoda, and within the Amphipoda they are short in the Orchestida3, a family that claims superiority by its tendency to terrestrial habits. Those who have made themselves acquainted with Professor Huxley's volume, ' The Crayfish,' in the Inter- national Scientific Series, will be aware that in describing a crustacean appendage he names the first two joints the protopodite, which bears at its extremity on the inner side the endopodite, and on the outer side the exopodite. For these terms the shortened forms exopod and endopod will here be preferred exopod for exopodite, endopod for endopodite and protopodite combined and peduncle will be used for a variable number of basal joints. In the first antennas the peduncle consists, as already stated, of three joints, and by this circumstance the rule which widely prevails elsewhere that the so-called protopodite ends with the second joint of an appendage is broken without any obvious cause. Moreover, that which by its function and in general by its superior size appears to be the main branch is here the outer one, and not as usual the inner. It is conceivable that the exopod is wanting, that the main branch or principal flagellum is the true endopod, and that the secondary flagellum is an independent outgrowth. For the reasons mentioned, and some others, Dr. J. E. V. Boas considers that the first antennge are not homologous with the following limbs, but that both they and the stalked eyes ought to be regarded as limb-like sense organs. That besides being organs of touch, they are frequently organs of other senses, seems to be beyond doubt. In the Macrura at large the first joint contains an auditory apparatus. Sometimes the cavity is provided with a well-formed otolith or ear-stone. In the lobster and crayfish, Mr. Spence Bate says, ' the perforation is long, narrow, and slit-like, the aperture being scarcely AN ACOUSTIC TAIL 37 appreciable, and opens into a calcined chamber, more or less filled with particles of sand, which are voluntarily placed in position by the animal soon after casting its exuvium.' But while the higher Podophthalma have the organ of hearing thus placed, there are some the Mysidse which, extraordinary to relate, carry it in the tail (see Plate XIII.). In some of the Amphipoda otoliths have been detected in connection with the brain, not in, but behind the antennae. In general, the antennas are fur- nished with delicate plumose hairs, the vibrations of which assist in the conveyance of sound to the auditory nerves. Similar hairs in the Mysidse are connected with the caudal otoliths. The principal flagellum of the upper antennas is frequently furnished with a number of smooth setae or filaments, which were at one time described as auditory 7 cilia, though there was nothing to support this guess at their function, and though the term cilium was inappro- priate to the shape of these rod-like membranous filaments. It was noticed by various naturalists of eminence that the setae of this form were much more abundant in the adult males than in the young males or in the females. Ley dig supposed them to be not auditory but olfactory organs, and Fritz Muller independently came to the same conclu- sion, adducing in support of it their stronger development in the males, as in other cases male animals are guided by the scent in pursuit of the females. It can scarcely be said that their olfactory function is as yet absolutely proved, but they are evidently not well placed to serve the sense of taste, and for the senses of sight, hearing, and touch, there are other organs much better adapted, so that these glassy filaments, to be sensory organs at all, are in a manner forced back upon the sense of smell. The secondary or inner flagellum, according to Dr. Boas, is wanting in all genuine Nanplii that is, in the earliest larval stage of the crustacean. Its after develop- ment conforms to no known rule, since in some species it is not found at all, in others it is only rudimentary, whereas, on the other hand, among the Macrura it is not unfrequently much longer than the outer flagellum. Mr. 38 A HISTORY OF RECENT CRUSTACEA Spence Bate suggetts that its function may consist in pro- tecting and keeping clean the mass of cilia and filaments attached to the outer branch. In some genera of the Macrura, for example Palcemon and Alpheus, the principal flagellum divides at some distance from its base into two branches. In the Squillida3, also, there are three flagella. 3. The third segment carries the outer, under, or second antennas, sometimes called simply the antennas in distinc- tion from ' antennules.' They are rarely absent, as in the females of some Amphipoda. More often they are strongly developed, in some instances exceeding in length all the rest of the animal which carries them, the joints of 'the flagellum or lash being then very numerous. In the Malacostraca the peduncular portion embraces the first five joints. The exopod, when developed, as it gene- rally is in the Macrura, very commonly has the form of a thin plate known as the antemial scale, in Latin squama, while those who love long words are privileged to call it the scaphocerite. When laterally extended this broad scale must assist in keeping the animal upright in the water, a position which would otherwise with difficulty be maintained by long-bodied forms. In some Crustacea, the scale, though present, has not a laminar character, and it is then spoken of as the acicle. The first, or basal joint of the peduncle, is not unfrequently soldered to the wall of the head, and very often carries a tubercle in con- nection with the ' green gland,' of which the function is supposed to be renal, though it has not been with certainty determined. That this tubercle is of some importance may be inferred from the fact that in some cases where the antenna itself is obsolete the tubercle persists. It is not a little singular that up to thirty years ago or later, many naturalists of eminence regarded this tuber- cle as connected with the auditory apparatus, which they assigned to the base not of the first but of the second an tenure. Milne-Edwards in 1834 refers to the researches of M. Savart, who had discovered that the stretching of a fine elastic membrane over an opening was one of the circumstances best adapted to promote the appreciation of THE MANDIBLES 39 sound. Just such a membrane Milne-Edwards considers to exist at the base of the antennae now under discussion, and in some of the Brachyura he and his colleague Audouiii had investigated an inner apparatus capable of increasing the tension of the disk at the will of the animal, an arrangement which he compares with that of the auditory ossicles and the tympanic membrane of the human ear. It is only with reluctance that this description of a natural telephone can be relinquished. In some species, such as the common rock lobster, Palinurus vulgaris, there is a soridulating apparatus in the basal joints of the second antennae, and it is obviously unlikely that a sound-pro- ducing organ should have been developed in an animal's ear. 4. The fourth or rnandibular segment is of great im- pDrtance, since from this, or from it in conjunction with the preceding segment, the carapace is developed. Its appendages also, the mandibles, yield in value to very few of the other organs. In form they vary extremely, but are for the most part of powerful structure. Their edges meet over the mouth-opening between the upper lip and the lower. The trunk of the mandible is frequently massive, with a projecting, finely denticulate, grinding surface called the molar tubercle, and a thick or thin dentate cutting edge, often having also a variety of spines between these two processes. It is not seldom surmounted by a narrow piece, commonly called its palp, which never in the Malacostraca consists of more than three joints. Very rarely, and only among the Entomostraca, one of the joints of the palp has an outgrowth supposed to represent the exopod. Since theoretically the exopod always arises from the second joint of an appendage, it is argued that the trunk of the mandible must represent the first joint. But to this it may be answered that the exceptional out- growth just mentioned is perhaps not an exopod, and that at any rate in the first antennee there is a similar out- growth from the third joint. In Euchceta glacialis, Hansen, and some other Entomostraca, the mandibular palp divides into two branches from its second joint. Seeing that the first joint of a crustacean appendage is very rarely of large 40 A HISTORY OF RECENT CEUSTACEA size, it is a question whether the trunk of the mandible may not represent a coalescence of the first and second joints, or even of the first three or four joints. The latter supposition would explain the circumstance above noticed that its ' palp ' or terminal portion in the Malacostraca never exceeds the number of three joints, though it may be reduced to two or one, or may vanish altogether (see Plates XII., XV., XIX.). On the inner side of the man- dible there is sometimes, adjoining the cutting edge, a plate which more or less closely imitates that edge in its character. It has now been made probable that this secondary plate is a modification of one of the spines above noticed, and, as if to show the plasticity of nature, some- times the series of spines mimic the secondary plate. The upper and lower lip seem best to be regarded as modifications of the integument, where it is turned in to form the alimentary canal, commencing with the oesopha- gus or gullet. An American lady, Miss J. M. Arms, however, in her very clever little work on Crustacea, in Alpheus Hyatt's ' Guides for Science-teaching,' maintains that the leaves of the lower lip ' are independent outgrowths or buds from the integument, as much as any other pair of appendages; and the fact that the parts of the segment to which they must have belonged have disappeared, or cannot be readily found, is,' in her opinion, ' an argument of doubtful weight.' The theory that all the appendages of a crustacean are either legs or modified legs will strike a casual observer as rather strained in its application to the mandibles. That a crab should adapt the basal joints of a pair of limbs for masticating its food may seem as unlikely and absurd as that a man should have teeth on his elbows, and should draw them up in front of his lips for the purpose of biting and chewing whatever he wished to put into his mouth. To prevent all cavilling, however, on this point of the theory, the King Crab, Limulus, is so obliging as to ignore the ordinary mouth organs, and to use the bases of its actual walking legs as mandibles. THE MAXILLARY FAN 41 5. Close up to the lower lip, and as little leg-like as any of the appendages, are placed the first maxillas. They are almost always thin and foliaceous, with few joints, and those few not easy to distinguish. The pattern is ex- tremely variable. The functions are obscure. There are sometimes strong fringing spines which may assist in dividing the food. There are plumose hairs, some of which may be connected with the sense of taste. The position of these organs has also suggested that they may 'be useful in preventing the escape of food from the lateral angles of the mouth.' It is with these that some authors close the number of true cephalic appendages. Of those which follow some are frequently, bat none with the same constancy, developed into mouth-organs. 6. The second maxillae, when present, have generally the same thin flattened character as the first, but their structure is often more complicated. Among other pecu- liarities they have in some of the higher groups a mem- branous expansion or large lamina on the outer side, frequently termed the flabellum or fan, and compared by Milne-Edwards to a ventilating register (see Plate XI.). This species of valve is in constant and rapid vibration, in most cases forcing the water which has aerated the gills to pass out in front, so that a new supply may be introduced from behind ; but in some crabs (as Dorippe, Ranina, Leu- cosia) according to de Haan the water is introduced in front, and passes out behind. Huxley supposes that this valve may represent the epipod, that is to say, the branch which is given off by the first joint of an appendage, or else that it may be a combination of the epipod of the first joint with the exopod of the second. 1 Professor Sars re- gards it as the exopod, 2 while Dr. Hansen considers that it springs from the third joint. 3 In those Crustacea which have the branchias either not enclosed in a chamber or in one remote from the head, this part of the maxilla is either absent or rudimentary (see Plates XVI., XIX.). 1 The Crayfish, p. 170. (The scaphognathite.) : The Norwegian North Atlantic Expedition Crustacea, p. 21. 3 Orcrsigt over de paa Dijmpltna-Togtet indsamlede Krebsdyr, p. 193 note, and p. 252. 42 A HISTORY OF RECENT CRUSTACEA 7. The appendages of the seventh segment are dis- tinguished from the two preceding pairs by the name maxillipeds, meaning maxillary feet or jaw-feet, because they often conspicuously combine the function of a mouth- organ with the general appearance of a crustacean leg. This is very much the case in the Aniphipoda, where they conclude the series of cephalic appendages, having here something of the opercular function which they exercise still more conspicuously in the Isopoda. In the Copepoda, which are content with one pair of maxillae, there are two pairs of ' foot-jaws,' in regard to which the singular dis- covery has been made that they belong to a single segment, and yet do not violate the rule that a single segment is limited to a single pair of appendages. By tracing the process of development Dr. Glaus made it clear that they were in fact the exopods and endopods of a single pair of limbs, which had separated so as to wear the appearance of two distinct pairs, which is much as if the radius and ulna in the human arm were to become independent and produce a four-handed man. In the higher Crustacea these appendages, without being divided, are only the first of a series of three pairs of maxillipeds. Their forms vary exceedingly in the different groups. Sometimes the endopod is seven-jointed like an ordinary limb, at others the terminal part is reduced to insignificance. Often the epipod and exopod are important both in size and function. 8. In regard to the eighth segment, a difficulty arises as to how the appendages should best be designated. In some groups, such as the Amphipoda and Isopoda, they belong not only in theory but in fact to the trunk, and they have in these groups been called gnathopods, a word which, like maxillipeds, means jaw feet, and which was chosen to indicate that they grasped the food in a jaw-like manner. But in the higher Crustacea these appendages practically belong to the mouth and not to the trunk, their general appearance and functions allying them closely to the preceding pair. Under these circumstances it seems best to call them the second maxillipeds. For, A CENSUS OF LEG-JOINTS 43 though it has been strongly urged that one and the same term ought to be applied to homologous parts throughout the whole crustacean class, either nature has opposed the rigid application of such a system, or the wit of man has not yet been able to devise appropriate terms. It may here be mentioned that the full number of joints for a malacostracan trunk-leg is seven. With a view to uniformity of nomenclature, the afflicted naturalist has for many years had to deal with these seven under the following names : Coxa, basis, ischiuni, inerus, carpus, propodus, dactylus, which respectively signify hip, foot, socket of thigh joint, thigh joint, wrist, forefoot, and finger or toe. Originally the names were longer, all being podites, from coxopodite to dactylopodite, to the use of which the philosophic French still adhere, though the time-saving Anglo-Saxon has for the most part rejected them. Among other difficulties in this terminology under either form, it has to be remembered that the basis is the second, not the basal joint of the limb. The more reason- able plan is now being widely followed of naming these joints simply according to their numerical order, the coxa being called the first joint, and the dactylus the seventh. But the older names have still to be borne in mind by those who study the older literature. Even the numbers are attended by a very unfortunate element of confusion. The late Axel Boeck, when introducing the use of num- bered joints, was studying the Arnphipoda, in which the first joint of a leg is seldom, if ever, free. Taking into account, therefore, only the six free joints, he called the second joint the first, and made the finger the sixth, instead of seventh. In treating separately of the Amphipoda or Isopoda, many naturalists have followed Boeck's usage as reasonable and convenient. But when other Crustacea are considered in which an appendage has the first joint or perhaps all the seven joints free, they must be numbered from one to seven, and whenever a comparison is needed between the limbs of the Edriophthalrua and those in other groups, two different systems of numbering the joints cannot fail to be highly embarrassing. It must 44 A HISTOEY OF EECENT CEUSTACEA further be noticed that there are Crustacea in which one or other of the joints, most often the fifth, is itself multi- articulate, thus adding to the normal number, which oil the other hand is still more frequently diminished by coalescence, absorption, or complete failure of develop- ment, affecting various parts of the limb. 9. The ninth segment carries a very important and, at the same time, very variable pair of appendages, which, as the third maxillipeds, have in the higher Crustacea the same kind of opercular character that has been noticed as pertaining to the appendages of the seventh segment in some of the lower groups of the Malacostraca. In his celebrated and valuable work on the Crustacea of Japan, de Haan made great use of these third maxillipeds for classifying the Malacostracan group in respect to families and genera. The various joints of the eudopod by their shapes, relative size, number, and mode of articulation one with another, have yielded a multitude of characters. In the Amphipoda, where the appendages of the ninth segment are not mouth-organs, but constitute the second gnathopods, they are commonly the most powerful limbs of the trunk, being, no doubt in general, the animal's most efficient weapons for holding its prey. In the Isopoda, on the other hand, they are to be called gnathopods only by courtesy, being in general little distinguishable from the following pair of limbs. 10, 11, 12, 13, 14. The appendages of the five follow- ing segments have been and may sometimes conveniently be called perasopods, which means walking-feet. Among the Amphipods and Isopods they are usually adapted for walking, and in those groups the trunk, to which they are attached, is often called the perason, intended to signify the ambulatory part. Among the crabs and lobsters, and various other crustaceans, however, the first of these pairs is by no means adapted for walking, but ends in large claws or nippers, on account of which they are known as the chelipeds, and Mr. J. E. Ives proposes to call the four following pairs cruripeds, which means leg-feet, while Dr. A. S. Packard, unaware of what was intended by APPENDAGES OF TRUNK AND TAIL 45 perseon, has proposed to substitute for it ' btenosome,' a word of precisely the same sense. The epithets chelate and sub-chelate are of constant occurrence in descriptions of Crustacea. A limb is chelate when it has joints that will act together like a pair of tongs. Generally this character is produced by the hingeing of the seventh joint a considerable way down on the side of the sixth. When the seventh joint or finger can be folded back upon the sixth, although the latter is not produced into any thumb- like process to oppose it, the limb is then said to be sub- chelate, the claw being in that case partial, though often extremely efficient. The possession of chelae is not con- fined to the first pair of so-called peraeopods, although it is seldom elsewhere that they attain a monstrous develop- ment. They may occur on any of the pairs, and on several in the same animal. In connection both with the maxilli- peds and the perseopods there are developed in great variety of form the branchiaa or gills, also the plates of the marsupium, wherein, in some groups, the eggs are retained for a time after their discharge from the ovaries ; and again, in some groups, the exopods are developed as swim- ming organs. The vulvse, or uterine openings of the female, belong to the sternal, that is the ventral, side of the twelith segment, while the genital openings of the male occupy a similar position in the fourteenth segment. In those Crustacea which have the basal joints of each pair of legs brought close together, the openings in ques- tion have been transferred from the wall of the trunk to the first joint in each of the last pair of legs in the male, and of the antepenultimate pair in the female. 15, 16, 17, 18, 19, 20. The remaining segments belong to the tail or caudal portion of the animal, which has been termed the pleon or swimming-part, a convenient and often a very appropriate name, although on the other hand there are plenty of crustaceans which do not and cannot use the pleon to swim with. The first five of these segments frequently have appendages that are really natatory and may properly be called pleopods, swimming- feet. But some or all may be wanting, or rudimentary, 4-6 A HISTORY OF RECENT CRUSTACEA or devoted to other purposes. They may be partially or entirely branchial. Among the Stalk-eyed Crustacea they are often used in the female for retaining the eggs during an early period of development or hatching. In the -Amphipoda the fourth and fifth pairs are more or less adapted for springing, and bear the name of uropods, or tail-feet. This name is also given to the appendages of the twentieth segment whenever they are present. These are prominent features in the Cumacea and most other Edriophthalma, and in the Macrura they combine with the telson to form the powerful tail-fan, for which Mr. Spence Bate has proposed the Greek name rliipidura (see Plate X.). In the Copepoda there is a ' caudal furca,' homologous with the caudal rami in the Nebaliida3, which must be distin- guished from the terminal uropods of the higher Crustacea, as ' being not true limbs, but more properly representing a bipartite terminal segment.' l 21. The telson is extremely variable in form and relative size, and sometimes by coalescence with the pre- ceding segment shows little trace of independent exist- ence. The intestinal canal opens on its under side. It is sometimes deeply cleft, as though the two terga, or dorsal plates, of a body-ring had come apart. To prove its claim to be regarded as a segment, the most effective argument would be to show that it sometimes carries appendages after the fashion of all the other segments. Bell, in the ' British Stalk-eyed Crustacea/ says that he has frequently observed appendages to the telson of the common prawn, Leander serratus (Pennant), ' in the form of extremely minute points attached to the very exti'emity of the segment, and moveable.' Spence Bate says, ' In some genera, or even families, the telson is posteriorly rounded, as in the Astacidte; in others it is anteriorly hard and calcareous, and posteriorly soft and membranous, as in the Synaxidea, a circumstance that is suggestive of a distinct relationship of the two parts, the anterior Avhich carries the anus belonging to the normal somite, 1 Sars. Report on the Phyllocarida collected by H.M.S. Challenger, p. 35. INTERNAL DIFFERENCES 47 while the posterior portion represents its appendages. This idea is still more strongly suggested in the genus Cheiroplatea, where the separation of the posterior from the anterior division is clearly defined by a distinct mem- branous articulation, and the posterior portion is divided into two lateral lobes.' 1 The older genus Porcellana is even more to the purpose than Cheiroplatea, and Miss J. M. Arms, in the Manual before referred to, considers that it settles the question. Comparing a species of it with the lobster, ' This curious little crab,' she says, ' possesses a telson with an unmistakable pair of appendages attached to it, proving that this part is really a ring whose appen- dages are wanting in the lobster.' It must, however, be remarked that neither in the Porcellanidte nor in the Gala- theidge do these apparent appendages of the telson ever become freely articulated with it, and as they are the last to put in any appearance at all, and then only in a late stage of the animal's development, it remains a question whether they may not be dividing lines of the telson rather than appendages arising from it. In the internal organs of crustaceans the differences are as great as in the external. One writer has even undertaken to classify the Brachyura according to the structure of their stomachs. Unless this part of the organism were tolerably complicated, it will be easily under- stood that it would not afford sufficient variations for such a purpose. But though, for establishing a really natural system, every stage of an animal's development and all its parts ought to be studied and taken into account, surely a systematist ought to aim at founding his classification as far as possible on the most accessible stages and the parts most easily observed. At any rate the general student will have little inclination to arrange his collec- tion by investigating; in the different specimens the walls of the stomach and the teeth and hairs within it, although he may occasionally be pleased to observe in that of the lobster the three horny-looking grinders, the central one 1 Spence Bate. Report on the Macrura collected by H.M.S. Chal- lenger, p. xlviii. 48 A HISTORY OF RECENT CRUSTACEA of which has from of old been fancifully called ' the lady in the chair.' The character of all the internal organs of FIG. 1. A lobster's stomach opened to show the teeth, the central one of which has been supplied with eyes, nose, and mouth, to represent 'the lady in the chair.' [Herbst] a crustacean, as exemplified in the crayfish, has been already discussed in detail by Professor Huxley in a pre- vious volume of this series. It may here, therefore, suffice to recall that in a crustacean the heart is dorsal, the nerve- chain, with the exception of the brain, ventral, and the alimentary canal central, having in proximity the hepatic lobes or liver, and the testes and ovaries. Some of the more or less striking peculiarities which prevail in different groups in regard to these organs are reserved for mention as occasion offers in the description of the several sub- orders and their families. The following table supplies a synopsis of all the leading groups of the Crustacea. The literal meaning of the various names has been explained in the first chapter : A TABULAE VIEW 49 Malacostraca. Class. CRUSTACEA. Sub-classes. Entoniostraca. Thyrostraca (or Cirripedia). Gi;antostraca. MALACOSTRACA. Orders. Podophthalma. Edrioplithalma. Sub-orders. Brachyura. Macrura. Schizopoda. Stomatopoda. Sub- orders. Cumacea. Isopoda. Amphipoda. Branchiopoda. ENTOMOSTRACA. Orders. Ostracoda. Copepoda. Sub-orders. Phyllocarida. Phyllopoda. Cladocera, Branchiura. Sub-orders. Podocopa. Myodocopa. Cladocopa. Platycopa. Sub-orders. Gnathostoma. Poecilostoma. Siphonostoma. GrIGANTOSTRACA. Orders. Merostomata. Xiphosura. Trilobita. Thoracica. I Sub-orders. Pedunculata. Operculata. THYROSTRACA (CIRRIPEDIA). Orders. Abdominalia. Apoda. Rhizocephala. E 50 A HISTOKY OF HE CENT CRUSTACEA CHAPTER V THE SUB-CLASS MALACOSTRACA THE head and trunk are together composed of thirteen, or, if an ophthalmic ring be included, of fourteen seg- ments. The caudal part or pleon is composed of six seg- ments and a telson. The trunk is clearly distinguished from the pleon, but some part of it is always more or less closely united with the head. To every segment normally belongs a pair of jointed appendages. The eyes are either pedunculate, and limited to two in number, with rarely a pair of accessory ocelli, or they are sessile, and then gene- rally two, but sometimes four, or with the components variously distributed. There are two pairs of antennae, a pair of mandibles, and two pairs of maxillas. Of the next eight pairs of appendages, from one to three are maxilli- peds, organs of the mouth, the remainder, from seven to five in number, being prehensile or locomotive. All these are typically seven-jointed. Like the second antennas and second maxillas they may either have or be without an exopod on the second joint, and they may also have or be without an epipod on the first. The six pairs of appen- dages of the pleon, when present, generally have an exopod. The last pair almost always differs in character from, the rest. The paired appendages of the mouth work from the sides, the oral aperture itself being fringed by the labrum or upper lip above, and the bifid labium or lower lip below. A short oesophagus leads up into the stomach. The intestinal tube terminates in the under side of the telson. The heart which is dorsally placed has lateral openings for the entrance of the blood that has been oxygenated in the branchias. These slits are in one, two, SHOET TAILS 51 or three pairs, only in the Squillidas exceeding that num- ber. The ganglia of the same pair are situated' close to one another, though the commissures may stand a little apart. By the dorsal and lateral extension backwards and generally also forwards of one (or two) of the cephalic segments a shield or carapace is formed covering at least some part of the trunk and sometimes all of it. The above characters will suffice for a descriptive defi- nition of the Malacostraca, but it may be proper to remind the reader that the segments are sometimes so intimately coalesced that their separate identity is entirely obscured, and that moreover almost any pair of the appendages, even one so seemingly indispensable as the mandibles, may in certain cases be missing. Absence of eyes is by no means infrequent, and the telson, though perhaps never properly speaking absent, is often, by its close union with the pre- ceding segment, so withdrawn from recognition, that in practice it is spoken of as absent. Order 1 . Podophthalma. In this order there is normally a pair of compound eyes on movable stalks, the eyes being sometimes absent but never sessile ; the dorsal shield or carapace extends back over the ninth segment or further.. Sub-order 1. Brachyura. The carapace extends over the whole head and trunk, with occasional exception of the trunk's ultimate and pen- ultimate segments, and is longer than the pleon. In the carapace are excavated orbits and fossettes, hollows respec- tively adapted to receive the stalked eyes and the short first antennas. The third maxillipeds have some of the joints broad and flat, and they form a more or less com- plete operculum to the well-defined mouth cavity. The following pair of appendages are perfectly chelate limbs, commonly called the chelipeds. The next four pairs are adapted for walking or swimming, or rarely may have a prehensile character. In the sternal plastron, or breast- E 1 52 A HISTORY OF RECENT CRUSTACEA plate, the coalesced ventral plates of the last five seg- ments of the trunk are distinguishable, and three earlier segments are obscurely represented. It is never entirely linear. The vulvas of the females are generally placed upon it, but in some groups are transferred to the basal joints of the ante-penultimate legs. The pleon is of sub- ordinate size, usually reflexed against the concavity of the plastron, in the male generally narrow and pointed, with only one or two pairs of pleopods, in the female broad, with four pairs of pleopods. The basal joint of the first antennae contains auditory hairs but no otoliths. In this definition the Anomura apterura are included. To the dry bones of definition must be added an even less appetising explanation of terms in common use for the description of genera and species. The orbital regions of the carapace speak for themselves as being those which contain the eyes. The ' front ' lies between them. Behind it on the under surface are the fossettes of the first an- tennae, followed in the median line by the epistome, the buccal or oral frame, and the sternal plastron. The second antennas are placed outside of and a little behind the first. The ' hind margin ' of the carapace separates the trunk from the pleon, and lies between the first joints of the last pair of trunk-feet. Between it and the orbits are the lateral margins, 'each of which is subdivided into an antero-lateral and a postero-lateral portion forming, when not continuous, the epibranchial angle. The dorsal sur- face of the carapace is marked by several grooves cor- responding with the insertions of muscles -underneath, and also forming the boundary lines of regions which roughly coincide with the positions of important internal organs. Along the centre lie the gastric, cardiac, and intestinal regions, respectively over the stomach, heart, and intes- tine. The hepatic regions over the liver flank the gastric region on either side in front, and behind these lie the two branchial regions, the ' cervical groove ' being that which separates the gastric and hepatic regions from the cardiac and branchial. On the under side the pterygostomian re- gions, ' the wings of the mouth,' lie between the antero- MASKS AND FACES lateral margins of the carapace and the buccal frame- Milne-Edwards remarks that the grooves are often em- phasised about the middle of the carapace, so as to pro- duce the appearance of the capital letter H, the transverse FIG. 2.Ethusa mascarone (Herbst). [Herbst] line being the upper boundary of the cardiac region. In some cases the grooves are so arranged as to represent very strikingly a human countenance or the caricature of one, as in the Masked Crab of Great Britain and the grimac- ing Ethusa mascarone of the Mediterranean, which is here shown as depicted by Herbst. Such likenesses the old writers were not at all disinclined to accentuate. The Brachyura are divided into tribes, in regard to which, however, there is not at present any absolute agree- ment among naturalists. We shall here arrange them under the names Cyclonietopa, Catoinetopa, Oxyrrhyncha, Oxystomata, Anomala. It is melancholy, but scarcely avoidable, that an alternative list of names should have to be mentioned, for these tribes in the same succession may be called Cancroidea, Ocypodiidea, Maioidea, Leucosiidea, and Anomura apterura. The subjoined table will be use- ful for reference. 54 A HISTORY OF RECENT CRUSTACEA BRACHYURA. Tribes. Cyclometopa Catometopa Oxyrrhyncha Oxystomata Anomala . Legions. . Cancrinea Cyclinea Corystinea Thelphusinea . Maiinea . Parthenopinea . Drominea Ranininea Families. Cancridse, Trapeziidre, Portunidre, Podophthalmidse. Cyclidas. Corystidas. Thelphusidns. Gecarcinidre. Ocypodida?. Grapsidae. Pinnotheridas. Inachidce, Maiidae, Periceridte. Parthenopidffi. Calappidte. Matutidae. Leucosiidns. Dorippidse. Dromidne, Homolidre. Raninidae. EOUNDHEADS 55 CHAPTER VI TRIBE I. CYCLOMETOPA THE name literally means ' those of a circular forehead.' In these Crustacea the carapace is often of a breadth greater than the length, wide and regularly arched in front, more rarely quadrate or suborbicular, but not rostrate. The epistome is short, transverse. The first antennas are in general transversely folded. The third maxillipeds have the fifth joint articulated at the apex or the inner front angle of the fourth (except in Pirimela). There are nine pairs of branchias, with their efferent channels opening at the sides of the endostome or palate. The verges of the male are inserted at the bases of the last legs of the trunk, Milne-Edwards states that the different ganglia of the trunk form a sort of circular ring,, of which it is often easy to distinguish the constituent elements, and that the two halves of the liver remain distinct without a median lobe. The tribe has been subdivided into four legions Cancrinea, Cyclinea, Corystinea, Thelphusinea, in de- fining which I shall follow the safe guidance of Mr. E. J. Miers, as afforded in his report on the Brachyura collected by the Challenger. Legion 1. ^Cancrinea. The buccal cavity is usually well defined. The flagella of the second antennaa are not greatly elongated. The seventh joint in the walking-legs is generally unarmed. It is either stiliform or in the last pair expanded into an 56 A HISTORY OF EECENT CRUSTACEA ovate swimming organ. The species are marine or littoral. This legion contains four families Cancridee, Trape- ziidas, Portunidee, Podophthalmidse. Family 1. Cancridce. The carapace is commonly transverse and convex, with the antero-lateral margins arcuate, and armed with several lobes, teeth, or spines. The ' front ' is of moderate width, in general not projecting over the first antennse and the bases of the second, the latter being seldom excluded from the inner hiatus of the orbits. In this family are included about half a hundred genera, some widely and conspicuously distinct, others separated by fine and almost inappreciable differences. Thus Mr. Miers observes of Xantho (Leach, 1813), that ' it is connected by almost insensible gradations on the one hand with Loplioxantlms and Xanthodes, on the other with Panojteus and Eurypanopeus.'' Quite recently the genus Panopeus, H. Milne-Edwards, 1834, has been re- viewed by James Benedict and Mary Rathbun. They recognise' in it thirty-eight species, and re-include within its boundaries Eurytium, Stimpson, 1859, and Eurypano- peus, A. Milne-Edwards, 1880, considering that they have been separated from the parent genus on grounds in- sufficient or untenable. It will, however, be quite be- yond the range of such a manual as this to enter into all the miuutias of generic distinctions. Far less can the characters of innumerable species be discussed. Only the specially typical or the specially anomalous forms may court a passing attention. Here and there a comparison, a description, a comment, may indicate the variety of details upon which classification is founded, or may sug- gest the endless opportunities for the exercise of keen eyes and acute minds, which the subject provides. Those whose scientific zeal is limited to the desire of having the specimens in a cabinet rightly arranged and ticketed with their proper names are often puzzled and HOW GENERA ARE GENERATED 57 exasperated to find that there is practically no finality in, these matters. It is important to remember that this cannot be helped, so long as knowledge is in the stage of growth, the stage in which it is most acceptable to the human intel- lect, by continually holding out the invigorating hope of new acquisitions. In the progress of science some animal hitherto unknown or little noticed attracts the attention of a naturalist. Describing some of its salient features, he makes it the typical species of a new genus. In course of time many other animals are found to have characters almost identical, and they constitute the various species of the same genus, till the number of them becomes so large that they are perhaps at first grouped in lettered or num- bered sections, to which presently names are given as sub- genera, and these in turn are raised to the rank of genera, and sometimes eventually to higher grades in the system. At each successive improvement there comes a displace- ment of the old names, and for the accurate designation of specimens the unskilled are placed at greater and greater disadvantage. There was a time when all the Crustacea were included among insects, but to call a lobster an in- sect would now be regarded as a proof of ludicrous igno- rance. The existing genus Cancer is an absurd little remnant of that which was originally established by Linnaeus, and which has been gradually subdivided into a long array of genera, and families, and legions, and sub-orders, and orders. Bell, in 1853, in his ' British Stalk-eyed Crustacea,' says, ' There is but one species of this genus, as now restricted, native of the shores of this country, or indeed of Europe, all the others being South American.' He refers, however, to the species discovered by Say, which belong to the East Coast of North America. The great eatable crab of our own shores is well known. Dr. Leach remarks that ' at low tide they are often found in holes of rocks, in pairs, male and female, and if the male be taken away, another will be found in the hole at the next recess of the tide. By knowing this fact, an experienced fisherman may twice a clay take with little trouble a vast number of specimens, after having once 58 A HISTORY OF EECENT CKUSTACEA discovered their haunts.' Mr. Couch found that this referred to the mating time, which occurs just after the female has cast her coat, her new shell being still soft. It is easy to understand why the exuviation of the male takes place at a different period, as otherwise the pair would be defenceless together. Of this Cancer pagurus, Linn., small specimens are often sheltered in considerable numbers in cavities wrought in the vast masses of the sand-tubes of the marine worm Sdbellaria alveolata. Cancer irroratus, Say, is the commonest species of the genus in America. It is exceedingly like the European species, but smaller, with the chelipeds less bulky, and dis- tinguished by a strong tooth on the fifth joint. It is said to be common under the large rocks near low-water mark, often lying nearly buried in the sand and gravel beneath them. " It is also frequent on sandy shores, and occurs in the tidal pools, where, according to Professor Verrill, ' the comical combats of the males may sometimes be witnessed.' Miss J. M. Arms founds upon it the following description of a crab's method of walking : ' The legs of one side are used to push with, and those of the other to pull with, when the crab is in motion. Those of the same side do not, however, all move together, but alternately, so that there is no halting in their gait ; some of the legs are always in the act of taking new steps, and by shoving and pulling in unison a continuous motion is kept up. This crawling by means of jointed appen- dages can be imitated after having once seen a live crab. Cross the two wrists side by side, placing the fingers down on a level table ; bind the wrists by an elastic band, hold them well up from the table, so as to show the fingers. Then let one set crawl while the other pushes, so as to keep up a continuous motion sidewise without assistance from the arms. The terminal sections of the legs show wear only on the points where these are inserted in the ground.' It will subsequently be seen that there are some crabs which are by no means limited to the slow progression denoted by the word crawling. FACT AND FICTION 59 Say established the species Cancer irroratus in 1817, but in 1859 Stirnpson discovered that under one name Say had combined two species, having been misled into matching the male of Cancer irroratus with the female of Cancer borealis. The differences between the sexes which often exist in Crustacea have more commonly led naturalists into the opposite mistake of instituting a separate species for each sex. Cancer borealis, Stimpson, occurs in the same localities as Cancer irroratus, only being a heavier and more massive species it does not equally court shelter and retirement, but will rest entirely exposed on bare rocks and ledges, or clinging to weeds amid the onset of the waves. Yet the strength of its shell does not save it from the gulls and crows which take advantage of its venturesome position to carry it off for their own con- sumption. It is not only the sexes of the adult crustaceans that often differ considerably in appearance, but in many in- stances between the egg and maturity there are stages to be passed through in which the forms of the young are so startlingly different from those of their parents that they have been placed in different genera, until the relationship was eventually proved or made probable. To these lar- val stages various names have been given, some of them borrowed from the names of the supposed genera to which the young animals had been at first assigned. The Dutch naturalist, Martin Slabber, in 1769, was the first to publish an account of a crustacean metamorphosis so striking that, as he says, had he not himself witnessed it, he should have placed the two forms in different genera. Yet this singular observation was left barren, until in 1823 Mr. Vaughan Thompson was induced to follow it up, with results that have since been far-reaching. One very curious circumstance in this history is that the two forms which Slabber figures evidently do belong to perfectly dis- tinct groups, the first or Zo'ea form to the Brachyura, and the second to the Macrura. Bell, in the Introduction to his 'British Stalk-eyed Crustacea,' reproaches Thompson for corning to the conclusion ' that Slabber lost his Zoea, in GO A HISTORY OF RECENT CRUSTACEA changing the sea-water, and that the new form came from the added portion.' The second form has been shown to correspond very exactly with the larval stage of a prawn, and from this Bell weakly argues that the observation of Slabber was correct, although the first form, as Bell had reason to know, was the larval stage of a crab, and in this Slabber correctly observed the gradual dwindling of the horns of the carapace. The minuteness and transparency of these infants and the readiness with which they perish will account for the confusion in regard to the principal change into which he appears undoubtedly to have fallen, but it is remarkable that such an error should have been in close agreement with the real facts of the case, that a discovery apparently so full of interest should have been neglected for half a century, and that then, when at length it was placed tipon a solid foundation, the facts should have been hotly and stoutly disputed for a long series of years. In 1837 Milne-Edwards was still undecided on many of the details of the question, but as to the state- ment made by Vaughan Thompson in 1835 that the great French naturalist had been deputed by the Academy of Science to investigate the development of the Crustacea, that he had passed a summer in the Isle of Re for that purpose, and had come to the conclusion that the Crustacea are born in their permanent forms, in all that, Milne- Edwards retorts, there is not a word of truth. He had never been in the Isle of Re, he had never denied that some Crustacea underwent considerable changes, and he could only hope that Thompson was more careful in his observations than in his quotations. Notwithstanding this sharp denial, Bell in 1853 still sends Milne-Edwards to the Isle of Re, and wonders that observations which he never made should have led him to conclusions which he did not entertain. The larval stages of the American Cancer irroratus have been studied by Professor S. I. Smith. As might have been expected, they agree very nearly with those of the European Cancer parjurus. In its latest stage the Zo'da still has a frontal and a dorsal spine that are WATER-BABIES 61 very conspicuous, but at an earlier period it has much longer spines on the carapace, and as yet no rudiments of the legs of the trunk or pleon. After many months they attain the final Zoea stage, in which the terminal segment of the pleon is very broad, and divided nearly to the base by a broad sinus, formed by long spiniform diverging processes, at the base of which the sinus is armed with six to eight spines on each side. Shortly before the change into the second or Meyalopa form, ' they were not quite so active as previously, but still continued to swim about until they appeared to be seized by violent convulsions, and after a moment began to wriggle rapidly out of the old zoea skin, and at once appeared in the full megalops form. The new integument seems to stiffen at once, for in a very few moments after freeing itself from the old skin the new megalops was swimming about as actively as the oldest individuals. In this megalops stage the animal begins to resemble the adult. The five pairs of cephalothoracic legs are much like those of the adult, and the mouth-organs have assumed nearly their final form. The eyes, however, are still enormous in size, the carapace is elongated and has a slender rostrum and a long spine projecting from the cardiac region far over the posterior border, and the abdomen is carried extended, and is furnished with powerful swimming legs as in the Macroura.' Professor Smith observed a few instances of the change from the megalops or Megalopa stage to the young crab. ' The little crab worked himself out of the megalops skin quite slowly. For a short time after their appearance the young crabs were soft and inactive, but the integument very soon stiffened, and in the course of two or three hours they acquired all the pugnacity of the adult. They swam about with ease, and were constantly attacking each other and their companions in the earlier stages.' Professor Smith has remarked that in ' The Crayfish,' fig. 74 represents the Zoea and Megalopa stages of Carcinus mcenas, not, as stated by a misprint, those of Cancer pagurus. 62 A HISTORY OF RECENT CRUSTACEA If the tiny young of the Crustacea attack and destroy one another, it is not for want of innumerable other enemies fitted to keep their numbers in check. As far as the timidity of human experience can decide, the Crustacea in general, though by no means particular as to the food they consume, invite rapacity by the agreeable quality of the food they supply. The enormous spines of the very young and the strong armature of the adults have probably been called into existence in consequence. Where these are wanting or' inadequate, the life of the species has been protected by extreme fertility. In Geryon quinquedens, Smith, for example, it has been computed that one speci- men was carrying no less than forty-seven thousand eggs, and there are other species reckoned to be at least twice as prolific. To the extensive genus Xantho Bell assigns three British species, naming them florida, rivulosa, and tuber- culata. But, Montagu's flondus having lapsed as a syn- onym, the first of the three should be named Xantho incisus, Leach. The second, on Bell's own showing, ought to be called Xantho hydrophilus (Herbst), and of this Couch's tuberculata is now held to be a variety. Ozius, Milne-Edwards, 1834, was a genus established to receive certain species found in the Indian and Austra- lian waters. The name had been given much earlier by Dr. Leach, but without published description. It presents a peculiarity by help of which the large family of the Cancridas is divided into two sections. The space between the front margin of the buccal frame and the mouth itself was called by Milne-Edwards the prelabial space. By English writers it is called the endostome or palate. In Cancer, Xantho, and many other genera, this endostome is without distinct longitudinal ridges defining the apertures of the efferent branchial channels, whereas in Ozius, Pilum- nus, Eriphia, and others, it has these ridges. Pseudozius, Dana, 1851, is, as the name implies, a genus that might be mistaken for Ozius, but the crests of the endostome do not quite reach the upper margin of the buccal frame. In 1881 the species Pseudozius Mellissi MUCH LEARNING 63 from St. Helena was carefully described by Mr. Miers, who pointed out its resemblance to and differences from XantJw Bouvieri, A. Milne-Edwards, a species from the Cape Verd Islands. In 1886 Mr. Miers re-described it, and gave a figure of it in his ' Challenger Report,' but he then placed it in a new sub-genus Euryozius, entitling it c Pseudozius bouvieri, var. mellissii,' in a hesitating manner identifying it with the species Xantho Bouvieri of A. Milne-Edwards. In 1888 Professor Th. Barrois, in his catalogue of the marine Crustacea of the Azores, once more describes this species, and gives a beautiful figure of it in its natural colour of bright orange-red, with black tips to the cheli- peds. He and Mr. Miers are in exact agreement in their descriptions, as two such excellent naturalists were likely to be. But Professor Barrois calls the species Ozius Edwardsi, and explains that he had submitted it to the highly competent judgment of M. Alphonse Milne-Edwards, who pronounced it to be a new Ozius, of which he had himself obtained a specimen at the Canaries during the expedition of the Talisman. It will be consoling to the beginner and the amateur, when involved in perplexity amid species that they cannot name or can only name at random, to find the past masters of the science thus en- tangled as it were in their own web. For it must not be forgotten that Alphonse Milne-Edwards is acknowledged to be ' the highest authority on the Brachyura,' l and yet he leads Barrois to make a new species of that which had been twice described and twice named by Miers, and which had probably been already named and described by Pro- fessor Milne-Edwards himself. The instance is significant of the stress, to which the highest powers must sometimes prove unequal, of keeping in mind each individual species of the vast multitude now known, and each individual chapter of the vast literature which records them. Barrois mentions an interesting peculiarity in this ele- gant crab. The carapace along the antero-lateral margins is obliquely striated on the under side with fine parallel grooves, in correspondence with which the fifth joint or 1 Miers, Challenger Report, p. 146. 64 A HISTORY OF EECENT CRUSTACEA wrist of the chelipeds lias a long sharp crest aid the rapid rubbing of this crest against the stride produces a shrill sort of stridulating noise such as a grasshopper makes by drawing the thighs of its hind legs over the salient nervures of its wing-cases. Pilumnus, Leach, 1815, is represented in Great Britain by the single species Pilumnus hirtellus (Linn.), but fnr the world at large more than eighty forms have b described under separate specific names, and still the discriminating criticism of some future monc In this genus, as at present defined, the antero-laudral margins are normally armed with spines instead of the usual teeth, and the pleon is seven-jointed in both sexes. But when the description and figures of Pilumnus xan- thoides, Krauss, 1843, are examined, they exhibit not spines but rounded teeth or lobes on the antero-lateral border, and a five-jointed pleon in the male. Thus there is primd facie reason to suppose that this species ought to be removed to some other genus. Otherwise the boun- daries of the existing genus must be enlarged, whereas for convenience they rather require to be narrowed. Pirimela, Leach, 1815, like Pilumnus, is represented in Great Britain only by a single species, Pirimela denticulata (Montagu), which occurs also in the Mediterranean, but, unlike Pilumnus, it is not represented by any other species elsewhere. In this genus the pleon of the female is seven- jointed, but that of the male five-jointed, the three middle joints being coalesced into a single piece. It differs from all the rest of the Cyclometopa in the character of the third maxillipeds, for here the fourth joint receives the articula- tion of the fifth on its inner instead of on its apical margin. Family 2 . Trapeziidce. '' Carapace depressed and nearly quadrilateral, smooth, with the postero-lateral angles truncated, the dorsal regions not defined ; the antero-lateral margins are straight, form a right angle with the front, and are entire or have but one tooth (the lateral epi-branchial tooth) developed. The THE COMMON SHORE CEAB 65 front is -rizou ,al, broad, lamellate, and projects over the antennuies and bases of the antennas, which are widely excluded from the orbit's.' The genera are Trapezia, Latreille, 1825, Tetralia, Dana, 1851, and Quadrella, Dana, 1851, names indicative of the prevailing shape. The species in general are small pnd confined to the warm seas. According to the Russian 'ter, Paulson, 1875, the lower antennas of Tetralia re- that the last clause of the above-quoted definition \ be cancelled. Family 3. Portunidce. The carapace is depressed, moderately transverse, and usually widest at the last antero-lateral marginal spine. The 'front' is horizontal and not spatuliform (see p. 71). The orbits and eye- stalks are of moderate length. The spine or tooth at the outer angle of the orbit does not project laterally beyond the teeth of the antero-lateral margin, of which more than one, usually from five to nine, are developed. The last legs of the trunk are commonly adapted for swimming, with the seventh joint ovate, flatly expanded. The Portunidas include about half as many genera as the Cancridas. Oa/rcw/uSj Leach, 1813, has the seventh joint of the fifth legs narrowly lanceolate. The species Carcinus mcenas (Pennant) is the most obtrusive of all the British Brachyura. Its numbers justify its English designation as the Common Shore Crab ; its extremely vivacious movements and its reckless audacity when brought to bay justify its scientific title and the corresponding French name for it of Grdbe enrage. In the early part of this century Leach stated that it was sent to London in immense quantities and eaten by the poor. Professor Stalio says that at the present day it is a considerable source of food-supply to the humbler classes on the shores of the Adriatic, that in the soft state, just after the shedding of the skin, it is welcome at the tables of the rich, and that the Istrian fishermen pound it up and use it as a most attractive bait to the sardines. On F 66 A HISTORY OF RECENT CRUSTACEA the other hand, complaints are made by English writers of the mischief which it does to fish already captured, and Dr. Hoek accuses it of the truly detestable crime of in- vading the oyster beds, and eating the young oysters while their shells are still soft and easy to break. In attacking the adults, it is itself sometimes caught by the snapping down of the powerfully hinged valves. The only other species of this genus known is the American Ga/rcinus granulatus (Say), and even this may not be really distinct from the European form. Portunus, Fabricius, 1798, has the last two joints of the fifth legs "dilated and compressed, and the last joint ovate. It is by this formation that many of the Portu- nidae are qualified as swimming crabs. In the Caribbean Sea, and among the gulf weed in the tropical Atlantic, Mr. Gosse observed them shooting through the water almost like a fish, ' with the feet on the side that happens to be the front all tucked close up, and those on the oppo- site side stretched away behind, so as to hold no water, as a seaman would say, and thus offer no impediment to the way.' Our British species swim with less facility, and are often called fiddler crabs, because, as Mr. Gosse explains, ' the see-saw motion of the bent and flattened joints of the oar- feet is so much like that of a fiddler's elbow.' The beauti- ful Velvet Crab, Portunus puber (Linn.), called in the Channel Islands the Lady Crab, is for ordinary purposes sufficiently described by Bell in the ' British Stalk-eyed Crustacea,' together with six other species of the genus that have been obtained in the waters of Great Britain, namely depurator (Linn.), corrugatus (Pennant), arcuatus and pusilhis, Leach, holsatus. Fabricius, and its near ally marmoreus, Leach. To these Canon Norman has added Portunus tuberculatus, Roux, from the Shetland Isles. He remarks on the singularity of the circumstance that this and many other southern forms should be found in the deep Shetland waters, though they are not known from localities between those waters and the Mediterranean. Portumnus, Leach, 1814, both by name and structure, closely approaches the preceding genus, but it has the THE AMERICAN LADY-CRAB 67 last joint of the fifth legs lanceolate. The British species which Bell names Portummi* variegatus^ Leach, he ought in accordance with the rules of priority to have called Portumnus latipes (Pennant). In distinguishing Por- tumnus from the closely allied Platyonichus, Latreille. 1818, Bell or his printer has made a confusing mistake by attributing to Plafyonich/us the acutely lanceolate ter- minal joint in the fifth pair of legs, and the broad oval, very much rounded joint to Portumnus, instead of putting the contrast the other way round (see Plate II.). He men- tions that in Portumnus, as in many other Portunidse, the- pleon of the male is five-jointed, whereas in Plafyonichus- it is seven -jointed. Unfortunately this distinction, which would have been so convenient, only applies to two out of the three species which are now allotted to the latter genus, namely to Platyoniclius bipustulatus, Milne-Edwards, and to Platyoniclius iridescens, Miers, a species in which the legs- are said to be beautifully iridescent. Platyoniclius ocellatus was first described in 1799 by Herbst, who records its habitat in the words, ' Das Yater- laiid ist Long-Eiland bey Newyorck.' Both New York and the ' Lady Crab ' of America have come to be better known than they were in the time of Herbst. Yen-ill and Smith, in their valuable report on the inverte- brate animals of Yineyard Sound, give a figure of the crab and many interesting particulars. It is, they say, perfectly at home among the loose sands at low-water mark, and also abundant on sandy bottoms off shore. It is a rapid swimmer, and was not unfrequently taken on the surface- of the sea. ' When living at low-water mark on the- sand beaches it generally buries itself up to its eyes and antennae in the sand, watching for prey or on the look-out for enemies. If disturbed, it quickly glides backward and downward into the sand, and disappears instantly. This power of quickly burrowing deeply into the sand it pos- sesses in common with all the other marine animals of every class which inhabit the exposed beaches of loose sand, for upon this habit their very existence depends during storms. By burying themselves sufficiently deep F 2 68 A HISTORY OF RECENT CRUSTACEA they are beyond the reach of the breakers.' ' The lady- crab is predacious in its habits, feeding upon various smaller creatures, but like most of the crabs it is also fond of dead fishes or any other dead animals. In some localities they are so abundant that a dead fish or shark will in a short time be completely covered with them, but if a person should approach they will all suddenly slip off backwards and quickly disappear in every direction be- neath the sand ; after a short time, if everything be quiet, immense numbers of eyes and antennas will be gradually and cautiously protruded from beneath the sand, and after their owners have satisfied themselves that all is well, the army of crabs will soon appear above the sand again, and continue their operations. The colour of this crab is quite bright, and does not imitate the sand, probably owing to its mode of concealment. The ground-colour is white, but the back is covered with annular spots formed by specks of red and purple. It is devoured in great numbers by many of the lai-ger fishes.' Polybius, Leach, 1820, is closely related to the three preceding genera, and like the last has the capacity for swimming highly developed. The single species, Polybius Henslowiij Leach, is European, and is distinguished by having much compressed joints not only in the last pair of legs, but also in the three preceding pairs. It is said to pursue fishes so active as the mackerel, to fasten upon them with its sharp pincers, and to hold on till they succumb. The fishermen in consequence call it the nipper crab. Probably it is only fish that are terrified or hampered by the proximity of the fishing-net that fall vic- tims to its agility. The Prince of Monaco records that on one occasion, off the coast of Spain, his bursting trawl-net brought up from a considerable depth at a single haul about five thousand fine specimens, which produced an animated scene on board his yacht by nimbly fastening with their cat-like talons on to the bare toes and fingers of the crew. Scylla, de Haan, 1833, belongs to a group of genera in which the carapace is very broad, and the antero-lateral margins are armed with nine or more teeth. Some of the SCYLLA AND CHARYBDIS 69 species are strikingly handsome, both in shape and colour. Scylla serrata (ForskSl), a widely distributed Indo-Pacific species, is said by Krauss to be the largest and strongest of the South African Crustacea. The chelipeds of the male are much larger and more powerful than those of the female, and colossal in relation to the carapace. The damaged limbs and bodies covered with scars, uniformly exhibited by male specimens, are adduced in support of the inference that their combats one with another are not a little intemperate. On the muddy coasts of the Bay of Natal, Krauss says, this species lives in great deep holes, and wears the dingy earthy colour of its residence. They sit at the openings of their holes when the tide is coming in to snap up the food which it brings them, and to sun themselves when the tide is going out. At any one's approach they vanish into their holes in a moment, or, if their escape is cut off, they raise themselves up on their hind legs, and by clashing together their powerful claws endeavour to scare away the intruder. By driving a spade into their slanting tunnels their retreat may be cut off,- or they will clutch at the proffered point of a stick and may so be drawn out, but the Caffres, who consider them dainty food, capture them by spear-throwing. Charybdis, de Haan, 1833, belongs to a group of genera in which the carapace is said to be only moderately broad, and the antero-lateral margins have seven teeth or fewer. However, in Charybdis cruciatus (Herbst), the carapace is of very considerable breadth. The colouring of this species is highly remarkable. Herbst in 1796 gives a fine picture and a glowing description of one of the specimens which he received from the East Indies. The colours in the plate are vivid, but it cannot be said that they tally in all respects with the verbal account. According to the latter, the carapace from the front to beyond the middle of the field is of blood-red hue upon a yellowish ground, and marked with the figure of a great yellowish white cross. Down the sides run broad stripes of greenish red, shading off into grey. The upper surface of the chelipeds is marbled with yellow and red, the hands 70 A HISTORY OF RECENT CRUSTACEA having deep red patches and interlacing lines. The following pairs of feet are yellowish with faint red lines, the last pair being marbled with red, its joints very broad, and the last of them thin and membranous. By -some writers this species is called Goniosoma cruciferum (Fabri- cius). They would displace de Haaii's Charyldis, not because of any pre-occupation of that name, which would have afforded a just reason, but because a different name Charybdea had been previously employed, which is no reason at all for cancelling Charybdis. Again, they would displace the earliest specific name cruciatiis as inappro- priate, whereas, they argue, the name cruciferum, given by Fabricius, is in accordance with the great pale cross marked upon the carapace. It is true that Herbst pro- bably tortured the meaning of cruciatus, but it is quite clear that he intended it to bear the sense of cruciferum, and even if he had chosen to regard his crab as fixed to a cross instead of regarding the cross as fixed on the crab, it would not have justified any tampering with the name and the rights of priority. It is perhaps this species that suggested the story found in the old writers that on one occasion, to calm the sea, Xavier threw a crucifix into it, and that this was afterwards restored to him by a crab. Sathynectes, Stimpson, 1871, with a name that means ' the deep swimmer,' is closely akin to Charybdis, but its antero-lateral margins have only five teeth, the hinder- most of which is very prominent, being twice as long as those which precede it. Thranltes velox, of which in 1876 and 1881 Professor Carl Bovallius gave a detailed description, illustrated by numerous excellent figui-es, has since been found to belong to Stimpson's Bathynectes. The detailed description is in Swedish, the excellent figures are in a language which all but the blind can read with ease. The species has been identified with Stimpson's Bathijnectes longispina, 1871, but Canon Norman has recently made it probable that the priority rests with Portunus superbus, 0. G. .Costa, and that the name will, therefore, be BatJtynectes superbus, the species having ' a range apparently co-extensive with the North Atlantic,' A BATTLEDORE FRONT 71 and belonging to the British fauna as well as the Neapoli- tan in which it first was named. Another Mediterranean species, Portunus longipes, Risso, which is also found on British coasts, and which is figured and described by Bell in the ' British Stalk-eyed Crustacea,' p. 361, is now called Bathynectes longipes. Family 4>.-^-Podophthalmidce. The carapace is widest anteriorly, with the ' front ' very narrow, spatuliform, and inflexed. The orbits are extremely large, and the eye-stalks greatly elongated, occu- pying nearly the whole width of the carapace. Podophthalmus , Lamarck, 1801, contains but one recent species, the widely distributed Indo-Pacific Podoph- thalmus vigil, Fabricius. The long eye-stalks almost meet at their bases, and consequently the ' front ' is there almost linear, but it is prolonged for a short distance below and transversely dilated, so that, if straightened out, it might be compared to a battledore, or a broad-bladed knife, a spatula, whence the expression spatuliform has been applied to it. The great breadth of the short cara- pace, the very large denticulate chelipeds, and the unusual though not unparalleled length of the eye-stalks, make this a conspicuous and attractive species. According to Miers (1886) the only other genus that can claim a place in this family is Eupliylax, Stimpson, 1860, the name of which, meaning a good watchman, corresponds with the family character. Legion 2. Cyclinea. The carapace is more or less orbiculate. Acanthocyclus, Milne-Edwards and Lucas, 1843, has for its type species Acanthocyclus Gayi, which occurs com- monly 011 the shores of Chili and Patagonia, and in the Straits of Magellan. In this the eye-peduncles are short ; no longitudinal ridges are developed upon the endostome ; the ' front ' is rather narrow, with a prominent median lobe ; in the third maxillipeds the third joint is much longer than the small fourth one; the pleon of the male is narrow 72 A HISTOEY OF EECENT CEUSTACEA and five-jointed. Mr. Miers says, ' The nearest ally to Acanthocyclus is, I think, Bellia [Milne-Edwards, 1860], which resembles Acanthocyclus in the more or less orbicu- late carapace, in the form of the front, chelipedes, and ambulatory legs, but is distinguished by the narrower, more elongated merus [fourth joint] of the exterior maxil- lipedes, by the broader post-abdomen [pleon] of the male, and the less distinctly defined buccal cavity.' The legion Cyclinea, which cannot boast with certainty of more than a single genus and single species, may hope to have its ranks filled up in the course of time. At present it does not make a very good show, even on paper. Legion 3. Corystinea. The second antennas have elongate flagella. The third maxillipeds usually do not make a complete closure of the mouth-cavity and are extended over the anterior margin of its frame. The sternal plastron is narrow. The single family Corystidas does not require a separate defini- tion. It does not appear to contain more than eight genera, three of which are included in the fauna of Great Britain. Corystes, Latreille, 1803, has a very distinguishing charac- ter as compared with the forms previously discussed, in that the carapace is not transverse, but much longer than it is broad. Gorystes cassivelaunus (Pennant) has fre- quently attracted attention by the amusing resemblance of the carapace to a human countenance, which Herbst com- pares to the broad-nosed Kalmuck type. It is in Great Britain a convenient species for study, from the number of dead specimens that are often cast up on sandy shores. The sexes are easily distinguished. In the male the cheli- peds are enormously elongated, and the pleon is very small and has only five joints, although it is quite plain that the central one of the five is in reality a compound of three that have coalesced. In the female the pleon, though small, is broader than in the male, and has the seven joints distinct ; the openings of the vulvas can without difficulty be observed on the plastron between the third pair of legs ; ARTISTIC TOUCHES the chelipeds are of no unusual length. The very long- external antennae are a special feature of this crab. When. FIG. 3. Corystes cassivelaunus (Pennant), a female specimen, with the features on the carapace slightly accentuated. [Herbst.] the animal is burrowing in the sand according to its wont, the flagella of these antennae are brought close together, and the tips alone project from the funnel of the burrow. They are provided with stiff hairs on the inner margin, which no doubt assist in maintaining the funnel-opening of a due width. The joints of the peduncle can be strongly bent, and by this means, as Mr. Couch observed, the hairy fringes of the flagella can be made to brush one another 7i A HISTORY OF RECENT CRUSTACEA clown and clear away any clinging particles of sand. Mr. David Robertson had a female of this species alive in his possession for seven months, and, so far as his observation went, it would lie buried for weeks without seeking to change, the antennae clasping into each other to form the tube necessary for its breathing, by giving access to the water above. Through this tube he was also fortunate enough to see the ova sent up, and he infers that the animal at the proper time places them within the influence of the current which its breathing apparatus must con- stantly maintain. He notices that the pleon by its small size is less fitted to cover the ova than is generally the case among the Brachyura, but that this is compensated and accounted for by the burrowing habit. In a very young specimen, scarcely three tenths of an inch long, the ' front ' quite differs from what is seen in the adult, being produced into a conspicuous rostrum as in the genus Galathea, and the telson, instead of being rounded, is broadly emarginate. As two genera, Nautilo- corystes and Pseudocorystes, were so named by Milne- Edwards in 1837, to indicate their great resemblance ^ to the earlier genus Corystes, it may be interesting to point out some of the differences by which the three are dis- tinguished, and which in the early days of classification would probably have passed unnoticed. Corystes. The third maxillipeds have the fourth joint ' longer than the third, with the fifth joint inserted in a deep notch of its inner margin considerably below the apex. In the fifth pair of legs the seventh joint is narrow. Nautilocorystes. The third maxillipeds have the fourth joint a little shorter than the third, with the fifth joint attached at its apex. In the fifth pair of legs the seventh joint is widened. Pseudocorystes. The third maxillipeds have the fourth joint much shorter than the third, small, triangu- lar, with the fifth joint attached near the apex. In the fifth pair of legs. the seventh joint is widened. THE GENDERS OF GENERA 75 The species Pseudocorystes armatus, Milne-Edwards, was found at Valparaiso, and Milne-Edwards supposes that it may be the same as the ' Grass Crab,' figured by Browne in his ' History of Jamaica,' pi. 48, fig. 2. Atelecyclus, Leach, 1813, is a member of the family in which the third rnaxillipeds, contrary to the family custom, do make a complete closure of the mouth-cavity. The type species, Atelecyclus septemdeniatus (Montagu), was first observed on the south coast of Devon. Its carapace is nearly circular. Leach says that to the fishermen it is well known by the name of old man's face crab. The antero-lateral margin 011 each side is furnished with nine teeth, and probably for this reason Leach thought himself justified in changing the name to het&rodon, in which he has been followed by Bell. Montagu perhaps did not think that the point at each extremity of the series ought to be counted in, and at any rate no one can be injured by the retention of the name which it was his privilege as the discoverer of the species to choose. Thia, Leach, 1815, is represented both in the Mediter- ranean and in British waters, probably by one and the same species, called Thiapolita by Leach in 1815, in allu- sion to the polished surface of the carapace, but as there is no substantial reason for thinking it distinct from the species described and figured by Herbst as Cancer residuus in 1799, its name ought to be Thia residuus (Herbst), although some may prefer to call it Thia residua, not re- flecting that the animals are both male and female, and ignoring the old rule of Latin grammar that the mascu- line gender is to be preferred to the feminine. In this species, which like Corystes is a sand-burrower, the pleon is very narrow in both sexes, and, though in the male it is only five-jointed, the transverse grooves of the composite joint are so strongly marked, that all the seven joints might at first glance be thought to be distinct, as they are in the female. To conclude the discussion of the names used in this family, it may be mentioned, first, that although de Haan rightly claims priority for Dicera which he established 76 A HISTORY OF RECENT CRUSTACEA in 1833 over Nautilocorystes instituted by Milne-Edwards in 1837, yet Dicera must give way, having been already earlier used in other classes of zoology ; and secondly, that Oeidia, de Haan, 1833, a name meaning egg-like, must likewise be cancelled, having been found to be a synonym of Gomeza, Gray, 1831, a Corystid genus of the Japanese fauna. Legion 4. ThelpJmsinea. The carapace is more or less dilated at the branchial regions; the third maxillipeds have the fifth joint articu- lated at or near the front inner angle of the fourth or at its apex. The fingers of the walking legs are usually spinuliferous ; the verges of the male pass directly through the basal joint of the fifth pair. The species are fluviatile or live in damp forests. Family Thelplmsidce. This being the only family has the characters of the legion. Thelphusa, Latreille, 1819, contains numerous species, of which Mr. Miers observes that ' one, the com- mon Tlielpliiisa fluviatilis, occurs not only on the shores of the Mediterranean, but also in Asia Minor, Syria, and Persia ; the others are found in all the warmer temperate and tropical regions of the old world, extending southward to the Cape of Good Hope, Madagascar, and Australia, but not to New Zealand ; a species (TJtelphusa cliilensis) occurs in Chili.' Potamonautes, Macleay, and Geothelphusa, Stimpson, are so closely related to Thelphusa that their separation from it remains a matter of doubtful expedience. Krauss remarks that the Thelphusidas are especially fond of clear running streams in which they shelter them- selves under stones and plants. They are easily scared, and in spite of their monstrous chelipeds their long pe- raeopods carry them off at a great pace. The pearly Thelphusa (Thelphusa perlata, Milne-Edwards) has an earthy greenish colour, which matches its surroundings in the rivulets, whereas Thelphusa depressa, a species KIVER CEABS 77 which Krauss found at a waterfall in Natal, is yellowish and orange-coloured, in accordance with the cushions of moss among which it has its residence. Thelphusa dehaanii, White, occurs in the paddy fields of Japan, and has been taken at an elevation of 2,500 feet above the sea^ level. It has been already mentioned that the river crab of Europe is good eating. Milne-Edwards supposes that it was to this crustacean that Aristotle referred under the name Carcinus Heracleoticus. Paratelphusa, Milne-Edwards, 1855, was at first sup- posed to be a marine genus, but has since been proved to be an Indo- Malayan genus of fresh- water crabs, several species of which have been described by Mr. Wood-Mason. They differ from the rest of the Thelphusidae in having the distal end of the fourth joint of the chelipeds armed with a sharp spine, and are also said to have a greater general resemblance to some of the Candidas. Dr. de Man, in his elaborate Eeport on the Podoph- thalmous Crustacea of the Mergui Archipelago (' Journ. Linn. Soc.' 1887, 1888), includes the genus Thelpliusa in the next tribe, and the same arrangement is followed by Dr. Carnil Heller in his ' Crustacea of the Novara' 1865, the Thelphusinea being in fact intermediate in structure between the Candidas and the Gecarcinidae. 78 A HISTOKY OF EECENT CKUSTACEA CHAPTER VII TEIBE II. CATOMETOrA THE 'front' is bent downward. The carapace is broad anteriorly, often subquadrate, sometimes subglobose, trun- cate or arcuate forwards, but not rostrate. The epistome is short, often almost linear. The pairs of branchiae are usually fewer than nine in number ; the efferent channels open at the sides of the endostome. The third maxilli- peds have the fifth joint articulated at the front outer angle of the fourth, or less frequently at its apex, or very rarely at the front inner angle. The male verges are inserted either in the sternal plastron, or in the basal joints of the last pair of legs, thence passing through channels in the sternum beneath the pleon. The tribe contains four families, the Gecarcinidas, Ocypodidae, Grapsidas, and Pmnotheridge. The liver is said by Milne-Edwards to be in general central, extend- ing little or not at all over the branchial cavities. s Family 1. Gecarcinidce. The carapace is dorsally very convex, especially dilated over and in front of the branchial regions, with the antero- lateral margins usually entire and strongly arcuate. The ' front ' is of moderate width and strongly deflexed. The orbits and eye-stalks are of moderate size. The third maxillipeds have the fifth joint articulated at the front outer or near the front inner angle or at the apex of the fourth, which sometimes completely conceals it. The chelipeds in the adult male are powerful, usually unequal. The seventh joint in the walking legs is nearly always LAND CEABS 79 granulated and armed with longitudinal rows of spines. The pleon of the male usually covers the whole space between the bases of the last pair of walking legs. These land-crabs are called Toulouroux by the French. They inhabit the warm territories of both hemispheres. The third maxillipeds suffice without other details to dis- criminate the genera. Uca, Leach, 1817. The third maxillipeds have the fifth joint attached at the outer angle of the fourth ; the inner edges of the third and fourth joints are in one line ; along their outer edges the exopod is externally visible, and has a nagellum. Gecarcinucus, Milne-Edwards, 1842. The third maxilli- peds have the fifth joint attached to the middle of the apical margin of the fourth ; the inner edges of the third and fourth joints are in one line ; the exopod as in Uca. Cardisoma, Latreille, 1825. The third maxillipeds have the fifth joint attached at the outer angle of the fourth ; the inner edges of the third and fourth joints form a re-entering angle ; the exopod as in. Uca. Gecarcoidea, Milne-Edwards, 1837. The third maxil- lipeds have the fifth joint inserted in a deep groove of the apex of the fourth ; the inner edges of the third and fourth form a re-entering angle ; the exopod is without flagellum and concealed beneath the third joint. Gecarcinus, Leach, 1815. The third maxillipeds have the fifth joint attached on the inner margin of the fourth and completely concealed by it ; the inner edges of the third and fourth joints form a re- entering angle ; the exopod as in Gecarcoidea. Hylceocarcinus, Wood-Mason, 1874. The third max- illipeds have the fifth joint attached to the middle of the apex of the fourth ; the inner edges of the third and fourth form a re-entering angle ; the exopod as in Gecarcoidea. 80 A HISTORY OF RECENT CRUSTACEA In the last four genera it will be perceived that the maxillipeds do not form a completeoperculum,but by the arrangement of the inner edges of their third and fourth joints they leave a lozenge-shaped space over the mouth- opening uncovered, while in Uca and Gecarcinucus the straight inner edges from either side can be brought exactly together so as to close the cavity completely. Mr. Wood- Mason points out that the character of the exopod distin- guishes Gecarcinus, Gecarcoidea (which he calls Pelocar- cimts), and Hi/lceocarcinus from the three preceding genera, and that they are distinguished from one another by a further character of the maxillipeds, for in Gecarcinus the three terminal joints are completely hidden, in Hylceocar- cinus they are partially visible, and in Gecarcoidea com- pletely so. None of the Crustacea have more attracted the atten- tion and excited the wonder of travellers than some of those belonging to this group. Like the twin snakes that came over the sea and deliberately landed at Troy to slay Laocoon and his two sons, these crabs have, contrary to nature, forsaken the ample waters of the ocean, scorned all the brooks and rivers and lakes, and carried out a portentous invasion of the dry land. Still they are by no means indifferent to moisture. The vaulted part of the carapace over the branchial regions is lined with a very spongy membrane, and sometimes a fold of the membrane along the lower edge of the cavity forms a kind of tube in which water may be held as in a reservoir. But their form and structure are not so surprising as their manners and customs. Under the heading Cancer ruricola, a species of Geccw- cinus, Herbst brings together many curious particulars, depending largely upon Patrick Browne's ' History of Jamaica.' In the Bahamas, he says, and in tropical regions these land-crabs are so numerous that when they creep out of their holes the ground seems to be in motion. One little island is so full of them that it has been called Crab Island. They are just as frequent in certain districts of Jamaica and in some of the Caribbee islands. The same REMARKABLE BEHAVIOUR 81 was the case at St. Croix, but since the cutting clown of the forests and destruction of thousands of the crabs, their number has diminished. They generally take up their abode on the hills, not less than one mile nor more than three miles from the coast. It" is in the morning and evening that they are to be found in greatest numbers under the trees. Go away then without a stick in hand, and they will approach with uplifted claws as if threatening an assault. But if they are themselves assailed with a stick or a switch, they retreat, yet still facing the foe, and ever and anon clashing their claws together to strike terror into him. Thus they withdraw to their holes in the rock or the rotten tree or deep burrows in the ground. They are capital eating, and are one of the principal food resources of the natives, who improve the flavour by fattening them up for three or four days in a potato field. But a warning is given that they do not always suit the stomach of Euro- peans, since they are apt to produce cold hypochondriac humours, whereby some explain the slow melancholy nature of the Caribbee islanders. When seized by a leg or a claw these crabs relinquish it so readily as to produce the im- pression that their limbs are only stuck on. The lost appendage would be renewed at the next change of skin, but it often happens that the sacrifice which has saved the crab from its human foes exposes it as a defenceless victim to those of its own race. The pairing season is said to be in March and April. In May, the rainy period, they march in great hosts towards the sea, to bathe and lay their eggs in it. ' Then all roads and brooks are filled with them, and it is indeed a very wonderful instinct, which the Creator has given them, to go direct to that part of the island where there are stretches of sand and slopes from which they can most easily arrive at the sea. Nothing can hinder them from going the straight road towards the sea, for they go over everything that comes in their way, be it hedges, houses, churches, hills or cliffs, straight over everything they go, and rather clamber up at the peril of their lives, than make a circuit. In the night, for example, they will creep in at a window, and G 82 A HISTORY OF RECENT CRUSTACEA come on to the beds, causing the unwary occupants no small alarm by their clatter. If one has the misfortune to tumble down and damage its limbs, it is immediately eaten up by the rest. It must be a wonderful sight, to see them come down the hills. Everywhere they issue from hollow trees, rotten stems, from under the rocks, and out of innumerable holes. The fields are so covered with them, that unless they are chivied away, there is no setting foot to ground without treading upon them. What with the infinite variety of their markings, their brilliant colours, their sideways gait, their celerity, I know of scarcely any sight comparable with this one. Unless the description of their march has been embellished by the force of imagination, the journey is conducted with as much order as if they had a very experienced commander.' The vanguard, consisting of none but males, starts some days in advance. Then follows the main army, composed chiefly of females, their battalions often covering a space of a mile and a half long by forty or fifty paces broad, and covering it so closely as almost to hide the ground. Some days after, the rear-guard, containing both males and females, closes the vast procession. Sometimes all the divisions are brought to a halt several days by the want of rain, a want which makes prolonged land-travel impossible to a crustacean. But when Herbst says that these hosts follow the line of the rivers and water- courses, the statement, though highly probable in itself, is scarcely consistent with the miraculous bee-line which he had previously described. If anyone approaches the army and puts it into alarm, these martial crabs draw back facing him, with their claws uplifted and open to be constantly ready for defence. The nip of one of them, it is said, can tear out a piece of flesh, and the claw, even after it has been thrown off by its owner, will continue for a minute to pinch with incredible force. The noise of their march is compared to the rattling of the armour of a regiment of Cuirassiers. Having arrived on the coast, they bathe once in the sea, and then creep into some shelter to rest. The females enter the sea a second time and there deposit their SEASIDE LODGINGS 83 eggs. These are cast up by the waves upon the sand, and in due course out creep the young crabs, which then cling to the rocks in thousands, but presently quit the water for any suitable places of protection on land, there acquiring strength to follow their mothers up the country. : Patrick Browne says : i The eggs are discharged from the body through two small round holes situated at the sides, and about the middle of the under shell ; these are only large enough to admit one at a time, and, as they pass, they are entangled in the branched capillaments, with which the outer side of the apron is copiously supplied, to which they stick by means of their proper gluten, until the creatures reach the surf, where they wash 'em all off, and then they begin to return back again to the mountains. It is re- markable that the bag or stomach of this creature changes its juices with the state of the body; and, while poor, is full of a black, bitter, disagreeable fluid , which diminishes as it fattens, and, at length, acquires a delicate rich flavour. About the month of July or August the crabs fatten again, and prepare for mouldering, filling up their burrow with dry grass, leaves, and abundance of other materials ; when the proper period comes, each retires to his hole, shuts up the passage, and remains quite inactive, until he gets rid of his old shell, and is fully provided with a new one. How long they continue in this state is un- certain, but the shell is first observed to burst both at the back and sides, to give a passage to the body, and it ex- tracts its limbs from all the other parts gradually after- ward. At this time the fish is in the richest state, and covered only by a tender membranous skin variegated with a multitude of reddish veins, but this hardens gradually after, and becomes soon a perfect shell like the former ; it is, however, remarkable that during this change there are some stony concretions always found in the bag, which waste and dissolve gradually, as the creature forms and perfects its new crust. A wonderful mechanism ! ' A footnote remarks that the concretions, which are the well- known gastroliths or crab's eyes, ' are seldom under two or more than four.' o 2 84 A HISTORY OF EECENT CRUSTACEA Since it is during this period of ' mouldering ' that the crabs are fattest and best flavoured, Herbst finds it easy to suppose that greedy man will not leave them safe in their repose. On the contrary, he busily digs them out with a spade. Considering how readily under some cir- cumstances these crustaceans shed their limbs, it is singu- lar that in exuviation they are able to cast off their whole caparison so uninjured and complete that it might be mis- taken for the living animal. Careful inspection is required to perceive near the insertions of the limbs the ventral slit through which the animal has made its escape. It was in a West Indian species of Gecarcinus that Professor Westwood observed that the young issued from the egg in a form not materially different from that of their parents. This experience, combined with Rathke's similar observation in regard to the European crayfish, led him at first to throw doubt upon Vaughan Thompson's theory of crustacean metamorphoses. But it was soon brought to light that the examples of the land-crab and the freshwater crayfish were interesting exceptions to a still more interesting rule, and there are few who would now deny that these exceptions are to be explained as modifications in the life-history of the animals concerned, i7 acquired late in the course of time to suit the new condi- tions of existence encountered by creatures emerging from the sea to a life in fresh water or on dry ground. That no crustaceans have been able to cut themselves loose from some dependence upon moisture is not very wonderful, since in that respect man himself is still an aquatic animal. Gecarcinus lagostoma, Milne-Edwards, represented on Plate II, is a widely distributed species. Hi/lceocarcinus Humei, Wood-Mason, occurs in ' the dark dense damp forests of the Nicobar Islands.' Uca una (Linn.), the crab of the mangrove swamps of Brazil, may be mentioned as a rare instance of one that has been allowed to possess the names by which it was figured and described centuries ago. In this genus the last joints of the walking legs are compressed and un- PI. ii. i Cecarcmus laqostoma Platyonichus indescens C depressa Cfielipcd australiensis EACEES 85 armed. M. Jobert, in examining the breathing apparatus of land-crabs, has found that of Uca una to be the most complete. There is a regular movement of inspiration and exspiratioii to keep the air from stagnating in the breathing chamber, and between the third and fourth and the fourth and fifth limbs there are small supplemental inspiratory orifices coated externally with long hairs (see Sp. Bate, ' Brit. Assoc. Report,' 1880). Family 2 . Ocypodu Ice. The carapace is in general moderately convex, cancroid or trapezoidal, with the antero-lateral margins straight or arcuate, the branchial regions not greatly dilated. The ' front ' is of moderate width or very narrow. The orbits and eye-stalks are of moderate size or greatly developed. The third maxillipeds have the fifth joint articulated at the front inner or rarely at the front outer angle. The chelipeds in the adult males are in general of moderate size, sometimes slender and elongate. The seventh joint in the walking legs is stiliform, without strong spines. The pleon does not always cover the whole width of the sternum between the last pair of legs. The species are generally small, littoral, or inhabitants of shallow water, but are not unknown from considerable depths. There are nearly forty genera assigned to the various subdivisions of this family. Ocypode, Fabricius, 1798, has the orbits very large and open, extending all along the anterior margin on either side of the narrow and deflexed ' front.' The eye-stalks are large, with a short basal joint, the terminal part often prolonged distal ly as a spine or tubercle, the large corneas covering much of the lower surface of this terminal joint. The chelipeds in the adult male are unequal and well de- veloped, and usually the palm has a vertical series of short raised lines or tubercles on the inner surface, which form a stridulating ridge. As the name swift-of-foot implies, these Crustacea are especially noted for their rapidity of movement. They arc just the opposite of some of the strong-armed, thick- 86 A HISTORY OF RECENT CRUSTACEA shelled, slow-moving 1 Cancridae. On wind-swept stretches of sandy beach, and coloured like the sand, they some- times seem rather to be borne on the wings of the wind than to run. Also with their compressed lancet-like lingers they are extremely dexterous in digging into the sand. They burrow holes an ell deep, generally perpen- dicular, and from these they wander far, when the tide is out, in search of food. Krauss observed in South Africa the species Ocypode ceratoplitlialmns (Pallas), and others, and he says that while they are busy hunting, every now and then they look carefully round, raising their stalked- eyes upright, and standing on. tiptoe. At the slightest movement towards them they run with uncommon rapidity to the nearest hole, or, if the danger is too close, press themselves flat on the sand, till an attempt is made to seize them, and then off they dart. In running they carry their bodies high, doubling and dodging with such speed and cunning that it is a difficult matter to lay hold of them. When the tide comes up, they are enclosed in their flooded burrows, and as soon as the waves retreat, they are busily employed in clearing them, "shovelling out the wet sand and heaping it at some little distance off. The American species, Ocypode arenaria (Catesby), is de- scribed by Professor S. I. Smith as having precisely similar habits. According to his observation it lives largely upon the Amphipods of the genus Talorchestia, known as ' beach-fleas,' which inhabit the same localities. 'It will lie in wait,' he says, ' and suddenly spring upon them, very much as a cat catches mice. It also feeds upon dead fishes and other animals that are thrown on the shore bv the */ waves.' It is of this species, under the synonym of Ocijpoda r/wmbea, Fabricius, that Fritz Miiller speaks in his memor- able work ' For Darwin.' ' In the swift-footed Sand-crabs (Ocypoda),' he says, ' which are exclusively land animals, that can scarcely live in water for a single day, and which in far less time than that are reduced to a state of com- plete collapse in which all voluntary movements cease- there has long been known a peculiar arrangement con- CROSS-EXAMINING A CRAB 87 nected with the third and fourth pairs of legs, but that these had anything to do with the branchial cavity was not suspected. These two pairs are pressed more closely together than the rest. The opposed surfaces of their basal joints, that is, the hinder surface in the third, and the front surface in the fourth pair, are flat and smooth, and their margins are clos jly fringed with long, sheeny, peculiarly formed hairs. Milne-Edwards, who compares them to articular surfaces, as their appearance warrants, thinks that they serve to diminish the friction between the two legs. On this supposition the question arises why precisely in these crabs and only between these two pairs of legs such a provision for diminishing friction is neces- sary, not to mention that it leaves unexplained the singular hairs, which must augment instead of diminishing friction. While, then, I was bending to and fro in ever so many directions the legs of a large Sand-crab, in order to see in what movements of the animal friction occurred at the place in question, and whether perhaps these were move- ments often recurring and of special importance to it, I observed, when I had stretched the legs far apart, a round opening of considerable size between their bases, through which air could easily be blown into the branchial cavity or even a slender probe be introduced. The aperture opens into the branchial cavity behind a conical tubercle, which stands above the third foot at the place of a bran- chia which is wanting in Ocypoda. It is laterally bounded by ridges which rise above the articulation of the legs and to which the lower edge of the carapace is applied. Also outwardly it is overarched by these ridges with the ex- ception of a narrow slit. Over this slit extends the cara- pace, which just at this point projects further downwards than elsewhere, and so a complete tube is formed. While Grapsus always admits water to its branchiae only from in front, in Ocypoda I saw it also streaming in through the just described aperture.' For its details about one particular crustacean such a passage is interesting, but it is far more important as a lesson in scientific observation. There are numbers of A HISTORY OF RECENT CRUSTACEA persons who might be familiar with the smooth flat sur- faces opposed to one another in the legs of a crab, and who yet would never make the guess that it was an arrangement to diminish friction. With the guess made for them by some one else they would be contented for another lifetime, and so on perhaps with the objection to the guess that if friction was to be avoided, the legs would not have been fringed with hairs. Fritz Miiller was well aware of the old principle that Nature makes nothing in vain, and was pretty confident to begin with that there would not at the same point be two arrangements counter- acting one another, the one increasing and the other diminishing friction. The smooth surfaces of the limbs enable them to act as tight-closing lips to the breathing- aperture which he discovered at their bases. As to the fringing hairs Fritz Miiller hazards the conjecture that they may be olfactory. This might seem a very extra- vagant supposition, that a crab should have the equiva- lent of a nose attached to its legs, did we not remember that some crustaceans have organs of hearing in the appen- dages of the tail. Moreover, Fritz Miiller observed that in his Ocypode the olfactory filaments in their usual place on the antennae were much reduced, and that the flagella of the antennae never make the peculiar beating move- ments familiar in other crabs, and he argues that in an air-breathing crab, just as in the air-breathing vertebrates, the sense of smell might be expected to have its organ at the entrance of the breathing cavity. Gelaslmus, Latreille, 181 8, meaning the laughable crab, is a genus containing a large number of species that haunt warm climates. Here, too, the orbits and eye-stalks are long. The pleon in the male is narrow and distinctly seven-jointed, and its base does not occupy the whole width of the sternum between the walking legs. But the most striking feature is the disproportionate size which in the male is attained by either the right or the left cheliped. According to de Haan his species Gelasimus arcu/i<* is called in Japanese Siho maneki, which means ' beckon- THE CALLING CRAB 89 ing for the return of the tide,' because, when the creature is left on the dry shore, by the movement of its claws it seems to be appealing to the waves to come back again. The specific title of Gelasimus vocans (Linn.), and the trivial Fig- 4. Gelasimus arcuatus, de Haan, a male specimen, and pleon of the male detached. [DeHaan.] name, the calling crab, refer to the like action. Of the customs of an American species the following account is given by Professors Verrill and S. I. Smith : ' On sandy beaches near high-water mark, especially where the sand is rather compact and somewhat sheltered, one of the "fiddler-crabs," Gelasimus pugilator [Latreille], 90 A HISTORY OF RECENT CRUSTACEA is frequently found in great numbers, either running actively about over the sand, or peering cautiously from their holes, which are often thickly scattered over con- siderable areas. These holes are mostly from half an inch to an inch in diameter, and a foot or more in depth, the upper part nearly perpendicular, becoming horizontal below, with a chamber at the end. Mr. Smith, by lying perfectly still for some time on the sand, succeeded in witnessing their mode of digging. In doing this they dug up pellets of moist sand, which they carry under the three anterior ambulatory legs that are on the rear side, climb- ing out of their burrows by means of the legs of the side in front, aided by the posterior leg of the other side. After arriving at the mouth of their burrows and taking a cautious survey of the landscape, they run quickly to the distance often of four or five feet from the burrow before dropping their load, using the same legs as before and carrying the dirt in the same manner. They then take another careful survey of the surroundings, run nimbly back to the hole, and after again turning their pedunculated eyes in every direction, suddenly disappear, soon to reappear with another load. They work in this way both in the night and in the brio-litest sunshine, whenever the tide is O o / out and the weather is suitable. In coming out or going into their burrows either side may go in advance, but the male more commonly comes out with the large claw for- ward. According to Mr. Smith's observations this species is a vegetarian, feeding upon the minute algas which grow upon the moist sand. In feeding, the males use only the small claw with which they pick up the bits of algas very daintily ; the females use indifferently either of their small claws for this purpose. They always swallow more or less sand with their food. Mr. Smith also saw these crabs engaged in scraping up the surface of the sand where covered with their favourite algas, which they formed into pellets and carried into their holes, in the same way that they bring sand out, doubtless stowing it until needed for food, for he often found large quantities stored in the terminal chamber.' AKCHITECTURAL EFFORT 91 Aii earlier observer, Bosc, who studied this same species in Carolina, declares that these crabs were to be seen in thousands and even in millions on the margin of the sea or of tidal rivers. He remarks that, if a man or any animal comes among them, they lift up the large claw, and holding it forward, as if challenging their opponent to fight, in that attitude they scurry off sideways. They have, he says, a great number of enemies among the otters, bears, birds, turtles, alligators, and the like, but they are so prolific that the devastation made among them by these foes is imperceptible. He occasionally saw the ' calling- crabs ' swarming over a carcase on the shore and disputing with the vultures for strips of the carrion. He was very anxious to see them make their burrows, but they never would work in his presence, doubtless not from shyness, but from some prudential motive. Gelasimus minax, Leconte, the largest of the American ' fiddler-crabs,' lives in salt marshes or fresh water. Over the mouth of its burrow Mr. T. M. Prudden ascertained that this crab often constructs a regular ovenlike arch of mud, and that it sits in this doorway on the look out for whatever may befall. Professor Smith kept a large male of this species in a glass jar containing nothing but a little siliceous sand, moistened with pure fresh water, for over six months. It was for ever pacing round the jar and trying to climb out, was never observed to rest or show fatigue, ' and after months of confinement and starvation was just as pugnacious as ever.' The species Gelasimus arcuatus, de Haan, already mentioned, was observed by Krauss in South Africa as occupying muddy ground, and having a bluish-grey colour suitable to its residence. The appropriateness of the generic name will be appreciated in the light of his in- cidental remark that ' it is truly comical to see these crabs with uplifted arms in countless numbers scampering over the dark mud.' Gonoplax (originally spelt Gone-plat and Goneplax), Leach, 1814, is a North-Atlantic and European genus, which till lately contained only one species, Gonoplax 92 A HISTORY OF RECENT CRUSTACEA rhomboides (Linn.), called in Bell's ' History of the British Crustacea' Gonoplax mjiiluta (Fabricius), the angular crab, the specific name obviously, and the generic name probably, alluding to the angular character of the carapace. A second species, closely resembling the first, and named Gonoplax sinuatifrons, Miers, was obtained by the Challenger at Amboina. The elongated orbits and eye-stalks cannot fail to attract attention, and the latter especially when they ai-e suddenly erected from a position of rest within the former. The male has the chelipeds of a remarkable length, and these, at least when in confine- ment, he is fond of clashing together in a noisy and perhaps threatening manner. The joints of these limbs are so proportioned that while they are able to seize food at a great distance, they can also convey it to the mouth. The pleon is seven-jointed in both sexes. OmmatocarclnuSj White, 1852, is distinguished from its near neighbour Gonoplax by a still narrower ' front,' a great development of the antero-lateral spine on each side of the carapace, and still more elongate eye-stalks, to which reference is made in the generic name, meaning ' the crab with the eyes.' There is but one species, Omma- tocarcinus Macgillivrayi, White. This is found in Austra- lian and New Zealand waters. MacropJithalmus, Latreille, 1829, with a name mean- ing ' long-eye,' surpasses the two preceding genera in the length of the orbits, and the eye-stalks are exorbitant in the literal sense in certain species, in which they are pro- longed laterally beyond the orbit's outer angle. The species are numerous, occurring ' in the littoral or shallow waters of all parts of the Indo-Pacific region.' In some of the species, as also in the genera Hellce, de Haan, 1835, and Metaplax, Milne-Edwards, 1852, the males have on the arms of the chelipeds a short horny ridge, which Dr. de Man calls ' the musical crest,' on the supposition that the crab produces musical sounds by rubbing this crest against a row of granules below the orbit. Naturally this crab-music must only be judged by a crustacean standard. THE GRAPSID^: 93 A certain amount of uniformity, especially as regards the flatness of the carapace, may be inferred to exist in this family from the number of genera with names all alike ending in -plax, as Acanthoplax, Hyoplax, Hemiplax, Ca-mp- toplax, Bathyplax, with many others. The genus Gerj/on, Kroyer, 1837, may claim a passing notice as one of those instances in which systematic arrangement finds itself at fault. It is sometimes placed among the Cyclometopa and sometimes among the Cato- metopa. Mr. Miers says that it is very nearly allied to Pseudorhombila and Pilumnoplax in the latter, and to Galene in the former group. That, on the theory of the evolution of different groups from a common stem, such inosculant forms are almost sure to occur, has long been recognised. Darwin himself humorously admits that while as a theorist he delighted in coming across them, as a naturalist engaged in classification he found them an un- o o mitigated nuisance. Family 3 . Graps idoe . i The carapace is depressed or moderately convex, more or less quadrilateral, with the lateral margins straight or slightly arcuate. The 'front' is never very narrow, in general decidedly broad. The orbits and eye-stalks are of moderate size. The third maxillipeds have the fifth joint articulated at the apex or the front outer angle of the fourth. The chelipeds in the adult male are usually subequal, moderately developed. In the walking legs the seventh joint is stiliform, compressed, and either smooth or spiniferous. The pleon at the base usually covers the whole width of the sternum between the last pair of legs. The species are almost always littoral or shallow-water forms, with a rare exception in deep water. In this family there are about twenty-four genera Grapsus, Lamarck, 1801, is a wide-ranging genus which was brought to the notice of Europeans a century and a half ago in the species Grapsus maculatus (Catesby. 1743 and 1771), to which Bosc in 1802 applied the better A HISTORY OF RECENT CRUSTACEA known name of Grapsus pidus. Professor Tli. Barrois, in his account of the Crustacea of the Azores, speaks of this and two companion species as running with astonishing velocity among the rocks near the sea. The brilliantly coloured Grapsus, with its limbs of a marvellous red, he calls a superb species. As it occupies by preference the sides of the perpendicular cliffs, it is easy to believe the statement that prodigies of agility and cunning are re- quired for capturing uninjured specimens. In Charleston Bay Bosc had a much easier task. There he noticed that these crabs almost always kept themselves concealed under stones or pieces of wood, and, as these objects are rare in that locality, every day on the retreat of the tide he was sure to find fresh specimens of Grapsus under the hiding-places from which he had taken other specimens on the previous day. Darwin, in ' A Naturalist's Voyage,' when speaking of the nests of the tern at St. Paul's Rocks in the Atlantic, says, ' It was amusing to watch how quickly a large and active crab (Grapsus), which inhabits the crevices of the rock, stole the fish from the side of the nest, as soon as we had disturbed the parent birds. Sir W. Symonds, one of the few persons who have landed here, informs me that he saw the crabs dragging even the young birds out of their nests and devouring them.' The voracity and audacity, the cunning and speed and jumping powers of these crabs of St. Paul's Rocks are amusingly described in the ' Log Letters of the Challenger,' by Lord George Campbell, who, however, saw no proof that they ate the young birds. About a dozen other genera have been formed with names in which Grapsus is part of the compound, as Geocjrapsus, Paragrapsus, Plati/grapsus, and the like. Several of these contain species which were at one time included in the genus Grapsus, and which are by no means very remote from it. The Cancer marmoratus of Fabricius has been trans- ferred from Grapsus to Pachygrapsus, Randall, by Stimpson, and to Goniograpsus, Dana, by Miers. It is a European species, common among chinks of the rocks in the Adriatic. It prowls about on the shore by night to feed on dead PI. iii. Eriocheir japonicus, de Haan. THE GULF-WEED CKAB 95 animals cast up by the waves. It is said to be timid, running off with great speed if scared, but if stopped it shows temper and nips hard. It is also very common, according to Lucas, in Algeria, where it is eaten by the poor. Fine specimens for a naturalist's collection are not easy to catch because of their extreme readiness 011 the least alarm to ensconce themselves deep in rifts of the rock. If in their headlong haste they sometimes slip into a hole too shallow to contain them, entirely, the pursuer will still be likely only to obtain their cast-off legs, since they readily relinquish them all rather than be captured. Nautilograpsus, Milne-Edwards, 1837, like some of the genera previously described, has third maxillipeds which do not form a complete operculmn. In 1825, in Bowdich's ' Excursion to Madeira and Porto Santo,' Leach gave to this genus the name Planes, a wanderer, but from want of a sufficient accompanying description this has been re- garded as technically only a manuscript name, not entitled to priority. It may, however, be doubted whether this is a right decision, since a figure of the type species, Planes minutus (Linn.), was appended, and there appears to be but a single species in the genus. The name of wanderer is very appropriate, since this, the common Gulf-weed Crab, is said to occur nearly everywhere on floating weed in the temperate and tropical seas of the globe. If, as is probable, it was the presence of this little crab on the Sargassum bacciferum that Columbus adduced as an argu- ment to prove to his despairing sailors the proximity of land, it was not quite so much to the point as the sailors appear to have thought it. Columbus himself had other and more satisfactory reasons for his own confidence. Patrick Browne calls it the Turtle-Crab, remarking, ' I found this insect on the back of a turtle, near the western islands.' Eriocheir, de Haan, 1835, meaning 'woolly-hand,' contains a species, Eriocheir ja/ponicus, of very singular appearance, the great claws looking as if they were muffled up in cuffs of long fur. It is represented in the accom- panying plate, which is reduced from de Haan's work. 90 A HISTORY OF EECENT CRUSTACEA The detached figures show the chelae of the young male and the female, and the pleoii respectively of male and female. By the Japanese this species is called the moun- tain savage or the hairy crab. It occupies brackish waters, passing from them into fresh-water streams, by means of which it ascends the mountains, where it is often observed on dry land. Varuna, Milne-Edwards, 1830, has the single species Varuna litterata (Fabricius), common in the Indo-Pacific region, and attracting attention by the marking on the carapace to which the specific name refers. The capital letter H is here considered to be formed with more than usual distinctness by the longitudinal grooves that sepa- rate the lateral from the median regions, and the trans- verse groove which appears to form the upper boundary of the cardiac region. Sesarma, Say, 1818, includes a large number of species found in the shallow waters of all the warm regions of the globe. In this genus the ' front ' is broad ; the third maxillipeds, when closed, still leave open a lozenge-shaped space, and have the large fourth joint traversed by a ridge from the front inner angle to the outer angle behind ; the O O ' pterygostomian regions have a granular or reticulated sur- face, which in general is divided into little squares of extreme regularity. Reference has been already made to Fritz Miiller's in- vestigation of the breathing arrangements in land-crabs. He was anxious to put the theory of evolution to a test. The resemblances which prevail among all crabs point, on that theory, to their derivation from a common ancestral form, but the differences which prevail in the numerous genera of land-crabs point to a divergence that must have begun long before they assumed terrestrial habits. That, at least, is what Fritz Miiller assumes, and few evolution- ists will be inclined to deny it. If, then, several different forms of water-breathers at various times and places have independently developed into air-breathers, it is unlikely that the necessary changes will all be of the same pattern, [t is so unlikely that, had it proved to be the case, Fritz DARWIN'S THEORY TESTED 97 Miiller was prepared to regard it as a very damaging blow to the theory of evolution. The result was just the oppo- site, as will be seen by a comparison of his observations on several species and genera. Those on Ocypode have been already quoted. In the family Grapsidae he describes, under the name Aratus Pisonii, the species which Milne-Edwards calls Sesarma Pisonii, a sweet little vivacious crab, which climbs the mangrove-bushes and feeds upon their leaves. Its short sharp claws are well fitted for climbing, but they prick like pins when the creature runs over a bare hand. Once, when he had one of these seated on his hand, Fritz Miiller noticed that it raised up the hinder part of its c'arapace, and that by this means a wide slit was opened upon each side over the last pair of feet, affording a view into the bran- chial cavity. When studying this phenomenon in another species, which he took to be a true Grapsus, he observed that with the formation of the slit behind, the anterior part of the carapace seems to sink so as partly or entirely to close the anterior afferent opening. As the lifting* of the carapace never takes place under water, he infers that the animal opens its branchial cavity in front or behind accord- ing as it requires to breathe water or air. He had noticed the elevation of the carapace, also, in species of Sesarma and Cyclograpsus, which burrow deep in swampy ground, and often scamper about on the wet mud, or sit watch- fully before their burrows. But to observe the action in these is a work of patience, since they can continue to breathe water long after they have quitted the source of supply. That reticulation of the shell between the afferent and efferent branchial orifices, which has been mentioned in the character of the genus Sesarma, has a special purpose. The squared meshes of network are due partly to fine tuberculation and partly to curious geniculate hairs form- ing over the surface a sort of fine hair-sieve. When the water issues from the branchial cavity it spread^ through this network, and can take up fresh oxygen, whereuporj the appendages ot the third niaxillipeds, working in the H 98 A HISTOKY OF KECENT CRUSTACEA afferent opening on either side, by their powerful move- ments bring it back to the branchial cavity. The two ridges on the maxillipeds, which are often densely fringed with hairs, meet in front and form a triangular break- water which prevents the streams intended for the bran- chife from entering the mouth-opening. Of the rock-haunting species of the genera Plagusia, Latreille, 1806, and Goniopsis, de Haan, 1835, Krauss speaks with a sort of admiration. At low tide they come bustling out of their crannies in hosts. By help of their soft elastic bodies, and their limbs cut out for the very purpose, they clamber over rough blocks and steep sides of rock, jump from one crag to another, and creep into the most inaccessible crevices. They are not very swift, but very canny, so that on their own ground, in spite of their multitude, it is almost impossible to catch any of them. In the fear of pursuit they will let themselves drop several feet from one ledge on to another, or plunge a fathom down into the sea and paddle off to the nearest rock. Acanthopus clavimdmis, de Haan, is a tiny species nearly allied to Plagusia, but with different habits. It lurks under stones, and it may seem a light matter to turn over a stone and catch it, but before the stone is well over the crab will have whisked to the other side, and when at length it has been pinned fast, it is no easy task to drag- away its thin body and clinging talon-like claws without breaking them. The name of this genus having been pre- occupied, it has been changed by Miers to Leiolophits. Plagusia contains species that come from the Atlantic and Pacific, and some of these have been taken in the Medi- terranean under circumstances worthv of note. In the \j winter of 1873 an iron vessel entered the port of Mar- seilles. It had come from Pondichery, by way of the Cape of Good Hope, having had a long and stormy voyage in the most rigorous season of the year. To the iron plates of this ship had become attached a little forest of algas and barnacles ; and living among these were a number of higher Crustacea of exotic origin. Two of the specimens were found by Professor Catta to belong to a new species FRIEND OE FOE 99 which in 1876 he named Pachygrapsus adrtna; one was a Nautttograpsus (or Planes) minutus, a species scarcely ever found in the Mediterranean ; the remainder belonged to two species, which M. Catta speaks of as Plagusia squa- mosa and Plagusia tome?itosa. The latter, a South African species, should rather, it seems, be designated Plagusia c/iabrus (Linn.), and the former Plagusia depressa (Fa- bricius). It was this last-mentioned one that was the most numerous, being present in hundreds. As an Atlantic species, it might not have had far to come. The point of special interest, however, lies, as Catta explains, in showing the effects on distribution that may be produced by unconscious human agency. Family 4. Pinnotheridce. The carapace is usually more or less menibranaceous, convex or depressed, with the antero-lateral margins entire or very slightly dentate. The 'front,' orbits, and eye- stalks are very small. The buccal frame is usually arcuate anteriorly. The third maxillipeds have the fourth joint well developed, and usually the third also, the fifth articu- lated at the apex, or at the front inner angle, or more rarely the front outer angle, of the fourth. The chelipeds in the adult male are small or moderately developed. The walking legs are slender and generally naked, with the seventh joint stiliform, unarmed. The pleon of the male in general does not cover the whole width of the sternum between the last pair of legs. The crabs of this family are small, and many of them live in the shells of bivalve molluscs, tests of Echini, tubes of annelids, and other borrowed habitations. Miers dis- tributes five-and-twenty genera over four sub-families. Pinnotheres, Latreille (in Bosc), 1802, was known to the ancients under the same name, but more commonly under the name Pinnoteres. It is a great pity that Latreille did not adopt the latter, which is in all pro- bability the older form. Small as the difference in sound, the difference in sense is considerable. Pinnotheres means H 2 100 A HISTORY OF RECENT CRUSTACEA one that hunts the Pinna, and, in accordance with this designation of the genus, Oppian tells the story that when oysters open their valves to take in the mud and water OH which they live, one of these crafty little crabs picks up a pebble and thrusts it in, so that the oyster is prevented from closing its shell again, and the crab enters and feeds O O upon its nutritious flesh. Gesner in the sixteenth century expressed his confidence that this was mythical, since you never find any bites upon the mussels, pectens, pinnas, and oysters that are attended by these crabs. The name Pinnoteres means one that watches or guards O tiio Pinna, and there can be little doubt that it was the form used by Aristotle, seeing that he also speaks of it as Pinnophylax, a word of precisely the same meaning. Not only Aristotle, but many succeeding writers of renown, such as Cicero, Pliny, and seemingly Linnasus himself, accepted the opinion that there was a compact between the mollusc and the crustacean for their mutual benefit. Whenever little fishes swam in between the expanded valves of the mollusc, it was supposed that its companion gave it a little friendly nip, upon which the valves snapped together, the prey was secured, and shared between the confederates. A similar policy was pursued to exclude the intrusion of a dangerous foe. The great antiquity of the belief is at- tested by the fact that the Egyptians in their hieroglyphics made use of the pinna and crab to symbolise the helpless- ness of a man without friends. That the belief was un- tenable was pointed out by many naturalists from Gesner down to Cuvier, on the ground that molluscs do not feed on little fishes, and that the residence of the crabs within the valves was sufficiently explained by the prevailing softness of the carapace in this family. This indeed ap- plies chiefly to the females, and it is the females that a]) pear to be most frequently found thus domiciled. . It is so much the nature of crustaceans to take refuge in any sort of cleft or cranny that the first entrance of the Pinnotheres into any sort of bivalve can be easily under- stood. When the residence proved to be peculiarly secure, the shell of the crab would by degrees lose a hardness that THE OYSTER-CRAB 101 was no longer especially necessary. That the crab may be at times useful to the mollusc seems after all not so very improbable, for at the approach of an enemy so nervous a creature as a crab would no doubt begin to scuttle about and in this way communicate its terror to its more apathetic companion, which would then naturally close its doors against the danger. Dr. H. Woodward has recently recorded a remarkable instance of a Pinnothere* found encysted in a pearl-like formation of the pearl- oyster, Meleagrina margaritifera. Pinnotheres veterum, Bosc, and Pinnotheres pisum (Linn.) are common European and British species. Giard and Bonnier suppose that under the latter name several distinct species have been confounded. Its Zoea, long ago studied and drawn by Mr. Vaughan Thompson, is a singular-looking microscopic object. Among the names of other species some which indicate the animal's resi- dence may be mentioned, as Pinnotheres ascidiicola, Hesse, from the coast of France, the Japanese Pinnotheres pho- ladis, de Haan, and Pinnotheres lithodomi, Smith, from the Pearl Islands and Lower California. A similar indication is given in the generic name, Holothuriaphllus, Nauck. In ' The Civil and Natural History of Jamaica,' when speaking of a Pinnotheres, which he calls the Oyster-Crab, Patrick Browne says: 'This little species is generally found with the Mangrove oysters, in their shells, where they always live in plenty, and spawn at the regular seasons ; and such as eat the oysters, do not think them a bit the worse for being accompanied with some of these crabs, which they swallow with the fish. They are very small and tender, and nearly of the same length and breadth, seldom exceeding a quarter of an inch either way.' Hi/menosoma, Desrnarest, 1823, was established under a name invented by Leach, and signifying a membrana- ceous body. This is a character in which many members of the family partake. Hymenosoma orbiculare, Latreille and Desmarest, is a South African species. Halicarcimif, White, 1846, is closely allied to Hymenosoma^ but courts 102 A HISTORY OF RECENT CRUSTACEA attention for the sake of the species Halicarcinus (Fabricius), which is widely distributed over the Antarctic or Austi'al region, being the only Brachyurous Decapod, it is said, proper to that wide area of distribution. Mr. Haswell considers that the Elamene Hathcei of Milne- Edwards is probably the young male of this species, and that it is quite distinct from the original Hymenosoma Mathcei of Desmarest. IScopimera, de Haan, 1833, was established for the single species, Scopimera globosa, in which the arra of the chelipeds and the corresponding fourth joint (the so- called merus) of the hinder legs has the outer margin cartilaginous instead of crustaceous, with a transparent membrane in the flat part. This peculiarity explains de Haan's choice of a generic name, which means ' thighs with windows in them.' From the resemblance to the head of a drum these membranous pieces have been called 'tympana.' Dotilln, Stiinpson, was substituted for Doto, de Haan, 1833, a pre-occupied name. In this genus Dotilla f&nes- trata, Hilgendorf, from the East Coast of Africa, has the windows or tympana also in the sternum. Dotilla brevi- farsis, de Man, is from the Mergui archipelago. Dr. de Man makes Scopimera a synonym of Dotilla, but, if the two genera are united, Scopimera as the older name must take precedence. Hexapus, de Haan, 1835, is entirely devoid of the last pair of walking legs, so that instead of decapods these crabs have become octopods, and if the chelipeds are excluded and only the walking legs counted they may be regarded as hexapods, or six-legged crabs, and to this view the name of jthe genus refers. ThaumastoplcaK, Miers, 1681, it is said, ' is closely allied in all its characters and particularly in wanting the fifth pair of thoracic legs, to the genera Hexapus, de Haan, and AmwphopuS) Bell, but is distinguished from the former by the much greater development of the second ambula- tory legs and the structure of the outer [third] maxilli- pedes, whose nierus [fourth] joint is elongated and TRANSITIONAL FORMS 103 narrowed at its summit, where it is articulated with the next joint, and from the latter by the well-formed orbits and the entire absence of rudimentary fifth legs.' Those who are always sceptically inquiring for links in the chain of evolution and for the fine gradations which the trans- mutation of species postulates, may be invited to observe in this family the genus Pinnixa, White, in which the fifth legs are often short, the genus Amorpliopus, in which they are rudimentary, and lastly Thaumastoplax and Hexa^ pus, from which they have vanished altogether. Some curious facts relating^to the organs of vision in certain members of this tribe are worthy of mention. In the family Ocypodidas the genus Batliyplax, A. Milne- Edwards, 1880, contains but a single species. Specimens taken by the U.S.S. Blalie from depths between four and five hundred fathoms were found to have the eye-stalks very short, almost immovable, and with the corneae not developed. Accordingly the species was named typlilus, ' the blind.' But specimens taken from smaller depths by the Challenger agreed with the others in all respects except just this one, that they possessed small, distinct, terminal corneae. As these specimens were obviously not blind. Mr. Miers named them ' var. oculiferus.' In regard to another genus, also but more doubtfully included in the Ocypodidse, Professor Perrier cites the observation of A. Milne-Edwards, that in Geryon tridens, Kroyer, a species which descends to great depths, the eyes are brilliantly luminous. 104 A HISTORY OF RECENT CRUSTACEA CHAPTER VIII TEIBE III. OXYRKHYNCHA THE carapace is more or less narrowed anteriorly and usually rostrate, with the hepatic regions small, the bran- chial large. The epistome is generally large. The buccal frame is quadrate, with the anterior margin straight. There are nine pairs of branchiae, with the efferent chan- nels opening at the sides of the endostome. In this, as in the two preceding tribes, the afferent channels open behind the pterygostomian regions, in front of the base of the chelipeds. The first antennee are longitu- dinally folded. The third maxillipeds have the fifth joint articulated at the apex or at the front inner angle of the fourth. The verges of the male are exserted through the bases of the last pair of walking legs. This tribe of the ' sharp-snouted ' crabs is divided into two legions, the Maiinea and Parthenopinea. It has been observed in many cases that the two halves of the large liver are not separate, but united by a median lobe. The nervous system is said to attain a higher degree of cen- tralisation in this group of Crustacea than in any other, the ganglia of the trunk forming a single solid disk-like mass. Leijion 1. Maiinea. The basal joint of the second antenna? is well de- veloped, inserted beneath the eyes, and usually occupies a great part of the infra-ocular space. This legion contains three families, the Inachidaa, Maiidee, and Periceridee. Family 1 . Inachidce . The eyes are non-retractile, or retractile against the sides of the carapace. In general the orbits are not de- SPIDER-CRABS 105 fined, but there is often a well-developed prseocular and postocnlar spine. The basal joint of the second antennas is generally slender, sometimes moderately enlarged. The carapace varies in shape, being subtriangular, or trun- cately triangular or subpyriform, rarely suborbicular. The rostrum is simple or bifid, sometimes very short. The chelipeds never have the fingers excavate at the tips. The walking legs are sometimes very long. In both sexes the number of distinct segments of the pleon varies from four to seven. To this family belong nearly forty genera, three of which are included in the British fauna. Macropodia, Leach, 1814, meaning ' long-foot,' had been already called Macropus by Latreille, but that form of the name was preoccupied. By Lamarck in 1818 it was named Stenorynchus, 'narrow-snout,' a very appro- priate name but without any title to supersede the earlier Macropodia of Leach. Just as the title of the tribe Oxyrhyncha ought in accordance with its Greek original to be spelt Oxyrrhyncha, so should Stenorynchus have been spelt Stenorrhi/nchus. Part of this correction has been adopted in the commonly used form StenorhyncTvus, and naturalists have been so much tickled with the pleasing sound that, instead of leaving the monopoly of it to the Crustacea, they have employed it also among beetles, reptiles, birds, and mammals. The British species Macro- podia rostratiis (Linn.) is described in Bell's History under the name Stenorynckws Phalangium (Pennant). The specific name given by Pennant alludes to the resemblance which these crabs with long thin legs bear to the Pycno- gonids or Sea-spiders, and which has won for them the designation of spider-crabs. In spite of their long limbs they are a sluggish and slow-moving race, and in con- sequence are devoured in great numbers by other inhabi- tants of the sea. The fact that there are great numbers of them to be devoured shows that nature has not left them entirely without means of defence, of which some account will presently be given. Macropodia lonyirostris (Fabricius), which Bell calls Stenorynchus tenuirostris 10G A HISTOKY OF RECENT CEUSTACEA (Leach), is, like the preceding species, found both in British and Mediterranean waters, and is distinguished from the other species partly by the relatively greater length of the rostrum. Achceus, Leach, 1815, is so near to Macropodia that 'it is in fact only distinguished from it by the absence of rostral spines ; the rostrum in Acliceus being composed merely of two small acute or subacute lobes.' Of ten species enumerated by Miers only the type, Acliceus Oran- chii, Leach, belongs to the waters of Europe and Great Britain. Inachus, Fabricius, 1798, as at present restricted, con- tained in 1886 only six species, and these known only from European seas and the Western North- Atlantic. Three of these species are found in British waters, namely, Inachus dorsettensis (Pennant), Inachus dorynchus, Leach, and Inachus leptochirus, Leach. Leptopodia, Leach, 1815, has apparently but one species, Leptopodia sagittaria (Fabricius), with an extensive range in the warm waters of the Atlantic and of the West coast of America. Unlike the three preceding genera this has the rostrum not bifid, but simple. This beak is very long and serrate on the edges. The carapace is not spinous. The chelipeds in the male are rather slender and very elongate ; the walking legs are very slender and extremely elongated, with the seventh joint stiliforai. Next to this genus Leach placed one which he named Pactolus, with the species Pactolus Boscii, founded on a single female specimen in the British Museum from some unknown locality. Fabricius, he says, seems to have described it as the other sex of his Inachus Sagittarius. Pactolus has a body exactly like Leptopodia, but the legs are of moderate length, and of these the first three pairs have simple claws, while the last two pairs are didactyle, that is to say, chelate. In 1793 Fabricius said of his Sagittarius that in one sex the feet were of moderate size and all chelate, in the other six times as long and simple. In 1798, without any distinction of sexes, he states that eight of the feet are unguiculate and the last four pre- A DECEPTION DETECTED 107 hensile, thus making six pairs of legs, with a structural arrangement as regards three of them that would be unique among the Brachyura. At each date the species is said to come from the Isle of Guadeloupe. Leach rightly per- ceived that error and confusion were lurking somewhere, if it should not rather be said that they are conspicuous on the face of the two discordant accounts. Milne- Edwards in 1837, though with a confession of great un- certainty, institutes for the single genus Pactolus the tribe of the Pactolieiis, which he places among the Anomura. But soon after, in 1839, de Kaan with great acuteness ob- served, 'Pactolus, Leach, Zoological Miscellanies, vol. ii. tab. 68, seems to me to be made up of the thorax of a female Leptopodm sagittaria, to which the legs of some other animal have been united ; for the thorax of Pactolus, just as also the rostrum and abdomen, agrees with the female Leptopodia. The unlikeness in colour between the legs and the thorax in the figure referred to at once reveals the deception. Never are two alien forms found, agreeing exactly in the thorax, yet so disagreeing in the legs.' The principle here enunciated is worth remembering, as in some parts of the world there are dealers who delight and find profit and have also great skill in fabricating mon- strosities, sometimes such as have deceived the very elect. Nearly related to Inachus is the gigantic Macrocheira Kampferi, de Haan, 1839, of which mention has been earlier made. In Japanese it is called the insular crab. Huenia is another genus of this family instituted by de Haan in 1839. The name refers to the acutely trian- gular form of the carapace, and is derived from the Greek word VVLS, a ploughshare, a derivation which would have been hard to guess, had not de Haan obligingly mentioned it himself. At the foot of his plate 23 he names the figures ' 4. MAJA (Huenia) elongata n. 5. id. variet. 6. MAJA (Huenia) heraldica n.' But the species established in the text is Mfja (Huenia) proteus. The double generic name results from the inconvenient practice, still some- times followed, of splitting a genus up into sub-genera. Sub-genera, if they are worth anything, are pretty sure to 108 A HISTORY OF RECENT CRUSTACEA ' / ^-- . 5. ffuenia protem, de Haan, adult male, with separate figure of the pleou. 1 Flu. ti.llueniaproteits, de Haan, male. \ .' : - i . Fie. l.Huenia protem, de Haan, female, with separate figures of the pleon in a sterilised and 11 healthy specimen. PU/ZLES OF PARASITISM 109 be regarded as genera later on, and might therefore just as well be called so at first. But for his change of the specific names de Haaii had a reasonable though a rather singular excuse. After his plate had been engraved with the figures and names of two distinct species, based on the very great dissimilarity of the carapace in the male and female specimens at first available, he received a new series of specimens belonging to each form. These he found to agree in so many particulars that the protean form of the carapace no longer sufficed to separate them specifically, but had to be regarded as depending on the variations of age or sex. He here also observed that, as in several other Crustacea, there were what he supposed to be two forms of the female, the one ovigerous which he designates as genuine, the other sterile which he speaks of as spurious. In the present species he says that the pleon in the genuine females is of five segments, the fourth thick, very convex, with a longitudinal median impression, while in the spurious females it has seven segments, is lamellar and concave, with the fourth, fifth, and sixth segments dilated, the seventh narrower and truncate. The mystery of these so-called spurious females has been recently explained by Professor Giard. In studying the parasitic Crustacea, as well Isopoda as Rhizocephala, he was confronted by the statement which Rathke made in 1837, that of the many hundreds of Bopyrus which had passed through his hands he had never found one in any but a female Palcemon, and also by the statement which b'raisse made in 1877, that the males of Inachus, so far as he had observed, were never attacked by parasites, which he thought might be the result of the unsuitable shape of the narrow pleon in that sex. The parasitic groups will .be for after consideration, but it must here be mentioned that by careful investiga- tion Professor Giard arrived at the very interesting result that the specimens of the higher Crustacea infested by the parasites are as a rule more or less completely sterilised, and that the secondary sexual characters are considerably modified, so that the males acquire to some extent the 110 A HISTORY OF RECENT CRUSTACEA appearance of the females, especially in the widening of tl A pleon, which is the first characteristic of sex that would generally be looked for. It follows, therefore, that among the specimens which in old times have been regarded as spurious females many spurious males were beyond doubt included. It is also worth remembering that when the shape of the pleon leaves the sex of a crab ambiguous, that may be taken as an indication that some curious species of parasitic crustacean is likely to be found in some part of the organism. A large extension has been given to the family of the Inachidas by recent voyages of deep-sea exploration, and in some instances species which, when first discovered only a few years ago, were naturally supposed to be rare, have since proved to be cosmopolitan. Thus the little Lispognatfius Thomsoni (Norman), a delicate species with long slender limbs, taken at a depth of two or three hundred fathoms in the Faro Channel, and first described in 1873, has since then been taken at much greater depths and at places so wide apart as the Straits of Gibraltar, the neighbourhood of the Cape of Good Hope, and of Sydney in Australia. Ergasticus, A. Milne-Edwards, 1881, has two species Ergasticus Clouei, A. Milne-Edwards, and Ergasticus Naresii, Miers. The latter was taken near the Admiralty Isles in the Pacific, and recalls the name of the honoured captain of the Challenger ; the former was found in the Mediterranean and the Atlantic, and the name of the genus founded for it signifies ' a worker ' in remembrance of the French ship, the Travailleur, by which the type- specimen was dredged. Plafymaia Wyville-thomsoni (see Plate IV.), Gyrtomaia Murrayi, Cyrtomaia Suhmi, Eclii- noplax Moseleyi, represent new genera and species in this family instituted by Miers in 1886, in which the specific names have been chosen expressly to associate some of the finest of the Brachyura dredged by the Challenger with the names of its staff of naturalists. Platymaia and Cyrtomaia are also pointed out as of especial interest from their ' being Malayasian representatives of a section of the sub-family PI. iv. Platymaia Wyvill e -thomsoni Hippa talpoida Naxia hystrix H . talpoida Zoea,2 n - d sta(je H ta\po\tia.Zoea.last staoe Lambrus in termedius Catapagurus Sharreri Housed C . Sharpen Free A MOVING MUSEUM 111 Inachinas, hitherto represented only by types from Eastern America.' Among those types the nearest to Platymaia is supposed to be Euprognafha, Stimpson, 1870. In re- gard to Euprognatha rastellifera, Professor IS. I. Smith says : ' This is apparently by far the most abundant of all the Brachyura along our whole eastern coast south of Cape Cod in the belt from 50 to 200 fathoms depth In the U.S. Fish Commission dredgings off Martha's Vineyard, many thousands of specimens were often taken at a single haul of the trawl.' Family 2. Mai idee. The eyes are retractile within the orbits, which are distinctly defined, but often more or less incomplete below or marked with open fissures in their upper and lower margins. The basal joint of the second antennae is always more or less enlarged. The family includes about thirty genera, three of which are known in British localities. Maia, Lamarck, 1801, is a genus well known rather to the south than the north of Great Britain in the species Maia squinado (Herbst). It is a large, eatable, and, in the south-west of England, an extremely abundant species. Its great inflated carapace, covered with prickles and fur, gives it a ready place in the memory when once it has been noticed. A pretty little amphipod, called Iscea Montagui, Milne-Edwards, with the sixth joint of its legs much widened, seems to have been specially adapted for ranging about this hirsute and prickly crab, the only place in which it is found. The convenience of the residence may be in- ferred from the fact, previously noticed, that from time to time a score of other species of Amphipoda find it their interest to occupy the same station. The crab, according to Herbst, is known as Squinado in Provence. In Corn- wall it is called the Corwich, and Bell was told that in those parts several dozens could be had for sixpence. But even this does not give so ample an idea of its abundance as is conveyed by Olivi in his ' Adriatic Zoology ' of a hundred years ago. He declares that in summer the crabs 112 A HISTORY OF RECENT CRUSTACEA are dispersed upon the shore, but that in winter the females collect on the deeper rocky ground in particular spots in a great crowd, and pile themselves up in such numbers that they form a sort of mound, which from the depth of eighty to a hundred feet ascends until the glimmer of it can be eeen at the surface of the water, and that then the Istrian fishermen go out with two, four, or six boats, surround this living tower with their nets as easily as possible, and so make a speedy capture. Professor Stalio, in 1877, en- dorses this wonderful tale, except that in his account the boats employed are only two or four, and the instinct which leads these creatures to cling together and climb up one on another's back only produces a great pile of several feet in height. Yet anything much less than Olivi's submarine mountain of crabs would scarcely be visible from the sur- face at the depths which he mentions. The Mediterranean possesses another closely allied spe- cies, Maia verrucosa, Milne-Edwards, smaller in size, and covered with warts or tubercles, instead of spines or prickles. This little crab led the way in quite recent years to some observations that throw a new light upon the mental powers of the Crustacea. A great many of the Oxyrrhyncha have at all periods excited the surprise of collectors, when dealing for the first time with living specimens, by their often extreme un- tidiness. They are overgrown with algss and ever so many kinds of sedentary animals. They are undoubtedly them- selves slow-moving creatures, and it was not unnaturally supposed tha,t these colonies with which they were encum- bered and disfigured were at once a proof and a result of their extreme sluggishness. Dr. Graeffe had once occasion to carry into the aquarium at Trieste a specimen of Maia verrucosa which had been stripped of most of its vegetable costume. He happened to place it in the same vessel with a large mass of the polyp known as Dead Man's Fingers. The next day, to his astonishment, he found the whole back of the Spider-crab covered with pieces which had evidently been snicked out of the Alcyonium. To make sure, he kept watch, and at length had the sweet satis- HOW CKABS PUT THEIR CLOTHES ON 113 faction of seeing how the crab slowly stepped up to the polyp-mass, and with its claws tweaked off small points of the branches. At first it let them lie on the floor of the aquarium, but later on fished one of them up again with its claw, which it bent over the back of its carapace, and there among the fur it planted the fragment of the polyp with the severed surface downwards ! Further experiments showed that not only in the species of Maia, but also in those of Pisa, Macropodia, Inaclms, and other Oxyrrhyncha, the foreign organisms were fastened to the crabs' bodies by the crabs themselves. That the object was concealment by the wearing of a mask was obvious, since the costuming was never at random, but always in strict agreement with the surroundings. Moreover, these marine zoologists know what sponges and polyps can be chopped up without causing mortality in the fragments. The pieces they plant are pieces that will live and thrive, and, as Dr. Graeffe observes, the keepers of aquaria have only to consult the crabs to learn what kinds of sea- animals will bear being thus transplanted piecemeal. For keeping on their living mask Dr. Graeffe found that the natural coats of these Crustacea were furnished with hairs varying in arrangement and shape in the different genera and species, some of the hairs being fish-hook-shaped, others clubbed, and others simply tapering, but all more or less serrate, the simple ones sufficing to detain a coating of slimy mud, while the others hold captive the living organisms. Dr. Graeffe published his observations in 1882, but already in 1878 Dr. Eisig had reported of a species of Inachus that he had seen it plucking Hydroids and plant- ing them on its spines and hairs, and Dr. C. Ph. Sluiter in 1880, when establishing the new species Chorinus -alc/atec- tus, described its way of spitting little fragments of algas on the strongly bent booklets of its body and legs, to mask itself from its enemies and its prey. Additional details of great interest were published in 1889 by the Swedish naturalist Dr. Carl W. S. Aurivillius. Hyas, Leach, 1813, comprises but few species, two of I 114 A HISTORY OF RECENT CRUSTACEA which belong to Great Britain and are also extensively dis- tributed in the North Atlantic. These are Ilyas araneus (Linn.) and Ilyas coarctatus, Leach. In a tiny specimen of the latter species, taken from off the carapace of the mother, small spines or tubercles are observable on both sides of each of the two divisions of the rostrum, on the outer side of the second antenna?, and on the eye-stalks. These minute characters do not reappear in the adult. The two species mentioned are very abundant on the coast of Sweden, and Aurivillius found that they were almost without exception dressed up either in pieces of different algas (almost always Florideas) or of shallow-water sponges, or with Hydroids, tubicolous Annelids, Polyzoa, Cirri- pedes, or Ascidians simple or compound. His experiments showed him that, if some of these settled rather by the crab's permission than its active interference, yet they had been originally under its control, while in most cases the colonists had been actually planted and forced at the will of the crustacean to occupy their several stations. He found, just as Mr. David Robertson of Cumbrae had done, that his specimens of Hyas were capable not only of dress- ing but of undressing themselves. Of the effectiveness of their disguises he had often had practical experience, when upon visiting his aquarium in the morning he was unablo to find specimens which he had placed thei*e overnight, and which he at first thought must have escaped. Close inspection and the help of a magnifying glass, however, would always show that they were present, but that they had so decked themselves out with the vegetables and animals around them as to lose all invidious prominence. By transplanting into an environment of sponges some that had clothed themselves in bright-coloured algas, he ascertained how accurately they knew their business, for they laboriously picked off the gay colours, and stuck themselves over with fragments of sponge in their place. The chelipeds of these crabs are adapted by length and by the flexibility of the joints to reach to the different parts of the body which require dressing up. The hooks and hairs which hold on the tags and patches have been already A CAREFUL TOILETTE 115 considered. One curious point as to their distribution may be noticed. When the female is loaded with eggs, the basal segment or segments of the pleon are forced upwards so as to need concealment like the carapace. The result is, in some at least of the Oxyrrhyncha, that hooks for the attachment of foreign objects occur upon these segments in the females but not in the males. While dressing themselves the crabs invariably bring each portion of their intended coat to their mouths as if PlG. 8.Chorinus aculeatus, Milne-Edwards [AuriviUius]. they were going to eat or at least to taste it. AuriviUius noticed that if a piece did not hold firm where the crab was seeking to plant it, recourse was had again to the mouth, and if the piece still proved intractable, it would be brought to the mouth a third time and then tried on a fresh spot. The object of this assiduous application to the mouth is, he thinks, that each piece may be well licked, a secretion from the mouth organs, especially the first pair of maxillipeds, bestowing the requisite adhesive i 2 116 A HISTORY OF RECENT CRUSTACEA character. Considering the tolerably ruthless manner in which the crab gathers the constituents of its costume, one need not wonder at their needing a little emollient ointment. Under the circumstances their natural ten- dency to adhere might otherwise remain for some time dormant. Ghorinus aculeatus, Milne-Edwards, as depicted on the preceding page, is suggestive of a wardrobe provided with a truly enviable number of pegs. In regard to a closely related species, Chorinus longisplna, de Haan remarks that to the hooked setas of the thorax and legs marine odds and ends adhere so closely that they can scarcely be removed without damaging the setae. He is thinking only of man's rude handling, for, however remorseless such a crab may be towards its surroundings, we may feel assured that its deft fingevs will do no violence to the well-appointed furni- ture of its own carapace. Pisa, Leach, 1813, is open to the suspicion of being a synonym of Arctopsis, Lamarck, 1801. There are several species of this genus in various parts of the world. The two known in English and Irish waters occur also in the Mediterranean and have a considerable range north and south. These are Pisa tetraodon (Pennant) and the species which Bell calls Pisa Gilbsii, Leach, a name which must be wrong, whatever other is right. Miers with some hesi- tation adopts for it the name Pisa (Arctopsis) tribulus (Linn.). Naxia, Milne-Edwards, 1834, is narrowly distinguished from Pisa by the accessory spinules of the two-horned rostrum. Naxia hystrix, Miers (see Plate IV.), was ob- tained by the Challenger at Amboina. Lissa : Leach, 1815, is a genus apparently near to Pisa, but with a rostrum consisting of two truncate laminar horns side by side, which are somewhat wider at the ex- tremity than at the base. It was formed for the Mediter- ranean species Lissa chirac/ra (Fabricius), which is deep red in colour, and has the legs so covered with protuber- ances that its specific name, meaning ' gout in the hand,' is not inappropriate, although it so happens that the hands PROTECTIVE PEEIL 117 of the chelipeds are almost the only smooth part about it. It is said by Stalio to be sensitive to changes of tempera- ture, and at any increase of cold to crouch closely in the crevices of the rocks, but as he also says that its habitat is at a depth of thirty to forty fathoms, it is not easy to understand how this valetudinarian shrinking has been ascertained. The crab is only about two inches long, and according to Herbst is commonly covered with worm-tubes, corals, algas, and mud, to such an extent that it is scarcely to be recognised or to be taken for a living creature. Ghionoecetes, Kroyer, 1838, is a northern genus, with a name meaning ' the snow-dweller,' founded for the Greenland species Chionoecetes opilio, which, according to Professor S. I. Smith, is taken rarely in the deep water off the New England coast. ' It is,' he says, ' one of the largest arctic crabs, and occasionally attains gigantic pro- portions.' In the largest specimen that he examined the span of the walking-legs was two feet eight inches. The specimen figured by Kroyer in Gaimard's voyages was, he says, even somewhat larger, but though the figure occupies the whole extent of the folio plate, I do not find that even with the second pair of legs which are the longest or with the third pair which are inserted at the broadest part of the carapace could it span more than twenty-eight inches. Antiiibinia Smithii, M'Leay, is a South African species which Krauss observed in its native haunts on the per- pendicular wave-lashed cliffs of the headland at Natal. Its legs are powerful and have the terminal joint bent into a strong hook by which the crab can fasten on to the pores of the rock. Its body is rounded off and has a very hard horny shell well adapted to resist the continual beating upon it of the surf. Among the bright and dark green algae, and coloured like them, it sits almost completely motionless and lets its food be floated to it by the ever- moving sea. When Krauss wished to take some speci- mens away from their dangerous position, they clung so tight that he had to use considerable force to disengage them, and was in consequence several times overtaken by the returning waves before he could effect his purpose. It 118 A HISTORY OF RECENT CRUSTACEA is pleasant to see how creatures comparatively feeble may sometimes find security in stations the most unpromising and the most exposed. The whole tribe of the Oxyrrhyn- cha are indeed often placed at the head of all the Crustacea in honour of the ready wit and resource which so many of them display. Scyramathia Carpenteri (Norman) is a remarkable crab first observed on the Porcupine expedition in the Channel between the Faro and Shetland Isles. It was afterwards obtained abundantly by the Travailleur from great depths in the Bay of Biscay, and again the Norwegian North- Atlantic expedition trawled it from a depth of 220 fathoms about twenty miles off the west coast of Norway. According to the description of it by Professor Sars, ' the whole surface of the body is invested, as it were, with a dense, felt-like covering, which, on closer inspection, is found to consist of two different kinds of cutaneous ap- pendages. Innermost, crowded together, are observed numerous small tuberculiform excrescences, which, at the first glance, may be readily taken for granulations on the skeleton of the skin, but, after a closer examination, are seen to be of a totally different character, since they have not only a soft consistence, but admit of being scraped off with the greatest facility. On treating these protuber- ances with a solution, of potash, they are found to be true cutaneous vesicles or capsules, that, with a broad basis, are attached to the skeleton of the skin and sup- ported in the middle by a slender chitinous-like rod, of which the point projects more or less distinctly forward from the top. Between these peculiar cutaneous appen- dages, and projecting considerably beyond them, are short and comparatively stiff hairs, somewhat unguiform at the extremity, and crowded together, in particular on the anterior part of the dorsal surface of the carapace, which thus acquires a velvety appearance.' The rostrum also is highly characteristic. It is divided from the base into two straight, strongly divergent, branches, about half as long as the carapace. They are cylindrical at the base, but taper gradually to a dagger-like point, and SOME NAMES DISENTANGLED 119 are thickly covered with hair. There is, according to Sars, a possibility, which, however, S. I. Smith thinks an impro- babilit} T , that the species may be the same as one earlier but all too briefly described by Stimpson, from the coast of Florida, under the name Scyra umbonata. The speci- men taken by the Porcupine was first described as Amathia Carpenteri, but the genus Amathia, Roux, has a pre-occu- pied name which has in consequence since been changed, by S. I. Smith, to Anamathia, and Professor A. Milne- Edwards discovered that the species Carpenteri could not be included in that genus. At the same time he noticed its likeness to Stimpson's species above mentioned, and framed for it the new genus Scyramathia. From the fore- going remarks it will easily be understood what suggested the composition of this generic name, but it must not be forgotten that Scyramathia belongs to the family Maiidee, whereas Anamathia stands in the previously described Inachidge, and Scyra (though to the exclusion of Stimp- son's species umbonata) is a genus belonging to the next family, the Periceridge. Family 3. Periceridce. The eyes are retractile within the small circular and well-defined orbits, which are not incomplete as in the Maiidge. The basal joint of the second antennae is well developed, and constitutes a great part of the inferior wall of the orbit, the joint being in general much enlarged. The family contains about twenty genera. Pericera, Latreille, 1829, of which the type is Pericera cornudo (Herbst), 1804, has been despoiled of many of its species by Miers, who has transferred them to Macro- coeloma, a new genus which he instituted in 1879. Of the species Macrocoeloma trispinosa (Latreille) Mr. Ives says that Yucatan specimens when alive are of a bright scarlet colour. In the Challenger species, Macrocoeloma concava, Miers, from Bahia and Fernando Noronha, the body and limbs are covered with a short close pubescence and with some longer curled hairs. Its colour in spirit is 120 A HISTOEY OF EECENT CEUSTACEA yellowisli-brown, but this is little or no guide to what its colour may have been when living. The specific names in this genus ought to have either masculine or else neuter terminations, but many naturalists seem to suppose that any generic name ending in -a is a feminine form, which is far from being the fact. In this family the genus Libinia, Leach, 1815, contains several species, and Mitlvrcux (Leach), Latreille, 1817, a very large group. Of Libinia emarginata, Leach, Miss Mary Rathbun, in her recent revision of the Periceridas, says that in Long Island Sound occasionally this species by its numbers ' so interferes with the steam oyster dredgers that work is abandoned until the crabs (which are known to the oystermen as " spiders ") have passed over.' Letjion 2 . PartJienopinea. The basal (or true second) joint of the second antenna? is very small and embedded with the next joint in the narrow gap between the ' front ' and the inner orbital angle, the intraocular space being mainly occupied by the inferior wall of the orbit. Family 4. Parthenopidce. The eyes are usually retractile within the small circular and well-defined orbits ; the lower wall of the orbit is con- tinued to within a very short distance of the ' front.' The second antennae are very slender ; the basal joint does not as in the Pericerida3 constitute a great part of the inferior orbital margin, but is very small, seldom reaching the ' front,' and with the next joint occupies the narrow gap intervening between the ' front ' and the inner angle of the orbit. (In Ceratocarcinus the antennas are completely excluded from the orbits.) Some fifteen or twenty genera are reckoned in this family, of which only one is known in the waters of Great Britain. Ewnjnome, Leach, 1814, has not yet received many THE GEE AT WAETY CEAB 121 additions to the type species Eurynome aspera (Pennant), for though the names scutellata and boletifera have been given to forms taken in the Mediterranean, it is probable that they are not distinct from, or at most are only varieties of, the species found on the British coasts. It is, as might be guessed from the names, a species rough with warts or tubercles. The walking-legs are short, but the chelipeds in the male are elongate, being nearly twice the length of the body according to Bell, but according to Leach three times its length. Eurynome tenuicornis, Malm, from Bohusliin, Gullmarsfjord, is there found to- gether with Eurynome aspera. Parthenope, Fabricius, 1798, has in its type species, Parthenope horrida (Linn.), an animal of truly remarkable appearance. It is recorded from the West and East Indies, and has been called the great Warty Crab or stigmatised as the Lazy Crab. Its carapace is pentagonal, broader than long. While this and the legs are covered with warts and spines, the pleon is said to be full of pits, almost as if eaten through. The chelipeds are large and long. From the picture of it given by Herbst one might suppose that it was intended to look like a piece of light-red sand- stone overgrown here and there with green algae. Lambrus, Leach, 1815, unlike the two preceding genera, suffers from no paucity of species. So numerous indeed are they that in 1878 Professor A. Milne-Edwards deemed it expedient to subdivide Lambrus into ten genera, in- cluding in the number Solenolambrus, Stimpsou, and Mesorhoea, Stimpson. The species are distributed over all the warmer seas of the world, and some occur in the Medi- terranean. Of these Lambrus macrochelos (Herbst), mean- ing the Lambrus with long chelipeds, justifies its name, but almost puts its body out of countenance, seeing that the arms in question are nearly four times as long as either the length or breadth of the carapace. In Lambrus inter- medius, Miers (see Plate IV.), from the Corean Seas and Torres Strait, the disproportion between legs and trunk is less exaggerated. In the genus at large it is remarked that, apart from larval metamorphoses, so many variations 122 A HISTORY OF RECENT CRUSTACEA of form are undergone during progress to the adult con- dition, that, without a considerable series of specimens, young and old of the same species must often almost in- evitably be considered as distinct. Heterocrypta, Stimpson, 1871, contains but three species, and those of small size but singular appearance. One of these, Heterocrypta Maltzani, Miers, which has been taken at Goree Island, at the Azores, and off Senegambia, is also an ornament of the Mediterranean, having been taken by the Travaitteur at a depth of about 250 fathoms off Toulon. The Mediterranean form was at first named Heterocrypta Marionis, after the distinguished French zoologist, but it has since been found to be the same species as Heterocrypta Maltzani. THE POINT EXPLAINED 123 CHAPTER IX TRIBE IV. OXYSTOMATA THE carapace is convex or depressed, with the antero- lateral margins arcuate or orbiculate ; or even subglobose ; or more or less oblong, with subparallel or slightly con- vergent margins (Dorippidse). The epistorne is very much reduced or rudimentary. The buccal frame is more or less triangular, nearly always produced and narrowed forwards with the margins anteriorly convergent. The afferent channels to the branchiae open either behind the pterygostomian regions and in front of the chelipeds, or, more rarely, at the antero-lateral angles of the palate (Leucosiidae). The efferent channels open at the middle of the endostome which is produced forwards. There are six to nine pairs of branchiae. The first antennae fold longitudinally or obliquely. The third maxillipeds have the fifth joint articulated at the inner or the outer front angle or at the apex of the fourth, beneath which it is often concealed. The verges of the male are exserted either from the surface of the sternal plastron or more usually from the bases of the fifth pair of legs, which are either adapted for walking or for swimming, or are feeble and raised upon the dorsal surface of the carapace. It is the narrowing anteriorly of the buccal frame or 1 mouth-cavity ' that gives the name of ' sharp-mouths ' to this tribe, which is divided into four families, the CalaiD- pidae, Matutidae, Leucosiida?, and Dorippidse. Family 1 . Ca la 2 ip idee . The afferent channels to the branchiae open behind the pterygostomian regions and in front of the chelipeds. 124 A HISTORY OF RECENT CRUSTACEA The third maxillipeds have the fifth and following joints not wholly concealed by the fourth joint. The verges of the male are exserted from the bases of the fifth pair of legs. There are about ten genera included in this family. Calappa, Fabricius, 1798, contains some fifteen species, which are not a little remarkable in appearance. This is partly due to the form of the carapace, much narrowed in front where the short-stalked eyes twinkle cunningly, but widened behind with shield-like expansions over the bases of the legs. More singular, however, is the development of the chelipeds, which have a very flat crested hand of great size, yet the whole limb withal so arranged that the pair can be concealed beneath the body to which in that position they might be said to supply an operculum or in- complete ventral carapace. Of Calappa' granulata (Linn.) Stalio says that, when it is compelled by fear of some enemy or by the force of the waves to leave its crevice in the rock, it draws together its walking-legs under the ex- panded parts of the carapace, makes its chelipeds meet, and, being thus reduced to the shape of a ball, launches itself into the deep. Unfortunately for it, the scouring of the waves often throws it up on to the shore, where con- tinuous rolling upon the pebbles puts an end to its exist- ence. This is a waste of what would otherwise form an agreeable morsel. It maybe eaten with a good conscience, since it is itself very voracious, and when in pursuit of prey not to be intimidated. Judging from the contents of the stomachs of various Crustacea, de Haan was able to decide that Calappa, Matuta, and Dorippe feed on other Brachyura, Leucosia on species of Palcemon, Ranina on fishes and starfish. Calappa gallus (Herbst) is common to the Atlantic and the Pacific. The crested claws here carry to an almost comical extreme the resemblance to the head of a cock, which they exhibit more or less throughout this genus. Calappa depressa, Miers (see Plate II.), from the South Australian coast, is one of the smaller species and a recent contribution to science. Paracyclois, Miers, 1886, is a genus in which the cheli- peds and walking-legs agree with those in Galappa and A QUESTION OF PEIOEITY 125 Cryptosoma, and it is considered to connect Gryptosoma, Brulle, and Platymera, Milns-Edwards, with Galappa through such forms as the above-mentioned Galappa [fall as (Herbst), but Paracyclois is distinguished from the first two of these genera by the absence of any lateral spine on the margin of the carapace, and the broader basal joint of the second antennas, ' and from Galappa by the absence of the clypeiforni prolongations of the carapace, which are represented by a slight protuberance of the postero-lateral margins in Paracyclois^ which protuberance bears several strong spines.' The type species of this curious genus, Paracyclois Milne-JEdwardsii, Miers, was dredged north of the Admiralty Isles from a depth of 150 fathoms. Gryptosoma cristatum, Brulle, was depicted in Webb and Berthelot's ' Hist. Nat. des lies Canaries/ and the genus was instituted at page 16 of that work, for which Miers gives the dates 1836-1844. Milne-Ed wards in 1837, while his own pages were passing through the press, refers to Brulle's genus and species as about to be published. In the same year, 1837, de Haan published a new genus and species, Cycloes granulosa, from Japan. In 1841 he states that Brulle's species is clearly the same as this, and in 1849 he repeats the remark as an example of wide distribution, the very same crab being found at the Canaries and in the waters of Japan. But he retains the name Cycloes, being evidently, and perhaps rightly, under the impression that it had priority over Gryptosoma. Orithyia, Fabricius, 1798, is strongly distinguished from the other genera of this family by the natatorial character of the last three pairs of legs, which have an ovate terminal joint, as in the Portuiiidae. The three preceding pairs of legs have also the terminal joints flat- tened, and the others more or less compressed, as is usual in species apt for swimming. There appears to be only one species, found in the Chinese Sea, and called bima- culatus by Herbst in 1790, and mammillaris by Fabricius in 1793. Herbst, whose specific name must prevail, says that ' without dispute this crab is one of the most beautiful and most rare.' 126 A HISTORY OF EECENT CRUSTACEA "Family 2. Matutidce The characters are the same as in the CalappidaB, ex- cept that the third maxillipeds have the three terminal joints concealed beneath the triangular acute fourth joint. The family contains four genera. Matuta, FabriciuSj 1798, is regarded as the genus among the Brachyura in which the adaptation for swim- ming attains its highest development. In the last pair of legs the oval terminal joint is supplemented by a very broad expansion of the preceding joint. Moreover, the other three pairs of legs are natatorial, having broad flat- tened joints, in particular the .pair next the chelipeds evi- dently forming paddles of great power. Nevertheless, none of these limbs are fringed with hairs, the ordinary armature of swimming legs. The sufficient reason as- signed for this is that the crab's safety often depends upon the extraordinary rapidity with which it can bury itself in the wet sand. Its flattened joints have sharp points and edges, with the digging powers of which any fringe of fur would seriously interfere. As it is, they can slip themselves under the sand in a moment, and before the troubled water has cleared over their departing footsteps the traces of them are smoothed and lost. Yet sometimes, it is said, their movements may be perceived under the feet of a person walking along the shore. Among the Japanese specimens of Matuta victor, Fabricius, de Haan observed some of what he calls ' spurious females,' but he mentions no peculiarities in them except their smaller size. If Paulson's identification be right, the name of this species should become Matuta lunaris (ForskSl.) Ifepdt'tis, Latreille, 1806, has, according to de Haan, the third joint much shorter than the fourth in the third maxillipeds, whereas in Matuta those two joints are equal in length. Hepatus princeps (Herbst) appears to be the proper name of the type species, which occurs both in the East and West Indies. This genus, and with it BEAUTIFUL COLOURING 127 Stimpson, and Actoeomorpha, Miers, are distinguished from Matuta by having the terminal joints of the legs adapted, not for swimming, but for walking. Osachila and Actceo- morpha are, according to the author of the latter genus, perhaps identical. Family 3. Leucosiidce. The afferent channels to the branchias open at the antero-lateral angles of the endostome and not behind the pterygostomian regions. The third maxillipeds have the three terminal joints wholly concealed by the triangular fourth joint. The verges of the male are exserted from the sternal plastron. In this family twenty-nine genera are accepted by Miers in 1886. One of them is included in the fauna of Great Britain. Leucosia, Fabricius, 1798, contains numerous species, which occur in the littoral and shallow waters of the Indo- Pacific region. They are often remarkable for the beauty of their colouring, testimony to which is borne in the names of the species, Leucosia splendida, Haswell, and Leucosia pulcherrima, Miers. They have the frontal re- gion of the carapace narrowed and produced anteriorly, and in front of and above the bases of the chelipecls there is a pit defined by a series of granules. This, which is continued as a shallow excavation beneath the postero- lateral margins of the carapace, has received the name of the thoracic sinus. The walking-legs are small, succes- sively shorter from the front to the rear. The pleon of the male in some species has all the segments united ex- cept the first and last, in others the third coalesced with the fourth, and the fifth with the sixth. A figure of Leucosia australiensis, Miers, is given on Plate II. The type species, scabriuscula, Fabricius, has been transferred to the next genus. Philyra, Leach, 1817, is a genus nearly allied to Leu- cosia, with a similar range, and also containing several species. But, among other distinctions, the ' front ' is 128 A HISTORY OF RECENT CRUSTACEA broader and not at all prominent, and there is no ' thora- cic sinus.' Philijra pisum, de Haan, is said to be infested, FIG. y. Myrafugax (Fabricius) [de Haan]. like Leander squilla and Leander serralus, by a Bopyrus, making the sides of the crab bulbous. De Haan remarks that he never saw the Bopyrus in true females, and that in males they occupy the right side, in spurious females SOMETHING ABOUT StFE-GENERA 129 the left side, of the crab. The parasite referred to would no doubt now stand under some other generic name. Myra, Leach, 1817, is another genus of common occur- rence throughout the Indo-Pacific region, of which the species Myra fugax (Fabricius) has been frequently re- named. It is remarkable for the great length which the slender chelipeds sometimes attain, and which have caused the Japanese to call it the long-handed crab. EbaUdjIjQSick, 1817, has an extremely extended range, and includes numerous species, among which several occur in European seas, and four of them in the waters of Great Britain. These four are Ebalia tuberosa (Pennant), Ehalift iumefacta (Montagu), Ebalia Cranchii, Leach, and Ebalia nux, Norman. It is curious that Bell, in his ' History of British Stalk-eyed Crustacea/ should have thought it right to follow Leach in calling the first two of these respectively Ebalia Pennantii and Ebalia Sryerii, while he relegated the earlier names to the synonymy. The resemblance which these little creatures, with their legs all tucked up, assume to a rugged little fragment of stone has been already mentioned. CompariDg Ebalia with a genus Plilyxia instituted by Bell in 1855, Mr. Miers says : ' The genera Ebalia and Plilyxia are now connected by so many intermediate species, that not one of the distinctive cha- racters mentioned by Bell can be regarded as constant. I propose, therefore, to unite these genera, but to separate the species under two primary sections or sub-genera (for which the names Ebalia and Phlyxia may conveniently be retained) as follows : ' I. Front slightly concave or truncated, not quadri- dentated (Ebalia).' This is followed by a list of twenty- six species. ' II. Front with four distinct (usually tuberculiform) lobes or teeth, including the tooth at the interior angle of the orbit (Phlyxia').' This is followed by a list of seven species, in regard to which it is pointed out that all are restricted to Australia. The convenience of having a generic name to indicate so small a mark of separation may well be questioned, but the inconvenience of the sub- K 130 A HISTOKY OF EECENT CRUSTACEA generic name scarcely admits of question, especially when it leads to the possibility of a creature being called ' Ebalia (Phlyxia) undedmspinosa (Kinahan), var. orbi- cularis,' a name which is even then incomplete without the addition of the names (Haswell) Miers, to show that Mr. Miers has made Haswell's Phlyxia orbicularis a variety of Kinahan's Ebcdia undedmspinosa. Ixa, Leach, 1815, has perhaps, according to Mr. Miers, only one species, though five have been named. This one is the Ixa cylindrus (Fabricius), called Ixa canaliculata by Leach. It is widely distributed in the Indo-Pacific region, and has a very remarkably shaped carapace, transversely rhomboidal or somewhat elliptical, and prolonged at either side into a cylindrical lobe, which is often as long as the width of the main portion of the carapace. Oreophorus, Etippell, 1830, ' the hill-bearer,' and Spelceophorus, A. Milne-Edwards, 1866, ' the cave-bearer,' have names referring to the prominences and depressions in the carapace. Family 4. Dorippidce. The afferent channels to the branchias open behind the pterygostomian regions, and in front of the chelipeds. The three terminal joints of the third maxillipeds are not concealed by the fourth joint. The last pair or last two pairs of legs are short and feeble, and raised on the dorsal surface of the carapace. The verges of the male are ex- serted from the sternal plastron. The family includes eight or nine genera, the position of Cyclodorippe, A. Milne-Edwards, being rather doubtful, since in it there are no afferent openings to the branchias in front of the chelipeds. Dortppe, Fabricius, 1798, has a wide range, and in- cludes several species. One of them, Dorippe facclrino (Herbst), is found both in the Mediterranean and at Hong Kong. The first two pairs of walking-legs are long, and enable the creature to run fast. The two following pairs are very slender and short. To account for their dorsal position various reasons have been suggested. Herbst LOOKING- LIKE A BUFFOON 131 says that the crab can run either way up. Another view is that these hind legs lift foreign objects on to the carapace, .2* "3 > ^ ll ' 3 2 -S ho s.a s2 $ g.3 ^ - >s of the billowy ocean. Benthesicymus has a submembran- ous integument, exopods to the limbs as in Penceus, podo- branchiaa as in Aristeus, and the last two pairs of trunk- legs longer than the preceding pairs. One of the species, Benthesicymus pleocanthus, Spence Bate, was trawled from a depth of 3,050 fathoms in the North Pacific, while other specimens were taken twenty degrees further south in the smaller depths of 450 and 1,050 fathoms. Bentlionectf* is specially characterised by the multiarticulate flagelliform dactyli, that is the subdivided terminal joints, of the last two pairs of trunk-legs. Xipliopeneus, S. I. Smith, 1885, and Benthoecetes have a corresponding peculiarity in the propodi or sixth joint of the same limbs. In some of the 220 A HISTORY OF EECENT CRUSTACEA species of the deep-sea genera, such as Benthesicymus and Gennadas, Spence Bate, the eye-stalk sends out a promi- nently pointed tubercle, with a small circular lens at its extremity, served by a distinct branch of the optic nerve, this single lens being very translucent and without trace of pigment. Gennadas received its name, meaning ' of a noble race/ because it ' approximates nearer than any other to the little crustacean named Penceus (Kolga) spe- ciosus in Salter and Woodward's map of fossil Crustacea.' Peteinura, Spence Bate, 1888, meaning < flying- tail,' is established for a single species Peteinura gubernata (see Plate IX.), founded 011 a single specimen an inch long, taken at the surface of the Atlantic at night time. There can be no doubt that the supposition is justified that the specimen is an immature form. There is a very long slender rostrum such as is common in larval forms, but the strangest peculiarity is at the other extremity of the animal. The sixth segment of the pleon, which is about as long as the four preceding segments together, carries a pair of uropods of which the inner branch is small and rudimentary, whereas the outer is nearly as large as the rest of the animal, a truly prodigious rudder ! If ever the tail could wag the dog, one might expect a parallel to that phenomenon in this instance. Cerataspis, Gray, 1828, of which Cryptopus, Latreille, 1829, is a synonym, has been lately shown to have ' almost all the characters of the typical Penaeidae.' Gray referred his Gerataspis monstrosus to the ' Fam. Nebaliadas (Les Schizopodes Latr.),' but Giard and Bonnier say, ' the antennules, the antennae are absolutely those of the Pengeidas ; the second maxilla possesses the four charac- teristic plates ; the endopod of the first maxilliped is five- jointed, the second maxilliped is geniculate, the third is transformed into a locomotive appendage; the thoracic legs are provided with long swimming branches (exopods) ; the first three pairs end in chelas ; the last two are simple, &c.' Referring also to P. J. van Beneden's discovery of the nauplian embryo, they remark that ' among the Schizo- pods the nauplian embryo has only as yet been observed LONO NAMES FOE SHORT LARV^ 221 in the JUwphausice, while on the contrary it is very frequent among the Peneeidas.' Family 2. Sergestidce. The branchial system is impoverished or lost, the epipodal plates and podobranchial plumes, when present, being restricted to rudimentary structures on the second maxillipeds. The first pair of trunk-legs, and some- times the second, are simple, the chelge of the third are minute, the fourth and fifth pairs are feeble, rudimentary, or absent. The genera assigned to the family are Sergestes, Milne- Edwards, 1830 ; Acetes, Milne-Edwards, ISoCT; Petalidium, Sp. Bate, 1881 ; ScicMwris, Sp. Bate, 1881 ; and Lucifer, Vaughan Thompson, 1829, a pre-occupied name altered to Leucifer by Milne-Edwards in 1837. A very few re- marks must suffice on the discrimination of these genera. In Sergestes the last two pairs of trunk-legs are rudi- mentary, in Acetes the last but one is reduced and the last is wanting, in Leucifer both pairs are absent. In Sergestes the arthrobranchias are wanting, in Petalidium they are found on the second and third maxillipeds and the first three pairs of trunk-legs. In Sergestes, Professor Smith remarks, the branchia? are compound phyllobranchiae, while those of Pencens in the preceding family are com- pound trichobranchias. The larval forms of Sergestes have been partitioned into genera and species. The youngest form known is desig- nated JElaplwcaris by Dohrn (see Plate IX.) ; another, and presumably later form, is called Platysdcus by Bate ; this is followed by Acanthosoma, Glaus, and that by Mastigopus of the same author. The species known as adults are very numerous, of very various sizes, from many differing localities, Sergestes atlanticus, Milne-Edwards, being found both in the Mediterranean and in the Atlantic from Greenland to the tropics. The account of the genus occu- pies eighty-eight quarto pages and seventeen plates of Spence Bate's ' Report on the Challenger Macrura.' It 222 A HISTORY OF RECENT CRUSTA