8v Wi * ^3 ■-^ ; ;;;,.;"«>► INDIAN MUSEUM. PART I. BRACHYURA. FASCICULUS I. INTRODUCTION AND DROMIDES OR DROMIACEA (BRACHYURA PRIMIGENIA). BY A. ALCOCK, M.B.. LL.D., F.R.S. ■ • 1 INDIAN MEDICAL SEKVICE, COKRESPONDING MEMBER OK THE ZOOLOGICAL SOCIETY, FELLOW OF THE GEOLOGICAL SOCIEXr. SUFEIUNTENDENT OP THE INDIAN MUSEUM AND PROFESSOR OP ZOOLOGY AND COMPARATITE ANATOMY IN THE MEDICAL COLLEGE, CALCUTTA. SOMETIME SUKOEON-NATURALIST \ TO THE INDIAN MARINE SURVEIT. m »-^/ii ^^^K =.V./^ \.>S©-/ 4:V.V70O CALCUTTA PRINTED BV URDKR OF TIIK IRUSTKHS OF THF INDIAN IMUSEUM. 1901. y4< CATALOGUE OF TlfK INDIAN DECAPOD CliUSTACEA IX THE COLLECTION OF THE INDIAN MUSEUM. PART I. BRACHYURA. FASCICULUS I. INTRODUCTION AND DROMIDES OH DROMIACEA (BRACHYURA FRIMIGBNIA). BY A. ALCOCK, M.B.. LL.D., F.R.S. INDIAN MKIilCAL SRKVICE, COIiRESPONDING MEMBER OF THE ZOOLOGICAI, SOCIETY, FELLOW dV THE i; tUI.DIilc'Al, SOrlECV. SUPICRINTENDENT OF THE INDIAN MUSEDM AND PUOFESSOR OF ZOOLOGY AND COMPAnATIVE ANATOMY IN THE MEDICAL COLLEGE, CALCL'ITA. SOMETIME SUItGEON-NA M' 1,'A 1 I ST rO THE INlilAX -MAI.'INE smVKV. 2S^»^J eb-j^-^^'j^^ CALCUTTA: PKIXIED BV URUKR UF TIIK TKUSrEKS OF I'llK INDIAN MUSKU.M. 1901. Price Seven Rupees. CONTENTS OP PART I FASCICULUS T. Index of Authors Quoted ... InTRODDCTION : — Morpliology of tlie Deoapoda Classification of the Decapoda ... Brachyora: — General Considerations Classification of tlie Bracliyura ... Dromides or Dromiacea ... Droroiidea Homolidea Table of the Genera and Species of Recent Dromiacea pp. v-ix. pp. -2-12. jip. l:{— 1.5. ]i|i. 1(3—25. pp. 26—28. pp. 28—29. pp. 29—58. pp. 58—73. pp. 74—80. Phefack. The Catalogue of [udian Decapod Crustacea, of which this is the first instal- ment, occnpied in its early preparatory stages inucli of the attention of my predecessor Mr. James Wood-Mason, and has in execution taken up the greater jiart of my own time, particularly in leisure honrs, during the last eight years. At the outset T looked foi'ward to signalizing on the title-page my late frientl's connexion with this undertaking; but 1 now Hnd it necessary to take the entire responsibility of the work as it stands, and to state that the idea of codifying oin- knowledge of Indian carcinology originated many years ago Avith Wood-Mason, and that by collecting and commencing to index all the classical literature of the subject, by sorting into great-groups that part of the Museum collection of Ci'ustacea tliat was made independently of the Survey Ship " Investigator," by gradually ac(|uiring a considerable nnnil)er of authentically-named species of Crustacea, and by provisionally naming a good uiany Tndo-Pacific species himself, Wood-Mason had gone no inconsiderable way towards eariying his idea into effect. It is pi-0]»osed to issue the ('ataloguc in three collateral and iiulependent series, one for the llraehijiira, anotluM' for the Marriiru, :ind a third for the AitoTihiira. — I iisr THE INDIAN MUSEUM A. Ai.cocK, Major, I.M.S., Sn'iierinh'ndcnt of tlir Indian Mhschih. INDEX OF THE WORKS QUOTED IN THIS VOLUME. 1. AnAMS, A. and White, A. — Zoology of the Voyage of H.M.S, Samarang, Crustacea. London, 1850. tl. Alcock, a. — Natural History Notes from the Royal Indian Marine Survey Ship " Inve.stigator." Series II, No. 1. Annals and Magazine of Natural History, May, 1894. 3. ,, ,, Materials for a Carcinological Fauna of India. No. .5. The Brachyura Priniigenia, or Dromiacea. Jo%irnul of the Asiatic Society of Bengal, Vol. LXVIII, Pt. 2, 1899. 4. ,, ,, An Account of the Deep Sea Brachyura collected by the Royal Indian Marine Survey Ship " Investigator." Calcutta, 1899. 5. Alcock, A. and Anderson, A. R, S. — Natural History Notes from the Royal Indian Marine Survey Ship " Investigator." Series II, No. ll. Jotirnal of the Asiatic Society of Bengal, Vol. LXIII, Pt. 2, 1891. 6. „ ,, Do. Do. Series III, No. 2. Annals and Magazine of Natural History, January, 1899. 7. Bate, C. Spence. — Report on the Crustacea Macrura collected by H.JI.S. Challenger. London, 1888. 8. Bei.l, T. — A History of the British Stalk-eyed Crustacea. London, 1853. 9. BoA.s, J. E. V. — Studier over Decapodernes Slaegtskabsforhold, avec ua resume eu francais. Danske Videnskab. Selskab Skrivter, 6 Eiekke, luiturviden- skahelig og mathematisk Ajd. I, 2, 1880. 10. BonuAPAll.E, L. A. — Crustaceans from the South Pacific. Part IV, Crabs. Proceedings of the Zoological Society of Loudon, for 1900. 11. Bosc, L. A. G. — Histoire Naturelle des Crustaces. Paris, 1803. 12. BouviEi;, E, L. — Sur rorigine Homarienne des Crabes. Bulletin de la Societe Pliiloma- thique de Paris: ser. 8, torn. VIII, 1895-yG. 13. ,, ,, Crustaces Anomoures et Brachyures recuellis en Basse Califoruie. Bulletin die Miiseurr,. d'Hlstoire Naturelle. Paris, 1898. 1-1. Buoccul— Sur les organes genitaux males des Crustaces Decapodes. Annates des Sciences Naturelles, ser. 6, torn. II, 1875. Zoologie. 15. Cano, G. — Viaggio della R. Corvetta Vettor Pisaui attorno al Globo. Crostacei Brachiuri ed Anomouri. Boll. Soc. Nat. Napoli, III, 1889. hj. Cakbington, J .T. and LovETT, E. — Notes ou British Stalk-eyed Crustacea. The Zoologist : ser, :;, Vol. VI, 1882. 17. Cakcs, J. V. — Prodronuis Fauna; Mediterranean. Vol. I. Stuttgart, 1885, VI 18. Clads, C. — Untersucliuniien zur Erforscliuiifj tier gpnealogisclicn Grundlage des Crus- taceensystems. Vienna, 1876. 19. „ Grundziige der Zoologie, 4tli Edit. Waibuig, 1880. 20. Costa, 0. G.— Fauna del Regno di Napoli— Naples, 1836-1870. Crostacei. 21. Dana, J. D. — United States Exploring Expedition. Vol. XIII, Crustacea, pait I. Philadelphia, 1852. 22. De Br^BISSON. — Catalogue des Crustaces du Calvados. Memoires de la Societe Liuneenne du Calvados. 1825, Caen et Paris. 23. De Haan, W. — Fauna Japonica, auctoie P. F. De Siebold, Crustacea. Leyden, 183.5- 185C. 24. De Man, J. G. — Ueber die im indischeu Archipel gesammelten Decapoden. A-rchic fiir Naturgeschichte, Jahrgang LIII, Bd. i. 1887. Berlin. 23. ■„ Report on the Podoplitlialmous Crustacea of the Mer^ui Archipelago. Journal of the Linneaii Society, Zoology. Vol. XXII, 1887-1 888. 26. ,, Ueber neue order seltene iudopacifiselie Brachyuveii. Zoologische JaJirbiicher. Ahtheiluny fiir Systematik, etc. Bd. IV, 1889. 27. „ Decapoden uud Stomapoden von Malakka, Borneo, und Celebes. Zooloyische Jahrbiccher. Ahtheilmuj fiir Systematik, etc. Bd. IX, 1897. 28. Desmarest, a. G. — Article Malacostraca in Dictionnaire des Sciences Naturelles. Tom. XXVIII, 1823. Paris. 29. ,, Considerations Generales sur la Classe des Crustaces. Paris, 182.5. 30. Eydoux et Sodleyet. — Voyage autour du Monde sur la corvette La Bonite. Zoologie, torn. I. Paris, 1841. 31. Pabricius, J. C. — Entomologia Systematica (et Supplementum). Copenhagen, 1792- 1798. 32. Gerstaecker, A. — Bronn's Klassen und Ordnungen des Thier-Reichs. Crustacea Malacostraca. 33. Gray, J. E. — The Zoological Miscellany. London, 1831. 34. GuiRiN-MtNEViLLE, F. E. — Iconographie du Regue Animal du Cuvier. Paris, 1829- 1844. Crustaces. S5. ,, Description du genre Hypoconcha. Jieviie et Magasin du Zoologie : ser. 2, tom. VI. 18.54. Paris. ~i6. GuiLDIKG, L. — An Account of some rare West-Indian Crustacea. Transactions of the Linnean Society of London. Vol. XIV, 1825. 37. Hasweli., W. A. — Description of some New Specie.s of Australian Decapoda. Proceed- ings of the Linnean Society of New South Wales. Vol. VI, 1882. ;i8. „ Catalogue of the Australian Stalk- and Sessile-eyed Crustacea. Sydney, 1882. 39. Hei.leb, C. — Crustaceen-Fauna des rothen Meeres. SitzmigshericMe der Mathematisch. Naturivissenschafllichen Classe der K. Akademie, Wien. Bd. XLIV. Abth. 1, 1862. 40. „ Die Crust aceen des siidlichen Europa. Vienna, 1863. 41. „ Reise der Oesterreichi.schen Frigate Novara uni die Erde. Crustaceen Viennii, 1865. Vll 42. Hendeusos, J. R. — Report on tlie Aiioniiira collected by H.M.S. Challenger. Loudon- 1888. 43. ,, A Contribution to Indian Carcinolog-y. Transactions of the Liiincau Society of London. Zoology, ser 2, Vol. V, 1893. 4^. Hehbst, J. F. W. — Ver.such einer Naturgeschiclite der Fvtjibben und Krebse. Berlin, 1790-1804. 45. HiLGENDORF, F. — Mozambique Crustaceen. Moudtsherichte der K. Preiissischen Akademie der Wissenschaften zu Berlin, 1879. 46. HnxLEY, T. H. — On tbe Clas.sification and the Distribution of the Crayfishes. Proceed- ings of the Zoological Society of London, 1 878. 47. „ The Crayfish. London, 1880. 48. Ilh:str.\tions of the Zoology of the Rotal Iniuan ^Iarine Sdrvey Ship " Investi- gator." Calcutta, 1892-1900. 49. Ives, J. E. — Echiuoderms and Arthropods from Japan. Proceedings of the Academy of Natural Sciences of Philadelphia. 1891 (1892). .50. KiNGSLEY, J. S. — On Crustacea from Virginia, North Carolina, and Florida. Proceed- ings of the Academy of Natural Sciences of Philadelphia, 1879 ( 1880). .jl. KossMANN, R. — Zoologisehe Ergebnisse einer Reise in die Kiistangebiete des rotheu jNIeeres. Malacostraca. Leipzig, 1877. 52. „ Kurze Notizen iiber ncue Crustacccn. Archie fiir Natiirgeschichte, -Jahr- gang, XLIV. Bd. i., 1878, 53. Kradss, F. — Die siidafi-ikaniscUen Cr-ustaceen. Stuttgart, 1843. 54. Lamarck, J. B. P. A. — Histoire Xaturelle des Animaux sans Vertebres. Paris, 1815- 1822. 55. Lati;eille, P. A. — Histoire Xnturelle des Crustace.s et des Insectes. Vols. V-VI. Paris, 1803. 66. ,, Geneiu Crustacfonini et Insectorum. Paris, 1806. 57. ,, Articles in Nouveau Dictionnaiie d'Histoire Naturelle. Tom. IX. Paris, 1817. 68. Lea.ii, W. E.— The Zoological Miscellany. London, 1814-1817. 59. ,, A Tabular view of the characters of the Insecta, etc. Trancactiins of the Linnean Society. Vol. XI, 1S15. 60. ,, Malacostraca Podophthalmia Britannia". Loudon, 1815. 61. LiNNfi, C. — Systema Naturas, torn. 1. pars. ii. Editio Duodecima Reformata. Stock- holm, 1767. 62. Lucas, H. — Exploration Scientiiique de TAlgerie. Histoiro Naturello dc3 Auimaus Arti- cules. Part I. Paris, 1849. 63. „ Histoire Naturelle des Crustaces, des Arachnldes, et des Myriapodcs. Paris, 18.J0. 64. Maci.eay, W. S. — Illustratious of the Aunulosa of South Africa. London, 1838. 65. MiERS, E. J. — Catalogue of the Stalk- and Sessile-eyed Crustacea of Ne\T Zealand. London, 1876. 66. „ On Crustacea from the Corean and .lapauesp. Seas. Proceedings of the Zoological Society of London, 1879. vni f>~. MiERS, E. J. — On Crustacea from tlie Malaysian Region. Ammh and Magazine of Natural History, ser. 5, Vol. V, 1880. 68. „ Crustacea from Goi'ee Island, Senegarabia. Annals and Magazine of Natural History, ser. 5. Vol. VIII, 1881. 69. „ Ou Some Crustaceans from Mauritius. Proceedings of the Zoological Society of London, ]884. 70. „ Eeport on the Zoological Collections made in the Indo-Pacific Ocean during the voyage of H.M.S. Alert. Crustacea. London, 1884. 71. „ Report on the Bracbyura collected by H.M.S. Challenger. London, 1886. 72. Milne Edwards, A. — Crustacea nouveaux provenant des Voyages a Zanzibar et a Mada- gascar. Nouvelles Archives da Museum d'Histoire Naturelle de Paris. Tom. IV, 1868. 78. „ Memoire siir les Crustaces Decapodes du genre Dynomeue. Annales des Sciences Naturelles. Zoologie. Ser. 6, Tom. VIII, 1879. 74. „ Reports on tlie Results of Dredging by the United States Coast Survey Steamer Blake. Bulletin of the M-iiseum of Comparative Zoology at Harvard College in Cambridge. Vol. VIII, ISSO-Sl. 75. „ Recueil de Figures de Crustaces nouveaux ou peu counus. Paris, 1883. 70. Milne Edwaei-s, A. et BiuviEi;, E. L. — Crustaces Decapodes provenant des campagnes du yacht I'Hirou- delle. Part. I. Brachyures et Anomoures. Monaco, 1894. 77. ,, Cru.staces Decapodes piovenaut des campagnes de I'Hirondelle (Sup- pU'inent) et de la Princesse Alice. Monaco, 1899. 78. „ Expeditions Scientifiques du Travailleur et du Talisman. Crustaces Decapodes: part I. Brachyures et Anomoures. Paris, 1900. 79. Milne Edwaiids, H. — Histoire Naturelle des Crustaces. Paris, 1834-1840. SO. „ La Regne Animal par Georges Cuvier. Les Crustaces. Paris. 81. MiJLLER, F. — Zur Crustuceenfauna von Trincomali. Verhandlungen der Naturforschenden Gesellesrhaff in TiaseL Till, 18S6. 82. Ortmann, a. — Die Decapodeiikreb.se des Strassburger Museums. ZoologischeJakrbucher. Ahtheilnng fiir Systematik, etc. Bd. VI, 1892. 83. „ Crustnceen in Semon Zoologische Forschungs-reisen in Australien und dem Malayischen Ai-chipel. Jenaische Denhschriften. VIII, 1895. 84. ,, Malacostraca, in Bronn's Klassen und Ordnungen des Thier-Reichs. 8.5. Peters, W. — Ueber das System der Dekapodeu. Monntsherichte der K. Preussischeu Ahademie der Wissenschaften zu Berlin, 1861 (1862), p. 717. 86. Rathbun, Makt J. — Decapod Crustacea of Jamaica. Annals of the Institute of Jamaica. Vol. I, 1897. 87. ,, Decapod Crustaceans of West Africa. Proceedings of the United States National Museum.. Vol. XXII, 1900, 88. RiCHTEKs, F.— Meeresfauna der Insel Mauritius und der Seychellen. Decapoda. Berlin, 1880. 89. Risso, A. — Histoire Naturelle des Crustacea des environs de Nice. — Paris, 1816. 90. ,, Histoire Naturelle des Principales Productions do I'Europo Meridionale, etc. Paris, 1826. 1*1 Riiix. P.— Crustaces de la Mediterraneo et de son littoral. Paris, 1828. 02. RcMPHiUiS, G. E. — D'Amboinsche Rariteitkamer, eti3. Amsterdam, 1705. 93. RuPPELL, E. — Beschreibung und Abbildung von 2i Arten kurzschwiinzigen Krabbeii des rothen Meeres. Frankfurt, a. M., 1830. 'J4t. Sep.a, a. — Thesaurus Rerum Naturalium. Amstei'dam, i7i>8. 9-5. Smith, S. J. — Preliminary Report on the BracLyura and Anomura dredged in deep water off the south coast of Now England. Proceedings nf the United States National Museum for 1883, Vol. VI. 96. „ Reports on the Decapod Crustacea of the Albatross Uredgings. Aninutl B'eports of the United States Commissioner of Fish and Fisheries fur 1882 (188-1) and 1885 (1886). 97. STE:;i;i.\ti, T. R. R. — A History of Crustacea. Recent Malacostraca. London, 1893. 9g. „ ., ilarine Investigations in South Afiica, Crustacea. Cape Town, 1900. 99. SiiMPtioN, W. — Prodronious descriptionis Animaliuni evertebratorunr, etc. rruceedimjs of the Academij of Natural Scienas of Philadelphia, 1858 (1859). 100. „ Notes on North American Crustacea in the Museum of the Smithsonian Institution. Annals of the Lijceuni of Natural History of New . York, Vol. VII, 1862. 101. Studeu, T. — Crustaceen der Gazelle von Westafrika. Ahhandlungen der Koniglichen Akademie der Wissenscluijtvu :u Berlin, 1882 (1883). 102. Thomson, G. M. — A Revision of the Crustacea Anomura of New Zealand. Transactions and Proceedings of the Neu- Zealand Institute, 1898 (1899). 103. To/./.ETTi, A. T. — Zoologia del Viaggio Intorno al Globo della R. Pirocorvetta ilagenta. Crostacei Brachiuri 0 Anomouri. Florence, 1877. 104. Veurili,, a. E.— On the parasitic habits of Crustacea, llie American Naturalist, Vol. Ill, iy70. lO.j. W.4LKEI!, A. 0. — On Crustacea from Singapore. Journal of the Linncan Sociclg, Zoologg. Vol. XX, 1886-1900. 106. "White, A. — List of the specimens of British Animals in the collection of the British Museum. Part IV, Crustacea. London, 1850. 1U7. WnnELEflGE, T. — The Crustacea of Funafuti. Memoir III. Australian Museum, Sydney, 1897. 108. „ Scientific Results of the Trawling expedition of H.M.C.S. Thetis, Crustacea. Memoir IV. Australian Mttse^^m, S'/dnei/, 1900. 109. WooD-M-\soN, J. — Natural History Notes from the Royal Indian ilarine Survey Ship ■' Investio-ator." No. 21. Anmils and Magazine of Natural History. March, 1891. 110. ZiETz, A. — New species of Austialian Crustaceans. Transactions aiul Proceedings of the Foyal Society if South Australia, Vol, X, 18S6-I887. IXTRODUCTION. This volume is the First Part of a monograph of the Decapod Crustacea of that part of the Oriental Eegion of Wallace which Kes within the political boundaries of British India. The Decapoda belong to the subclass Malacosfraca of the Crustacean kind, the Crustacea being one of the main branches of the great phylum Arthropoda. In the members of this phylum, which also includes the Xipliosura, the Arachiida, the Millipedes, the Centipedes, and the Insects, the body consists of a series of segments or somites carrying jointed or segmented appendages. Though the segments — with the pair of appendages which each one typically carries — may vary greatly in actual form, yet they are all built on one and the same fundamental plan, and the superficial layers of the integument, both of the somites and of the appendages, are more or less completely hardened, by chitin or by salts of lime, so as to form a rigid exoskeleton, which during growth is periodically moulted. Among the Arthropoda the Crustacea are recognized by the fact that while they possess antennae, as do the air-breathing Insects, Centipedes and MilUpedes, they typically breathe in water by means of gills connected with the appendages, as do the non-antennate king-crabs {Xiphosura) . Their spermatozoa are non- motile, like those of Millipedes. Among the Crustacea the Malacostraca are distinguished by the fact that the body is made up of a definite and constant number of segments. The characters that separate the Order Becapoda from the other ordei's of Malacostraca will be understood if we examine, in some detail, a typical member of the Order. The type usually selected is the European Crayfish, Astacus fluviatilis : the type here chosen is the Andaman Lobster, Nephrops andamanica, as belonging to the local fauna. As far as tbe general construction of the body, the general modifications of its appendages, and the general relations of the viscera go, any of the common species of freshwater or murine prawns (Palsemon, Feneus) may be used for dissection if Nejihrops is not procurable. I. MOEPHOLOGT OF NePHEOPS ANDAMANICA. 1. Of the general construction and segmentation of the Body. In a typical Decapod Crustacean, such as Nephrops andamanica, the body is elongate and is manifestly divided into two regions, an anterior region or cephalothorax and a posterior region or abdomen, of which the latter is the longer. The cephalothorax is covered, as to its back and sides, by a shield or carapace, so that its segmentation — or subdivision into somites — is not immediately apparent ; but the abdomen obviously consists of a series of seven segments, and therefore bespeaks our attention first. Any one of the seven freely-movable abdominal somites, except the last, is seen to be a ring, with a pair of appendages attached to its under surface. The dorsal arc of the ring is wide fore-and-aft and is known as the tergmn, the ventral arc is narrow fore-and-aft and is known as the sternum, while the over- lapping sides of the ring are called the plexira : furthermore, the narrow corner between the articulation of the appendage and the pleurum of either side is termed the epimerum. On turning to the cephalothorax, the most that we can distinguish, before the removal of the carapace, are the narrow sterna of some of the thoracic somites ; and even when we have removed the carapace, and have cleared away the gills that lie beneath it, we shall at first sight find, instead of the succession of rings that the abdomen shows, merely the greatly-extended epimera of some of the thoracic somites. The cephalothorax is, however, as an examination of its sterna and append- ages reveals, made up of 14 segments, all of which are immovably fused together, many of which are contracted and foreshortened and obscured, and none of which — with the exceptions presently to be noticed — possess identifiable terga like those of the abdomen. The place of terga and pleura is taken by the carapace, the main dorsal mass of which is generally supposed — though it is not certain that this explanation covers all the facts — to be an enormous extension backwards of those elements of the 3rd (antennal) and 4th (mandibular) somites of the body. The carapace, it is to be observed, does not merely serve as a cover to the united segments of the cephalothorax, but it overlaps those segments so as to enclose on either side of them a space in which the gill-plumes he, this space being known as the branchial chamber. Moreovei-, it is produced forwards in the middle line, to form a stout bayonet-like organ of defence — the rostrum. Although the cephalothorax is one composite whole, it consists of two ill- defined regions, an anterior cephalic region or head and a posterior region or thorax. The boundary line between the two regions is marked on the carapace by a deep semicircular groove — the cervical groove ; and when the carapace is removed, the division between the two regions is still obscurely indicated by a fold or a pair of lateral hollows in which a pair of organs known as scapliorinatliites (to be described along with the appendages) lie. We shall find, on examining the appendages, that the head consists of six segments fused together, and the thorax of eight. Add to these the seven abdominal segments, and we get twenty-one as the number of segments that make up the body of Nephrons. It has been questioned wlietlier the last segment of the abdomen, known as the telson, is really a somite, since among other reasons it carries no appendages. But it seems probable, from the form and sculpture of this part of the body in certain deep-sea Decapods— notably the J? rf/o)U(f« and some GalatheiJse — that the telson consists of a modified somite and a pair of biramous appeud- iiges all fused together. Moreover it is traversed by the intestine. It has also been objected that the eyes are not truly homulogous with appendages and that the part from which they spring is not therefore a somite. But apart from other considei-ations tlie fact that, as a "substitution" abnormality, the' eyestalk may be replaced by a recognizable appendage, is enough to dispose of this objection. On the other hand it has been argued that the pair of fleshy lobes that form the posterior boundary of the mouth-slit and are known as the metastoma or loiver lip, .are true appendages and therefore represent an additional somite ; though there are no facts to support this view. The cephalothorax is held together not merely by fusion of the sterna and epimera of its constituent somites, but also by an internal lattice-work of thin hard obliquely-transverse partitions known as apodemes. Although the apodemes are internal and serve to protect and support the viscera as well as to give attachment to muscles, they are merely infoldings of the cuticle of the constituent sterna and epimera. They are only found behind the mouth and in the ventral half of the somites. Before further considering the segmentation of the cephalothorax it is necessary to speak of the appendages. 2. Of t]te Appendages in general. The recognizable appendages of Nephrops andamanica are twenty pairs. The first six pairs belong to the head : three of them lie in front of the mouth and are organs of the senses, while three are crowded together on either side of the mouth and are biting and chewing organs, the last pair also contributing to the respiratory mechanism. The next eight pairs belong to the thorax : the first three of them, which are crowded together in close succession to the mouth-parts of the head, ari> organs partly of manducation and partly auxiliary to respiration ; while the other five are legs in the ordinary sense, though some of them are modified for prehension, and most of them take a certain part in respiration. It is from these 5 pairs of large legs that the name of the Order is derived. The last six pairs belong to the abdomen and are primarily swimming- paddles, some of which, in the male, are modified to subserve reproduction, and in the female subserve nutrication or the care of the developing embryo. Just as the abdomen furnishes the type of the unmodified Crustacean seg- ment, so also it gives us the type of the Crustacean appendage. An appendage taken from, say, the 3rd abdominal somite consists of a stalk, or protopodite, to the end of which two leaf -like branches are articulated, the inner branch being known as the endopodite the outer as the exopodite. The stalk itself consists of two segments, a short basal piece or coxopodite, by means of which it is articulated to the somite, followed by a larger sub-cylindrical hasipodite'. Although a minority of the appendages of a Decapod Crustacean exactly con- form to this description, yet they all can be referred to this general plan, or type. 3. Of the Segments and Appendages of the Head. The first segment, or ophthalmic somite, is hidden by its appendages, the eyes. If the eyes are pushed aside, we shall find, between and just below them, a small plate of leathery consistence : this is the sternum of the ophthal- mic somite, and is all that we can with safety recognize as belonging to that somite. Its appendages, the eyestaJks, each consist of a simple two-jointed pro- topodite, the large compound facetted eye terminating and forming the chief part of the second joint. The second segment, or antenmdar somite, is also a good deal hidden. All that we can recognize as certainly belonging to it is its sternum, which is a narrow partition between the antennules ; but the " orbits," or facets on either side of the carapace on which the eyes rest, are very probably its epimera. Its appendages are the antennules, each of which consists of a thickish stem or peduncle (protopodite) to the end of which two long slender t&:^eYmg flagella (exopodite and endopodite) are articulated. The protopodite is abnormal in consisting of three segments : the proximal segment contains the avditori/ sac, the small orifice of which is seen at the inner border of the upper surface of the segment, in its posterior half. The flagella consist of a series of little rings with fine setae : the outer, or olfactory flagellum, is the thicker of the two, and its setae are larger and more thick-set, especially in its distal part. The third segment is the antennal somite and its appendages are the antennse. The broad space between the bases of the antennte, known as the epistome, is the sternum of this somite, behind the outer ends of which the epimera are visible. The pleura and the tergum of this somite probably form all that part of the carapace that lies in front of the cervical groove. Perhaps it would be better to say tbat, whatever other elements maj- enter into the formation of that part of the carapace which lies in front of the cervical groove, the pleura and terga of the third or antenuular somite can, in many Macrarous and Braohyurous Crustacea, be recownizod as forming the preponderating element. Each antenna consists of a peduncle, a scale (exopodite), and a lash or fiagellum (endopodite). The peduncle is constituted of a rather zig-zag series of five joints, the first two of which correspond with a protopodite : on the ventral surface of the first joint is a prominent orifice, the renal tubercle, at which the green gland, or excretory organ, opens. The antenna! scale, which is a broad thin plate, is articulated to the end of the 2nd joint of the peduncle. The fiagellum, which is slender and of great length, is made up of a succession of little rings, and articulates with the end of the peduncle : it is an organ of touch. The fourth segment is the mandibular somite and its appendages are the viandihles : its modifications take the same turn as do those of the antennal somite. Its sternum is recognizable as forming the posterior part of the epistome ; its pleura and tergum probably constitute the preponderating elements of that part of the carapace which lies behind the cervical groove. It is difficult to avoid the inference that in the carapace of most Macrura and Bracltyura the part whicli lies behind the cervical groove belongs to the mandibular somite. In most Anoviura, however, and in some Macrura, the mandibular soniite seems to enter into the formation of the sidewalls of the carapace only. Furthermore, the sutures of the carapace of Thalasdna forcibly suggest that other terga and pleura, besides those of the antennal and mandi- bular somites, may take a considerable share iu the formation of both the roof and the sidewalls of the carapace. Each mandible consists of (1) a strongly calcified protopodite placed obliquely, and (2) a cm"ved three-jointed palp (eiidopodite). The body of the mandible, or protopodite, is shaped something like a tooth : its distal end is broadened and is grooved fore-and-aft, the ventral edge of the groove forming a salient and trenchant incisor process, while the concealed dorsal edge of the groove forms a broadened molar process. The fifth and sixth segments are only visible after the anterior appendages of the thorax ai'e removed, and even then all that is seen of them is a little plate lying in the middle line, behind the mouth, and representing their conjoint sterna, to which they are reduced. It is also possible that their pleura are represented — though their individuality is, of course, completely lost — by a part of the edge of the carapace in their own immediate neighbourhood. Both these somites are, however, represented by appendages. The appendages of the fifth somite are the \st maxillx! They are thin foliaceous chewing-organs, and lie in contact with the mandibles. Each consists of (1) a leaf-like coxopodite and basipoditc, both of which have their long axis nearly transverse and their free (distal) end fringed with set«, and (2) a two- jointed endopodite or palp. The exopodite is not present. The appendages of the sixtli somite are the 2iid maxillse. All their parts are thin and foliaceous. The coxopodite and basipodite resemble those of the 1st maxillge, except that each is deeply cleft into two lobes. There is a tapering endopodite, and a leaf-like exopodite, which last, being used to bale out the branchial chamber in the course of respiration, goes by the special name of scaphognathitn. 4. Of the Segments and Appendages of the Thora,r. The individuality of all eight thoracic somites is maintained by the sterna, which can be seen without removal of the carapace, and by the epimera which can only be seen after the carapace is removed. The individuality of their pleura and terga is entirely lost, but it is possible that the slightly-raised lateral and posterior borders of the carapace represent these elements. We need, therefore, consider in detail only the appendages. The fate of the terga and pleura of the thoracic somites has ahead}' been incidentally con- sidered in dealing with the composition of the carapace. I have adopted with slight modification the views of Milne Edwards I., that the carapace is formed by the terga and pleura of the aptenno-mandibular somites, and that these elements of the thoracic somites are practically unrepresented in the carapace. It must be admitted however that the sculpturing and sutures of the carapace admit of other equally reasonable interpretations. For instance, Huxley {The Crayjlah, p. 166) taught that that part of the carapace which lies in front of the cervical groove represents the terga and pleura of the head ; while of that part which lies behind the cervical groove, the median region represents the terga, and the lateral regions represent the pleura, of the thoracic somites. The sutures of the carapace of Thalassina certainly support this interpretation, and even in the carapace of Nephrops there are grooves and spines which hiirmonize with it. The first pair of thoracic appendages are the 1st maxillipeds. They consist of a protopodite, endopodite and exopodite, with, in addition, a leaf -like appendix having the same function as the scaphognathite and known as an epipodite. The protopodite is formed of a leaf-like coxopodite and basipodite similar to, only larger than, the same elements of the 1st maxillte : the endopodite is a thin two- jointed leaf ; the exopodite, which is longer and slenderer than the endopodite, ends in a truncated y?a(7e//«