VERTEBRATE Z00L03Y Crustacea A TREATISE ON ZOOLOGY t A TREATISE ON ZOOLOGY Demy Svo, Cloth, price 15s. net each; vr in Paper Covers, price 12s. 6d. net each. VOLUMES READY Part I. (First Fascicle) INTRODUCTION AND PROTOZOA. By Sir RAY LANKESTKK, K.G.B., F.R.S. ; Prof. S. J. HICKSON, M.A., F.R.S. ; F. W. GAMBLE, D.Sc, F.R.S. ; A. WILLEY, M.A., D.Sc, F.R.S. ; J. J. LISTER, F.R.S. ; H. M. WOODCOCK, D.SC. ; and the late Prof. WELDOX. Part I. (Second Fascicle) INTRODUCTION AND PROTOZOA. By J. B. FARMER, D.SC., M.A., F.R.S. ; J. .1. LISTER, F.R.S. ; E. A. MINCHIN, M.A. : and S. .1. HICKSON, F.R.S. Part II. THE PORIFERA AND COELENTERA. By Sir RAY LANKESTER, K.C.B., F.R.S.; E. A. MINCHIN, M.A. ; G. HERBERT FOWLER, B.A., Ph.D. : and GILBERT C. BOURNE, M.A. Part III. THE ECHINODERMA. By F. A. BATHER, M.A., assisted by J. W. GREGORY, D.SC, and E. S. GOODRICH, M.A. ^^ Part IV. THE PLATYHELMIA, THE MESOZOA, and THE NEMERTINI. By Prof. BENHAM, D.SC. Part V. MOLLUSCA. By Dr. PAUL PELSENEER. Part VII. APPENDICULATA (Third Fascicle: CRUSTACEA). By W. T. GALMAN, D.SC. Part IX. VERTEBRATA CRANIATA (First Fas= cicle : FISHES). By E. S. GOODRICH, M.A., F.R.S. AGENTS AMERICA . THE MACMILLAN COMPANY 04 & 00 FIFTH AVENUE, NEW YORK AUSTRALASIA THE OXFORD UNIVERSITY PRESS 205 FLINDERS LANE, MELBOURNE CANADA . THE MACMILLAN COMPANY OF CANADA, LTD. 27 RICHMOND STREET WEST, TORONTO INDIA . M'ACMILLAN & COMPANY, LTD. MACMILLAN BUILDING, BOMBAY' 301) Bow BAZAAR STREET, CALCUTTA L \ B n A H Y : DKiil-VJ C? EX-W-Sa A TREATISE ON ZOOLOGY EDITED BY SIR EAY LANKESTEE K.C.B., M.A., LL.D., F.K.S. HONORARY FELLOW OF EXETER UOLLEOE, OXFORD; CORRESPONDENT OK THE IN'STITl'TF. OP TRANCE ; LATE DIRECTOR OK THE NATURAL HISTORY DEPARTMENTS OK THE IiUITISH Ml'SECM PART Yll APPENDICULATA THIRD FASCICLE CRUSTACEA. BY AV. T. CALM AN, D.Sc. ST. AND.) ASSISTANT IN THE ZOOLOGICAL L-EPAKTMKNT "K Till: BRITISH Ml'sr.I'M LOXDOX ADAM AND CHLUtLES BLACK 1909 PREFACE THE present volume is an instalment of that part of the treatise dealing with the great phylum Appendiculata — a phylum which includes the Arthropoda, Chsetopoda, and Hotifera. Jh\ Caiman having finished the present description of the Crustacea, it has been considered advisable to publish it at once, without waiting either for the general intro­ duction on the classification and characters of the phylum Appendiculata or for the completion of the fascicles devoted to tlie Peripatoids, Chilopods, Arachnids, Chilognaths, Hexapod Insects, Choetopods, and Rotifers. E. KAY LANKESTER January I 909. v CONTEXTS CHAPTER I I'ACK THE CLASS CRUSTACEA ..... 1 CHAPTER II THE BRANCHIOPODA ...... 29 CHAPTER III THE OSTRACODA ...... 5(5 CHAPTER IV THE COPEPODA . .71 CHAPTER V THE CIRRIPEDIA . 10G CHAPTER VI THE MALACOSTRACA . 143 CHAPTER VII THE LEPTOSTKACA . .151 CHAPTER VIII THE SYXCARIDA . .162 THE CRUSTACEA CHAPTER IX PAGE THE MYSIDACEA 17J CHAPTER X THE CUMACEA 183 CHAPTER XI THE TANAIDACEA 190 CHAPTER XII THE ISOPODA 15)6 CHAPTER XIII THE AMPHIPODA 224 CHAPTER XIV THE EUPHAUSIACEA 244 CHAPTER XV THE DECAPODA 253 CHAPTER XVI THE STOJIATOPODA 319 INDEX 333 CHAPTER I CLASS CRUSTACEA. SUB-CLASS I. BRANCIIIOPODA. Order 1. Anostraca. „ 2. Notostraca. „ 3. Conchostraca. ,, 4. Cladocera. SUB-CLASS II. OSTRACODA. Order 1. Myodocopa. „ 2. Cladocopa. „ 3. Podocopa. „ 4. Platycopa. SUB-CLASS III. COPEPODA. Order 1. Eucopepoda. „ 2. Branchiura. SUB-CLASS IV. CIRRIPEDIA. Order 1. Thoracica. ,, 2. Acrothoracica. ,, 3. Ascothoracica. ,, 4. Apoda. „ 5. Khizocephala. SUB-CLASS Y. MALACOSTRACA. SERIES A. LEPTOSTRAOA. DIVISION PIIYLLOCARIDA. Order Nebaliacea. SERIES B. EUMALAOOSTRACA. DIVISION 1. SYNCARIDA. Order Anaspidacea. l 2 THE CRUSTACEA DIVISION 2. PEKACARIDA. Order 1. Mysidacea. „ 2. Cumacea. „ 3. Tanaidacea. ,, 4. Isopoda. „ 5. Amphipoda. DIVISION 3. EUCARIDA. Order 1. Euphausiacea. _ „ 2. Decapoda. DIVISION 4. HOPLOCARIDA. Order Stomatopoda. Introductory.—The Crustacea form one of the Classes com­ posing the Sub-Phylum Arthropoda, and include, besides the forms popularly recognised as Crabs, Lobsters, Crayfish, Prawns, Shrimps, Sandhoppers, Woodlice, Barnacles, and Water-fleas, a multitude of related organisms which are nameless in common speech. The Class presents so wide a range of structural diversity that it is all but impossible to give, in a few words, a definition which shall apply to all its members. Of the great majority it may be said that they are Arthropoda of aquatic habits, breathing by gills or by the general surface of the body, having two pairs of antenniform preoral appendages, and having at least three pairs of postoral appendages acting as jaws, the three corresponding somites being coalesced with the head. But while these characters are found in the more primitive members, actual or hypothetical, of all the sub-classes and orders composing the Class, the more modified types furnish exceptions to every statement of the definition. Thus, the land-crabs and woodlice are not only completely terrestrial in their habits, but are provided with special organs for aerial respiration ; the preoral appendages may be modified for locomotor or prehensile functions, or may be quite wanting; and some or all of the mouth- parts may be suppressed. The most extreme modifications are found in parasitic forms, and some of these, snch as the Rhizocephala, have lost, in the adult state, almost every trace, not only of Crustacean, but even of Arthropodous structure. In these cases, however, the larval stages afford indications of affinity, while less specialised forms provide connecting links with the typical Crustacea and leave no doubt as to the natural character of the Class as a whole. Historical.—In the S/jstema Naturae (12th edition, 1767), Linnaeus placed most of the Crustacea then known in his Class Insecta (equivalent to the sub-phylum Arthropoda as now under- THE CRUSTACEA 3 stood), where they formed, with the Arachnida, one of the divisions of the Order Aptera. Three genera were recognised, Cancer, Monoculus, and Oniscus. The Barnacles, however, forming the genus Lepas, were placed among the Vermes testacea, between Chiton and Pholus, and the genus Lemaen, comprising certain parasitic forms, was classed under Vermes mollusca. The adjective crudata or Crustacea had been applied, more or less loosely, by the older naturalists to animals possessing a hard exoskelcton, and Brisson, in 1756, had used it as the designation of a group. Pennant, in 1777, appears to be the first post-Linuaeau author to suggest the separation of a distinct class under the name Crustacea, and this step was definitely taken in Cuvier's Leeons iVAnatomic compare'e (1800), where, however, the Isopoda still remained among the Insects. Lamarck in 1801 included the Isopoda, and Latreilie made many changes in the classification, the most important being the division of the class into Malacostraca and Entomostraca {Genera Crust, et Insect., 1S0G). This arrangement, with the further division of the Malacostraca into Edriophthalma and Podophthalma, proposed by Leach in 1815, has been widely adopted down to the present day. The researches of J. C. Savigny on the structure of the mouth- parts in Insects and Crustacea (1816) laid the foundations of modern conceptions of Arthropod morphology. Among his immediate successors in this line of research, perhaps the most prominent names arc those of V. Andouin and H. Milne-Edwards. The Jfistoire Naturclle des Crust aces of the last-named author (1834-1840) marks an epoch in the history of Carcinology and is still indispens­ able to the student. It is curious that, even at this date, Milne- Edwards did not include the Cirripcdia in his survey of the Crustacea, although J. Vaughan Thompson had already in 1830 described their larval stages and recognised their Crustacean affini­ ties. Apart from this omission, the limits of the Class adopted by Milne-Edwards differ from those now generally accepted in includ­ ing the Pycnogonida, the Xiphosura, and the Trilobita. There can be little doubt that the affinities of these groups are with the Arachnida, though it is possible that the very primitive Trilobites were also phyletically related to the Crustacea. It is impossible to summarise here the numerous changes in classification introduced since the date of Milne-Edwards' work, but it may be mentioned that the establishment of a phylogenctic basis for classification is largely due to the numerous and important works of C. Clans. Further notes on the historical development of the subject will be given in the chapters dealing with the separate sub-classes and orders. 4 THE CRUSTACEA GENERAL MORPHOLOGY. Exoslceleton.—In the Crustacea, as in other Arthropoda, the exo- skeleton of the body consists typically of a series of segments or somites which may be movably articulated or more or less coalesced together. In its simplest form the exoskeletal somite is a ring of chitin, connected with the adjacent rings by areas of thinner integument permitting movement in various directions, and having a pair of appendages attached to its ventral surface. This ring may be further subdivided into a dorsal tcrgite and a ventral dernitc, and the tergite may overhang the attachment of the appendage on each side as a free plate called the plcvron ] (Fig. 1). At the posterior end of the body is a terminal segment known as the telson, upon which the anus opens. This segment never bears typical limbs and its nature has been variously interpreted. It has been regarded as a true somite or A transverse section of one of the rpcnlHmr from HIP pmlpqrpnrp abdominal somites of the Crayfish (Asttu-us). aS IGSUlUllg irom Uie Coalescence a, appendage ; V, pleuron ; s, sternite ; /, 0f a number of SOmiteS, while S0111C tergite.