SYNOPSIS OF ANIMAL CLASSIFICATION 
 
 Dr. Emil Selenka 
 
 and 
 I. R. Ainsworth Davis 
 
OF THE 
 UNIVERSITY 
 OF 
 
A ZOOLOGICAL POCKET-BOOK : 
 
 OR, 
 
 SYNOPSIS OF ANIMAL CLASSIFICATION. 
 
WORKS BY J. R. AINSWORTH DAVIS, B.A., 
 
 Lecturer on Biology at the University College of Wales, Aberystwyth. 
 In Large Crown 8vo, Handsome Cloth, 12s. 6d. 
 
 BIOLOGY (An Introduction to), 
 
 For the Use of Students. 
 
 Comprising Vegetable and Animal Morphology and Physiology. 
 
 GENERAL CONTENTS. 
 
 PART I. VEGETABLE MORPHOLOGY AND PHYSIOLOGY : Fungi ; Algse ; The Moss ; The 
 
 Fern ; Gymnosperms ; Angiosperms. 
 
 Comparative Vegetable Morphology and Physiology ; Classification of Plants. 
 PART II. -ANIMAL MORPHOLOGY AND PHYSIOLOGY : Protozoa ; Ccelenterata ; Vermes ; 
 
 Arthropoda ; Mollusca ; Amphibia ; Ayes ; Mammalia. 
 Comparative Animal Morphology and Physiology ; Classification of Animals. 
 With Bibliography, Examination Questions, Complete Glossary, and 158 Illustrations. 
 'The volume is literally PACKED with information.' Glasgow Medical Journal. 
 As a general work of reference, Mr Davis's Manual will be highly serviceable to amateur 
 or professional scientists.' British Medical Journal. 
 
 Extra Crown 8vo, with very Numerous Illustrations, Cloth, 3s. 6d. 
 
 THE FLOWERING PLANT : First Principles of Botany. 
 
 Specially adapted to the Requirements of Students preparing for London 
 University Matriculation, Science and Art, and other Examinations. 
 
 ' SUPPLIES A WANT felt by teachers. Mr Davis's method is peculiarly suitable to be- 
 ginners.' The Lancet. 
 
 ' Calculated to be of much service in making clear to fresh minds the framework of 
 botanical science. Chemist and Druggist. 
 
 L \* .Recommended by the National Home-Reading Union, and for Use in the 
 University Correspondence Classes. 
 
 WORKS BY WILLIAM STIRLING, M.D., Sc.D., 
 
 Professor in the Victoria University ; Brackenbury Professor of Physiology and Histology 
 in the Owens College, Manchester; Examiner in the Universities of Oxford and 
 Cambridge. 
 
 In Extra Crown 8vo, with 344 Illustrations, 12s. 6d. 
 
 PRACTICAL HISTOLOGY (Outlines of). 
 
 *** Dr Stirling's ' Outlines of Practical Histology ' is a compact Handbook for Students, 
 providing a COMPLETE LABORATORY COURSE, in which almost every exercise is accom- 
 panied by a Drawing. 
 
 'The general plan of the work is ADMIRABLE. . . . It is very evident that the 
 suggestions given are the outcome of a PROLONGED EXPERIENCE in teaching Practical 
 Histology, combined with a REMARKABLE JUDGMENT in the selection of methods.' 
 British Medical Journal. 
 
 In Extra Crown 8vo, with 234 Illustrations. 
 
 PRACTICAL PHYSIOLOGY (Outlines of). 
 
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 \* A Handbook for the Physiological Laboratory, including Chemical and Experimental 
 Physiology, with reference to PRACTICAL MEDICINE. 
 
 ' Thoroughly well done, and forms an admirable epitome of Physiological Science. . . . 
 An EXCELLENT TREATISE, which we can thoroughly recommend.' The Lancet. 
 
 LONDON : CHARLES GRIFFIN & COMPANY. 
 
A ZOOLOGICAL POCKET-BOOK : 
 
 OK, 
 
 SYNOPSIS OF AMMAL CLASSIFICATION. 
 
 COMPRISING DEFINITIONS OF THE PHYLA, 
 
 CLASSES, AND ORDERS, 
 WITH EXPLANATORY REMARKS AND TABLES. 
 
 BY 
 
 DR EMIL SELENKA, 
 
 PROFESSOR OF ZOOLOGY IN THE UNIVERSITY OF E1ILANGEN. 
 
 TRANSLATED FROM THE THIRD GERMAN EDITION 
 
 BY 
 
 J. R AINSWORTH DAVIS, B.A., 
 
 TRIN. COLL. CAMB. 
 
 LECTURER ON BIOLOGY AND GEOLOGY, UNIVERSITY COLLEGE, ABERYSTWYTII ; AUTIIOR OF 
 "A TEXT-BOOK OF BIOLOGY," ETC. 
 
 Interleaved for Students' Notes. 
 
 LONDON: 
 
 CHARLES GRIFFIN AND COMPANY. 
 
 EXETER STREET, STRAND. 
 
 1890. 
 
 [All Rights Reserved.] 
 
AUTHOR'S PREFACE. 
 
 THIS Pocket-Book is intended to serve for the reception of my 
 pupils' Sketches and Notes during Lectures and Practical Work, 
 and at the same time to facilitate a review of Classification. 
 
 SELENKA. 
 
 TRANSLATOR'S PREFACE. 
 
 IT is believed that this set of Schedules will be found generally 
 useful to students of Zoology, presenting as it does the leading- 
 features of the larger groups in a comparatively small space, while 
 clearness is gained by the use of various kinds of type. The blank 
 paper may profitably be employed to receive brief synopses from 
 voluminous lecture-notes, or, in some cases, definitions of families 
 and smaller subdivisions. 
 
 The Translation has been prepared from the Third German 
 Edition, but numerous additions and revisions have been made by 
 the Translator, who is also responsible for the Notes on Distribu- 
 tion (mainly prepared from Wallace) and the Geological Table. 
 
 J. R. A. D. 
 
 ABKRYSTWYTH, September 1890. 
 
,43 
 
 TABLE OF CONTENTS. 
 
 PAGE 
 
 GRADE A. PROTOZOA (Plastidozoa), . . . . .2 
 
 Class I. Rhizopoda (Gymnomyxa), ..... 4 
 
 Order 1. Proteomyxa, ....... 4 
 
 Order 2. Labyrinthulidea, ...... 4 
 
 Order 3. Mycetozoa (Myxomycetes), . . .. . .4 
 
 Order 4. Amoeboidea, ....... 5 
 
 Order 5. Foraminifera (Reticularia), . . . . .5 
 
 Order 6. Heliozoa, . . . . . .6 
 
 Order 7. Radiolaria, . . . . . .6 
 
 Class II. Infusoria (Plegepoda), ...... 7 
 
 Order 1. Flagellata (Mastigophora), ..... 7 
 
 Order 2. Ciliata, ..... .8 
 
 Order 3. Suctoria (Acinetaria, Tentaculifera), . .8 
 
 Class III. Gregarinida (Sporozoa), . . . . . .10 
 
 GRADE B. METAZOA (Enterozoa), . . . . .11 
 
 Phylogenetic Scheme, . . . , . . .11 
 
 Comparative Table of Metazoa, . . . . . 12, 13 
 
 SUBGRADE A. CCELENTERATA (Diploblastica), . . . . .14 
 
 Phylum I. Spongiae (Porifera), ...... 20 
 
 Order 1. Silicospongise, ....... 20 
 
 Order 2. Calcispongise, ....... 20 
 
 Phylum II. Cnidaria (Nematophora), . . . . .22 
 
 Class I. Hydrozoa (Polypomedusse), . . . . .22 
 
 Order 1. Hydromedusaa, . . . . . .22 
 
 Order 2. Siphonophora, . . . . . .22 
 
 Order 3. Acalephse (Scyphomedusse, Acraspeda), . . .22 
 
IV CONTENTS. 
 
 PAGE 
 
 Class II. Anthozoa (Actinozoa), . . . . . .29 
 
 Order 1. Rugosa (Tetracoralla), . . .29 
 
 Order 2. Alcyonaria (Octactinia, Octocoralla), . . .29 
 
 Order 3. Zoantharia (Hexactinia, Hexacoralla), . . .29 
 
 Class III. Ctenophora, ....... 32 
 
 SUBGRADE B. C(ELOMATA (Triploblastica), . . 33 
 
 Phylum I. Vermes, ........ 39 
 
 Class I. Platyhelmia (Platyhelminthes), . . . . .44 
 
 Order 1. Turbellaria, ....... 44 
 
 Order 2. Nemertina (Nemertea), . . . . .46 
 
 Order3. Trematoda, ....... 47 
 
 Order 4. Cestoda, ....... 50 
 
 Order 5. Mesozoa, ....... 53 
 
 Class II. Nemathelmia (Neniathelminthes), . . . .54 
 
 Order 1. Nematoda, . . . . . . .54 
 
 Order 2. Acanthocephala, . . . . . .58 
 
 Order 3. Chaetognatha, ....... 59 
 
 Table of Parasitic Worms, ..... 60, 61 
 
 Class III. Rotatoria (Rotifera), . . . . . .62 
 
 Class IV. Annelida (Annulata), . . . . . .63 
 
 Order 1. Archiannelida, ...... 63 
 
 Order 2. Chaetopoda, ..... .63 
 
 Order 3. Hirudinea (Discophora), . . . . .63 
 
 Class V. Gephyrea, .... .70 
 
 Phylum II. Echinodermata, ....... 73 
 
 Class I. Crinoidea, ........ 74 
 
 Class II. Asteroidea, .... 75 
 
 Order 1. Stellerida, ' [ 75 
 
 Order 2. Ophiurida, .... 75 
 
 Class III. Echinoidea, .... 77 
 
 Order 1. Regularia, .... 
 Order 2. Clypeastroidea, 
 Order 3. Spatangoidea, .... 
 
CONTEXTS. V 
 
 PAGE 
 
 Class IV. Holothuroidea, ....... 79 
 
 Order 1. Pedata, . .79 
 
 Order 2. Elasipoda, ....... 79 
 
 Order 3. Apoda, . . . . . . . .79 
 
 Phylum III. Arthropoda, . . . . . .81 
 
 Class I. Crustacea, . . . . . .85 
 
 Group A. Entomostraca, . . . . . .85 
 
 Order 1. Phyllopoda, ..... . .85 
 
 Order 2. Ostracoda, . . . . . - . .85 
 
 Order 3. Copepoda, . . . . . . .85 
 
 Order 4. Cirripedia, . . . . . . .85 
 
 Group B. Leptostraca, . . . . . .87 
 
 Group C. Malacostraca, . . . ' . . . .88 
 
 Order 1. Arthrostraca (Edriophthalmata), . . . .88 
 
 Order 2. Thoracostraca, . . . . . .88 
 
 Class II. Arachnida, . . . ," . . .90 
 
 Group A. Arachnida Branchiata, . . . . . .90 
 
 Order 1. Xiphosura, . . . . . . .90 
 
 Order 2. Eurypterina, . . . . . . .90 
 
 Order3. Trilobita, . . : . . . . .90 
 
 Group B. Arachnida Tracheata, . . . . . .92 
 
 Order 1. Acarina, ....... 92 
 
 Order 2. Pycnogonida (Pantopoda), . . . . .92 
 
 Order 3. Tardigrada, ....... 92 
 
 Order 4. Liuguatulidse, . . . . . .92 
 
 Order 5. Araneida, . . * . . . . .92 
 
 Order 6. Phalangidae, ....... 92 
 
 Order 7. Pedipalpi, . . . . . . .92 
 
 Order 8. Scorpionidee, ....... 92 
 
 Order 9. Pseudoscorpionida 1 , . . . . . .92 
 
 Order 10. Solifugse, ....... 92 
 
 Class III. Protracheata, ....... 94 
 
 Class IV. Myriapoda, ....... 96 
 
 Order 1. Chilopoda, ....... 96 
 
 Order 2. Chilognatha, . ... 96 
 
 Class V. Insecta (Hexapoda), . . . . . .99 
 
 Order 1. Orthoptera, ....... 99 
 
 Order 2. Thysanura (Aptera), . . 99 
 
VI CONTENTS. 
 
 . PAGE 
 Order 3. Pseudoneuroptera, . . . . . .99 
 
 Order 4. Hemiptera, ....... 99 
 
 Order 5. Neuroptera, ....... 99 
 
 Order 6. Trichoptera, ..... .99 
 
 Order 7. Strepsiptera, . . . . . . .99 
 
 Order 8. Diptera, . . . . . . .101 
 
 Order 9. Aphaniptera, ... . 101 
 
 Order 10. Coleoptera, ....... 101 
 
 Order 11. Hymenoptera, ...... 101 
 
 Order 12. Lepidoptera, . . . . . . .101 
 
 Phylum IV. Molluscoidea, . . . . . . .105 
 
 Class I. Polyzoa (Bryozoa), . . . . . . .105 
 
 Order 1. Vermiformia, . . . . . . .105 
 
 Order 2. Eupolyzoa, . . . . . . .105 
 
 Class II. Brachiopoda, . . . . . . .109 
 
 Order 1. Ecardines, . . . . . . .109 
 
 Order 2. Testicardines, . . . . . . .109 
 
 Phylum V. Mollusca, . . . . . . .113 
 
 Subphylum A. Lipocephala (Acephala), . . . . .113 
 
 Class I. Larnellibranchiata (Conchifera), . . . , .113 
 
 Order 1. Asiphonida, ....... 113 
 
 Order 2. Siphonida, ....... 113 
 
 Subphylum B. Glossophora, . . . . ... 118 
 
 Class I. Scaphopoda, ..... .118 
 
 Class II. Gastropoda, . . . . . . .121 
 
 A. Gastropoda Isopleura, . . . . . .121 
 
 Order 1. Solenogastres (Amphiueura), .... 121 
 
 Order 2. Polyplacophora, . . . . . .121 
 
 B. Gastropoda Anisopleura, ...... 121 
 
 Order 1. Streptoneura (Prosobrauchia), . . . .121 
 
 Order 2. Euthyneura, . . . . . .121 
 
 Class III. Pteropoda, . . . . . . . 126 
 
 Order 1. Thecosomata, . . ... 126 
 
 Order 2. Gymnosomata, ...... 126 
 
 Class IV. Cephalopoda (Siphonopoda). . . . . .129 
 
 Order 1. Tetrabranchiata, . . . . . .129 
 
 Order 2. Dibranchiata, . 129 
 
CONTENTS. Vll 
 
 PAGE 
 
 Phylum VI. Chordata, . . . . . . .335 
 
 Subphylum A. Hemichorda, ...... 135 
 
 Subphylum B. Urochorda (Tunicata), . . . . .138 
 
 Order 1. Larvacea (Perennichordata), ..... 138 
 
 Order 2. Ascidiaj, . . . . . . .138 
 
 Order 3. Thaliacea, .... . . .138 
 
 Subphylum C. Cephalochorda (Acrania), ..... 143 
 
 Subphylum D. Vertebrata (Craniata), . . . . .146 
 
 Table of Vertebrate Groups. . . . . . .147 
 
 Class I. Cyclostomi (Marsipobranchii), ..... 148 
 
 Order 1. Hyperotreti, . . . . . . .148 
 
 Order 2. Hyperoartia, . .148 
 
 Class II. Pisces, . . . . . . . .153 
 
 Order 1. Selachii (Elasmobranchii), ..... 153 
 
 Order 2. Holocephali, . . . . . . .153 
 
 Order 3. Ganoidei, . . . . . . .153 
 
 Order 4. Teleostei, . . . ... . .157 
 
 Order5. Dipnoi, . . . . . . .161 
 
 Class III. Amphibia, ....... 164 
 
 Order 1. Urodela (Caudata), . .164 
 
 Order 2. Batrachia (Anura), . . . . . .164 
 
 Order 3. Apoda (Gymiiophioua), . . . 164 
 
 Order 4. Stegocephali, . . 164 
 
 Class IV. Reptilia, ... ... 168 
 
 Lepidosauria (Plagiotremata), ...... 168 
 
 Order 1. Lacertilia (Sauria), . . . . . .168 
 
 Order 2. Pterosauria, . . . . . .168 
 
 Order3. Ophidia, . . 168 
 
 Hydrosauria, . .174 
 
 Order 4. Enaliosauria, . . . . .174 
 
 OrderS. Crocodilia, . . . . . . .174 
 
 Order 6. Chelonia, ... ... 174 
 
 Order 7. Dinosauria, . . . . . .174 
 
 Class V. Aves, . . . 180 
 
 Order 1. Saururse, . . .... 180 
 
 Order 2. Ratitae ... . .180 
 
 Order3. Cariuatae, . . . . . . .183 
 
Vlll CONTENTS. 
 
 1'AGE 
 
 Class VI. Mammalia, ..... .188 
 
 Subclass I. Prototheria (Ornithodelphia), . . . . .188 
 
 Order 1. .Monotremata, . . . 188 
 
 Subclass II. Metatheria (Didelphia), . . . . .191 
 
 Order 1. Marsupialia, ....... 191 
 
 Subclass III. Eutheria (Monodelphia), ... .195 
 
 Group A. Non-Deciduata, . ... 196 
 
 Order 1. Edentata (Bruta), .... .196 
 
 Order 2. Ungulata, . . . . . . .199 
 
 Order 3. Cetacea, . . . . . . .203 
 
 Order 4. Sirenia, . . . . . . .203 
 
 Group B. Deciduata, ... ... 207 
 
 Order 5. Kodentia (Glires), . . . 207 
 
 Order 6. Proboscidea, . . .212 
 
 Order 7. Hyracoidea (Lanmugia), ..... 212 
 
 Order 8. Insectivora, ....... 215 
 
 Order 9. Cheiroptera. ... ... 215 
 
 Order 10. Carnivora (Ferae), . . . . . .218 
 
 Order 11. Prosimise (Lemuroidea), . . . . .222 
 
 Order 12. Primates, . . . . . . .222 
 
 Principles of Distribution, ....... 227 
 
 Distribution of Mammals, . . . . . . .231 
 
 Table showing the Geological Eange of the Chief Animal Groups. . . 238 
 
PROTOZOA. 
 
 Grade A. PROTOZOA (Plastldozoa). 
 
 Unicellular organisms. The cell-body (sarcode, protoplasm) effects the 
 reception and assimilation of food ; the endoplast or nucleus (chromatin 
 and nucleolus ; nuclear fluid) plays an important part in reproduc- 
 tion. One or more contractile vacuoles frequently present. Keproduction 
 effected by fission, gemmation, or spore-formation (often after preceding 
 conjugation or copulation). 
 
 All Protozoans live in water, damp places, or as parasites in the juices 
 of other animals. 
 
4 EHIZOPODA. 
 
 Class I. Rhizopoda (Gymnomyxa). 
 
 Protozoans devoid of cuticle whose protoplasmic body takes in food, 
 and, in many cases, moves by means of retractile pseudopodia. A skeleton 
 frequently present. Reproduction by fission or formation of swarm- 
 spores. 
 
 Order 1. Proteomyxa. A heterogeneous group of small forms with 
 inconspicuous nuclei, and pseudopodia of various nature : Protomyxa, 
 Protomonas, Vampyrella, Protogenes, Archerina. 
 
 Order 2. Labyrinthulidea. Protozoans consisting of a protoplasmic 
 network with travelling spindles : Labyrinthula, Chlamydomyxa. 
 
 Order 3. Mycetozoa (Myxomycetes). Rhizopods in which the body is 
 an active plasmodium, producing coated spores : Ceratium, Trichia, 
 ^Sthalium (flowers of tan). 
 
RHIZOPODA. 5 
 
 Order 4. Amceboidea. Shape-changing Rhizopods with a contractile 
 vacuole. Movement and reception of food effected by means of blunt 
 pseudopodia. Sometimes a skeleton. Reproduction usually by binary 
 fission, sometimes by gemmation. Resting-cysts (hypnocysts) common 
 Amoeba, Lithamoeba, Hyalodiscus, Plakopus, Pelomyxa, Difflugia 
 with membranous shell strengthened by foreign particles, Arcella with 
 shagreen-like shell. 
 
 Order 5. Foraminifera (Reticularia). Rhizopods with an amoeba -like 
 body, emitting filiform pseudopodia which branch and anastomose. Pos- 
 sess a (usually calcareous) shell. 
 
 A. Imperforata. Shell with a single or a sieve-like opening ; 
 (more rarely two or a few openings). Gromia, one-chambered. Milio- 
 lina, many-chambered. 
 
 B. Perforata. Shell with pores. Lagena. Orbulina ; Globi- 
 gerina. Polystomella; Nummulina. Eozobn, a doubtful form from 
 the Precambrian (Laurentian). 
 
6 RHIZOPODA. 
 
 Order 6. Heliozoa. Globular Rhizopods, with fine stiff radiating 
 pseudopodia. Protoplasm containing one or more nuclei and contractile 
 vacuoles, and very numerous non-contractile vacuoles. A siliceous 
 skeleton sometimes present. Cyst- and spore-formation may take place. 
 Actinosphserium and Actiiiophrys sol, sun animalcule, without 
 skeleton. Raphidiophrys, with loose tangential spicules. Acantho- 
 cystis, with radial spicules. Clathrulina, stalked, and with perforated 
 spherical shell. Lead on to 
 
 Order 7. Radiolaria. Marine Rhizopods of globular or conical shape, 
 with differentiated protoplasmic body. Radiating filamentous pseudo- 
 podia, central nucleus-containing capsule, and (generally) a radial or 
 tangential skeleton of silica or acanthin. No contractile vacuole. Re- 
 production by fission or swarm-spores. Parasitic (?) or symbiotic (?) 
 yellow corpuscles very generally present. Actinomma. Thalassicolla, 
 no skeleton. Collozoum, colonial and without skeleton. Acantho- 
 metra. Eucyrtidium, 
 
INFUSORIA. 7 
 
 Class II. Infusoria (Plegepoda). 
 
 Protozoans with a definitely-shaped body invested by a cuticle 
 Locomotion effected, and food- and oxygen-bearing currents produced by 
 vibratile membranes, flagella, or cilia. 
 
 Order 1. Flagellata (Mastigophora). With one or more flagella, and a 
 contractile vacuole. Reception of food effected by short broad pseudo- 
 podia, or through a cell-mouth. Some possess chlorophyll, and then 
 live partly or entirely (holophytic) like green plants. Reproduction by 
 longitudinal fission or by spores. Conjugation frequent. Monas, Cerco- 
 monas, Uroglena. Bodo. Euglena. Pandorina, Volvox, Haemato- 
 COCCUS, holophytic, and first two colonial. Codosiga, with single 
 flagellum surrounded by oral collar. Ceratium, Peridinium, and 
 Noctiluca, marine forms, with shell and two flagella. 
 
 The lower Flagellates are allied by spore-formation and presence of 
 flagella to the Schizomycetes (Bacterium ; Leptothrix; Cladothrix), the 
 higher to the Ciliata. 
 
8 INFUSORIA. 
 
 Order 2. Ciliata ( = Infusoria in limited sense). Protozoans of stable 
 form, with firm ectosarc (cortical layer), giving origin to variously dis- 
 posed cilia which pierce the cuticle when present. Usually possess 
 nucleus, paranucleus ; contractile vacuole ; mouth, gullet, and anal spot ; 
 contractile fibres ; and sometimes bristles and stalks. Reproduction 
 effected by fission, gemmation, and spore-formation. Permanent or 
 temporary conjugation. Encystment. 
 
 Holotricha: body uniformly covered with short cilia, no adoral 
 ciliated zone. Paramoecium aurelia, slipper animalcule ; Opalina 
 ranarum, without mouth and anus, parasitic in rectum of frog. 
 
 Heterotricha : the entire body covered with cilia arranged in 
 longitudinal rows, an adoral band of cilia present. Stentor poly- 
 morphus (cceruleus) ; Balantidium and Nyctotherus in rectum of 
 frog. 
 
 Hypotricha: mouth and anus placed on the ventral surface which 
 is provided with locomotor cilia and bristles, dorsal surface naked or 
 with fine tactile cilia. Stylonichia mytilus, Oxytricha gibba. 
 
 Peritricha : cylindrical ; with an adoral spiral of cilia and fre- 
 quently with a girdle of cilia. Longitudinal fission. Vorticella 
 nebulifera, V. microstoma, Carchesium, Epistylis, bell animalcules, 
 all stalked. 
 
 Order 3. Suctoria (Acinetaria, Tentaculifera). Usually fixed In- 
 fusorians, devoid of cilia in the adult condition, but possessing bundles 
 of suctorial tentacles. Reproduction chiefly by internal gemmation, with 
 production of free-swimming ciliated young. Acineta, Podophrya 
 gemmipara. 
 
10 
 
 INFUSORIA. 
 
 Class III. Gregarinida (Sporozoa). 
 
 ess unicellular endoparasites, v 
 
 bion by spores (pseudonavicell 
 ,,_ it. Gregarina blattarum. I 
 seminales of Earthworm. Psorosperms. 
 
 -L / 
 
 Mouthless unicellular endoparasites, with cortical layer and cuticle. 
 -Reproduction by spores (pseudonavicellse) following conjugation and 
 encystment. ^Gregarina blattarum. Monocystis agilis in vesicul* 
 
 ^'1 r*f ln*7-/~irTVl T5o /NWArtwyN^n^k^i 
 
METAZOA. 
 
 11 
 
 Grade B. METAZOA (Enterozoa). 
 
 The unicellular Protozoa are contrasted with the remaining animals 
 forming Grade B METAZOA, which possess cellular differentiated 
 tissues and organs. Sexual reproduction by ova and spermatozoa. From 
 the fertilized ovum a Blastula is produced by continued cell-division 
 (cleavage), and from this a Gastrula with Ectoderm and Endoderm. 
 
 The probable phylogenetic connection of the Metazoan classes is shown 
 in the following scheme ; and several important typical differences are 
 collected together in the annexed table : 
 
 Mammalia ^ 
 
 Aves g 
 
 Reptilia $ 
 
 Amphibia 
 Pisces Cyclostomi 
 
 Cephalochorda 
 
 Cephalopoda Pteropoda 
 
 Hemichorda 
 
 Gastropoda 
 to | 
 
 ?> Lamellibranchiata 
 
 Molluscoidea \ 
 
 Insecta 
 Myriapoda 
 Urochorda Protracheata 
 
 Nemertea 
 
 Cestoda Mesozoa 
 
 V 
 
 Trematoda- 
 
 Arachnida 
 
 Crustacea 
 
 / 
 Annelida 
 
 Holothuroidea 
 Echinoidea 
 Asteroidea 
 Criuoidea 
 
 Acanthoc 
 
 Nematoda 
 
 irbellaria 
 Ctenophora 
 Spongise Cnidaria 
 
 Ccelenterata 
 
 Cell Colonies 
 
 Protozoa 
 
12 
 
 ( ) = in a few or the 
 minority of cases. 
 
 r= radial. w 
 b= bilateral. &. 
 
 V- 
 
 s= segmented. 
 
 Gut. 
 
 5 
 
 ! i 
 
 " ii 
 
 & 08 
 
 Nervous 
 System. 
 
 ill . 
 1 *1 1 
 
 S> *C 2 
 
 II II I' 
 tf 8 
 
 H = hermaphrodite. 
 s = separate sexes. 
 
 P= parasites. 
 f=free-living. 
 
 Spongise, 
 
 (r) 
 
 inhalent and ex- 
 halent aper- 
 tures ; canal 
 system 
 
 scattered 
 cells 
 
 H s 
 
 f 
 
 Cnidaria, 
 
 r (b) 
 
 m; gastro-vas- 
 cular sac 
 
 network, often 
 plus ring or 
 
 00 G 
 
 (H) s 
 
 f 
 
 Turbellaria, 
 
 b 
 
 m; tube, often 
 branched 
 
 GG 
 
 H (8) 
 
 f 
 
 Nemertina, 
 
 b 
 
 m, a, tube 
 
 GG 
 
 (H) s 
 
 f 
 
 Trematoda, 
 
 b 
 
 m, forked tube 
 
 GG 
 (R) 
 
 H 
 
 P 
 
 Cestoda, 
 
 b, often 
 strobilized 
 
 nil 
 
 commissure in 
 head, lateral 
 cords 
 
 H 
 
 P 
 
 Nematoda, 
 
 b 
 
 m, a, tube 
 
 R 
 
 s 
 
 P f 
 
 Acanthocephala, 
 
 b 
 
 nil 
 
 G 
 
 8 
 
 P 
 
 Rotatoria, 
 
 b 
 
 ? m, a 
 <5 rudim. 
 
 G 
 
 S 
 
 
 Annelida, 
 
 b s 
 
 m, a 
 
 GG; ventral 
 chain 
 
 (H) s 
 
 (P) f 
 
 Echinodermata, 
 
 r 
 larvae b 
 
 m, a 
 or m only 
 
 R, radial 
 nerves 
 
 (H) s 
 
 f 
 
 Arthropoda, 
 
 b s 
 
 m, a 
 
 GG ; ventral 
 chain 
 
 (H) s 
 
 (P)f 
 
 Polyzoa, 
 
 b 
 
 m, a 
 
 G 
 
 H s 
 
 f 
 
 Brachiopoda, . 
 
 b s? 
 
 m, a 
 or m only 
 
 R, on which 
 are variable 
 number of G 
 
 (H) s 
 
 f 
 
 Mollusca, 
 
 b 
 
 m, a 
 
 R with three 
 pairs of G 
 
 (H) s 
 
 (P) f 
 
 Balanoglossus, 
 
 b 
 
 m, a 
 
 dorsal, partly 
 hollow cord 
 connected 
 with ventral 
 cord 
 
 s 
 
 f 
 
 Urochorda, 
 
 b s 
 
 m, a 
 
 dorsal neural 
 tube in Appen- 
 dicularia and 
 embryos, G. 
 in most adults 
 
 H (s) 
 
 f 
 
 Cephalochorda, 
 
 b s 
 
 m, a 
 
 dorsal neural 
 tube 
 
 s 
 
 f 
 
 Vertebrata, . 
 
 b s 
 
 m, a 
 
 dorsal neural 
 tube 
 
 (H) s 
 
 (P)f 
 
13 
 
 Reproduction may 
 exhibit 
 
 Blood Vascular 
 
 
 
 
 
 
 
 
 System. 
 
 
 
 
 
 
 s 1 
 
 ill 
 
 nation of 
 aeration. 
 
 "O 
 
 Special Respira- 
 tory Organs 
 present 
 
 d 
 
 ] 
 
 1 
 
 
 I 
 
 ti 
 
 |> 
 
 1 i 
 
 
 i 
 
 1 $ 
 
 
 
 
 5 
 
 "8 
 
 o -3 
 
 
 
 & 1 
 
 
 I 
 
 .a P, a 
 
 i 
 
 II II 
 
 O 
 
 
 a 
 
 11 it 
 
 
 f 
 
 b 
 
 
 
 
 almost all Da 
 
 
 U) 
 
 b m t 
 
 i 
 
 
 
 almost all m 
 
 
 (m) 
 
 (o) c 
 
 Ciliated pits in 
 head 
 
 almost all m 
 
 
 b m a 
 
 
 
 
 
 f b m a 
 
 
 
 
 
 
 
 \ (m) f 
 
 
 
 | 
 
 
 
 P 
 
 
 trochal 
 apparatus ? 
 
 mostly f 
 
 
 (O 
 
 m 
 
 o in Hirudinea 
 c in Chsetopoda 
 and Gephy- 
 rea 
 
 often gills 
 
 mostly m 
 (O (1) 
 
 
 (O 
 
 (ra) 
 
 c 
 
 water-vascular 
 system 
 
 m 
 
 
 (P) 
 
 (m) 
 
 
 
 gills, lung- 
 books, 
 tracheae 
 
 m f 1 
 
 
 b 
 
 m 
 
 c in Phoronis, 
 absent else- 
 where 
 
 lophophore 
 
 m (f) 
 
 
 m 
 
 o presence 
 disputed 
 
 lophophore 
 
 m 
 
 
 (m) 
 
 gills, lungs 
 
 m f 
 
 m 
 
 c 
 
 perforated 
 pharynx 
 
 m 
 
 
 b m (a) 
 
 
 
 perforated 
 pharynx 
 
 m 
 
 
 
 c 
 
 perforated 
 pharynx 
 
 m 
 
 
 (m) 
 
 c 
 
 ditto, with gill- 
 filaments ; 
 lungs, 
 allantois. 
 
 m f 1 
 
 
14 C03LENTERATA. 
 
 Subgrade A. CCELENTERATA (Diploblastica). 
 
 Metazoans of prevailing radial symmetry, with wide digestive cavity 
 (gastrovascular system). No body-cavity (as blood or lymph-reservoir). 
 Ectoderm and endoderm separated by a supporting lamella (mesoglcea). 
 Asexual reproduction often obtains (gemmation, fission, frequently lead- 
 ing to formation of stocks). The development usually exhibits a meta- 
 morphosis (with planula larva), and often an alternation of generations 
 (sexual and asexual generations alternating). With few exceptions 
 (Spongilla, Hydra, &c.), marine. 
 
20 SPONGLE. 
 
 Phylum I. SPONGI^ (Porifera). Sponges. 
 
 The digestive tract has the form of a much-branched canal-system. 
 Many of the endoderm cells (collar-cells), which may be limited to 
 flagellated chambers, are provided with a flagellmn and collar. Numerous 
 microscopic pores (inhalent or nutritive apertures), and one or more 
 oscula (exhalent apertures). The mesogloea contains sense-cells, con- 
 tractile fibrous cells, supporting cells, skeletogenous cells (together with 
 horny fibres, and calcareous or siliceous spicules), pigment cells, wander- 
 ing cells, ova, and spermatozoa. Asexual reproduction by budding, 
 through gemmules, &c. Sexes mostly separated ; usually viviparous. 
 Thread-cells absent, in contrast to the Cnidaria. Marine, with few 
 exceptions. 
 
 Order 1. Silicospongice (Fibrospongiae, Micromastictora). Usually 
 possess a skeleton of horny fibres, siliceous spicules, or both. Collar-cells 
 small. 
 
 Tetractinellida3 (Lithospongias), siliceous sponges with 4-rayed 
 spicules. Geodia, Monactinellidse. 
 
 Hexactinellida3 (Hyalospongise), 6-rayed siliceous spicules. 
 Euplectella, Venus' flower-basket ; Hyalonema, glass-rope sponge. 
 
 H a 1 i c h o n d r i B, skeleton of horny fibres and siliceous spicules. 
 Reniera, Spongilla fluviatilis, fresh-water sponge. 
 
 Ceratosporigia?, horny sponges. Euspongia officinalis adriatica, 
 bath sponge. 
 
 Myxospongise, gelatinous sponges, without skeleton. Halisarca 
 lobularis. 
 
 Order 2. Caldspongice, calcareous sponges. Grantia, Leuconia, 
 Sycon. 
 
22 CNIDARIA. 
 
 Phylum II. CNIDAEIA (JSTematophora). 
 
 Eadial animals without pore-canals, and with thread-cells (or adhesive 
 cells) in their epithelium. Nerves and sense-organs. 
 
 Class I. Hydrozoa (Polypomedusse). 
 
 Polypes and medusae with digestive cavity sac-like, or narrowed 
 (gastro-vascular space). No gullet (stomodaeum). Development chiefly 
 by alternation of generations (medusoid sexual generation, or free- 
 swimming medusa3 as sexual animals). 
 
 Order 1. Hydromedusce. Hydroid stocks devoid of mesenteric folds, 
 and with sexual medusoid buds or small craspedote medusae as sexual 
 animals. The nursing hydroid stock often possesses a horny cuticular 
 skeleton (perisarc) ; the sexual hydromedusse mostly small, with only 
 4, 6, or 8 radial vessels, muscular velum, naked marginal sense organs, 
 eye-spots (Ocellatae), or otocysts (Vesiculatae), double marginal nerve- 
 ring, and sexes usually separate. The blastula formed by delamination. 
 
 Gymnoblastea-Anthomedusae, perisarc stops short at bases 
 of polypes ; medusas with ocelli, and with genital organs in the manu- 
 brium. Hydra viridis, H. fusca, solitary freshwater hermaphrodites, 
 devoid of perisarc or medusoid buds. Cordylophora lacustris, the 
 sexual buds remain attached. Eudendrium. Syncoryne sarsii, with 
 Sarsia tubulosa as medusa. Hydractinia and Tubularia, medusae 
 attached. Ccenograptus, Ordovician. Ctenaria ctenophora, a tran- 
 sitional form to the Ctenophora. 
 
 Calyptoblastea-Leptomedusae, perisarc forms hydrothecae 
 and gonangia ; medusae with ocelli or otocysts, and genital organs in the 
 course of the radial canals. Sertularia and Plumularia with attached, 
 Campanularia and Obelia with free medusae. .!quorea, large medusa 
 with numerous radial vessels and marginal tentacles. 
 
 Trachymedusae, craspedote medusae without gastral filaments, 
 and with a velum. Dense gelatinous umbrella. Sense-organs as ten- 
 taculocysts. The asexual hydroid generation has fallen out. ^Egina 
 and Geryonia with 6, Liriope with 4 radial canals. The freshwater 
 medusa, Limnocodium (? with a hydroid stage), possibly belongs here. 
 
 Hydrocorallinae, polymorphic colonies with calcified cuticular 
 skeleton ; medusoid stage represented by sporosacs. Millepora. 
 Stylaster. 
 
 Order 2. Siphonophora, free-swimming polymorphic stocks. Phy- 
 sophora hydrostatica. Physalia pelagica, Portuguese man-of-war. 
 Diphyes. Velella. 
 
 Order 3. Acalephce (Scyphomedusse, Acraspeda). Medusae with gastral 
 
CNIDARIA. 23 
 
 filaments, lappets to umbrella, covered marginal sense-organs (tentaculo- 
 cysts), and central nervous system in the form of groups of ganglion-cells. 
 No velum. Development seldom direct (Pelagia, Charybdeidae ?), usually 
 with alternation of generations, the asexual generation being a short 
 broad scyphistoma, which strobilizes to produce medusae. The blastula 
 formed by invagination. 
 
 Calycozoa (Lucernariee), fixed scyphistoma form without medusoid 
 stage. Lucernaria. 
 
 Marsupialida, a high arched umbrella with 4-divided margin ; 
 four interradial tentacles, a pseud-velum, and four gastric pouches 
 wiih four lamellar genital glands on the partitions separating them. 
 Charybdaea. 
 
 Discomedusae (Discophora), discoid acraspedote medusae with 
 8-divided umbrella-edge, slightly curved umbrella, genital glands in 
 floor of stomach, and at least eight tentaculocysts situated in notches. 
 Oral tentacles usually large. Pelagia noctiluca. Amelia aurita, 
 small, with branched radial vessels united by a ring-canal. Rhizostoma 
 Cuvieri, without marginal filaments, but with dorsal and ventral oral 
 frills ; the central mouth-opening of the Ephyra (young form) converted 
 later by coalescing folds into numerous suctorial pores. 
 
ANTHOZOA. 29 
 
 Class II. Anthozoa (Actinozoa). Corals. 
 
 Polypes with gullet (stomodseum), which, is fixed to the body- wall by 
 mesenteries, which bear mesenteric filaments and the endodermal genital 
 glands. Sexes generally separated. A crown of hollow tentacles sur- 
 rounds the elongated mouth. Usually with a firm calcareous non- 
 superficial skeleton, and frequently colonial by budding. For the most 
 part inhabitants of shallow water (coral reefs). 
 
 Order 1. Rugosa (Tetracoralla). Palaeozoic (except Holocystis) corals, 
 with numerous tetramerously grouped septa. Cyathophyllum. 
 
 Order 2. Alcyonaria (Octactinia, Octocoralla), with eight pinnate 
 tentacles, and as many uncalcified mesenteric folds with ventral retractor 
 muscles. Calcareous spicules usually present in the mesoglcea. 
 Alcyonium digitatum, dead man's fingers, stocks of fleshy polypes. 
 Pennatula rubra and Veretillum, sea-pens, stocks, of which the naked 
 basis sticks in the mud, horny axial skeleton ; the latter dioecious. 
 Gorgonia ; Corallium rubrum, red coral. Tubipora purpurea, organ- 
 pipe coral. Heliopora, massive skeleton, dimorphic polypes. ,: 
 
 Order 3. Zoantharia (Hexactinia, Hexacoralla). The number of the 
 non-pinnate tentacles, and mesenteric pouches, six, or a multiple thereof. 
 Mesenteries usually paired, and the retractor muscles not arranged as 
 in Alcyonaria. Generally a compact skeleton. Actinia mesembry- 
 anthemum, sea anemone, a solitary form with several alternating circlets 
 of tentacles ; fixed by an adhesive disc ; Cerianthus, elongated with an 
 aboral pore ; hermaphrodite. Antipathes, with six tentacles and a 
 horny skeletal axis. 
 
 We group together as Madreporaria the forms with a firm cal- 
 careous skeleton. Aporosa : Caryophyllaea. Oculina virginea. 
 Astrsea. Maeandrina, brain coral. Fungia discus, mushroom coral. 
 Perforata : Madrepora cervicornis. Asteroides. 
 
32 CTENOPHORA. 
 
 Class III. Ctenophora. 
 
 Free-swimming hermaphrodites with eight rows of external ciliary 
 plates, with gullet (stomodseum) and gastro-vascular canals arranged 
 bilaterally. Usually with two retractile tentacles. Thread-cells replaced 
 by adhesive cells. Cydippe. Cestus Veneris. Beroe Forskalii. 
 Cceloplana, a creeping form. 
 
C(ELOMATA. 33 
 
 Subgrade B. CCELOMATA. (Triploblastica). 
 
 Bilaterally symmetrical forms with a praeoral region (head). A third 
 cellular body-layer, the mesoderm, present between the embryonic ecto- 
 derm and mesoderm. Within this a body-cavity (coelom) is usually 
 developed outside the digestive cavity. 
 
VERMES. 39 
 
 Phylum I. VERMES. Worms. 
 
 Bilateral forms with unsegmented or segmented body, paired excretory 
 organs, dermal musculature, &c. A sharp diagnosis of this group is the less 
 easy, since it not only contains the most different forms, but also con- 
 necting links with all the higher phyla. The lower worms (Turbellaria) 
 similarly c.onnect themselves with the Ccelenterata (Ctenophora). 
 
 The group of Vermes has long been made a receptacle for all sorts of doubt- 
 ful forms, and, since the removal of the Tunicata from the Molluscoidea, the 
 Polyzoa and Brachiopoda have usually been added to it. Ray Lankester 
 abandons both Vermes and Molluscoidea, and places their classes in separate 
 phyla. 
 
 (1.) Platyhelmia. (Leeches are included here as well as ordinary flat- 
 worms. ) 
 
 (2.) ISTematoidea (including Nematoda and Chsetognatha). 
 
 (3.) Acanthocephala. 
 
 (4.) Gastrotricha. 
 
 (5.) Podaxonia (Gephyrea + Polyzoa + Brachiopoda). 
 
 (6.) Appendiculata, seep. 62. TB. 
 
44 VERMES. 
 
 Class I. Platyhelmia (Platyhelminthes). 
 Flat-Worms. 
 
 Unsegmented worms, generally with flattened bodies. Body-cavity 
 imperfectly developed (mesoderm generally parenchymatous), and usually 
 an excretory system of longitudinal trunks with narrow branches. 
 Cerebral ganglia generally present, but never a ventral nerve-cord. 
 Mostly hermaphrodite. Many forms parasitic. 
 
 Order 1. Turbellaria. Free-living flat- worms, with soft, ciliated, tricho- 
 cyst-bearing skin. Mouth and muscular pharynx, but no anus. Live 
 in water or damp places. 
 
 Rhabdocoelida, small forms with intestine, when present, a simple 
 tube. Convoluta, no intestine. Micr stomum, fission, stiff tactile 
 hairs ; Vortex, Monotus. 
 
 Dendroccelida, large forms, with branched intestine and follicular 
 testes. (a) Triclades (Monogonopora), elongated Dendrocceles with three 
 main divisions to intestine, and single genital opening. Land (Geodes- 
 mus in pot-earth ; Bipalium) and freshwater (Planaria torva, P. dioica ; 
 Dendroccelum lacteum) Planarians. Gunda (internal organs segment- 
 ally arranged), marine. (6) Polyclades (Digonopora), flattened leaf-like 
 marine Dendrocoales, with a central stomach and two genital openings. 
 Leptoplana tremellaris ; Thysanozoon (metamorphosis with Miiller's 
 larva); both marine. 
 
46 VERMES. 
 
 Order 2. Nemertina (Nemertea). Elongated ciliated worms with a 
 dorsal eversible proboscis (surrounded by nervous commissures), a straight 
 gut terminating in an anus, blood-vessels and spaces (body-cavity), a 
 pair of cephalic pits and two anterior nephridia. Nearly all marine, 
 and with sexes separate. 
 
 A 11 o p 1 a, proboscis devoid of armature, three layers of muscle in body- 
 wall, and development sometimes with metamorphosis (larva of Desor, 
 and Pilidium). Linens longissimus. Borlasia. Pelagonemertes. 
 
 E n o p 1 a (Hoplonemertea), proboscis armed with stylets, two layers of 
 muscle in body-wall, development direct. Nemertes. Tetrastemma 
 obscura, viviparous. Malacobdella. 
 
VERMES. 47 
 
 Order 3. Trcmatoda. Flukes. Parasites with mouth-opening placed 
 in an anterior sucker, forked or branched aproctous intestine, and supra- 
 pharyngeal ganglia. Usually provided with organs of adhesion in addi- 
 tion to the anterior sucker. Nearly all hermaphrodite [typical parts, 
 two testes with vasa deferentia, cirrus-sac with cirrus. Ovary (ger- 
 marium), two yolk-glands (vitellaria), oviduct, ootype with copulatory 
 passage (Laurer's canal), shell-glands]. Mostly oviparous. 
 
 D i s t o m e sd endoparasites with not more than two suckers. Develop- 
 ment with metamorphosis and alternation of generations. [From the 
 egg an embryo, usually ciliated, is developed, generally in water, This 
 penetrates into an intermediate host (usually a mollusc), and develops 
 into a redia (with mouth and gut) or sporocyst (without gut), which in- 
 directly or directly produces cercariae (tailed, with forked intestine). 
 The cercaria, often after a second migration into another invertebrate host 
 (e.g., a water-snail), ultimately reaches the final host (a vertebrate) in 
 which the sexual form is attained]. Distqmum hepaticum (Fasciola 
 hepatica), liver-fluke. Body covered with chitinous prickles. In the bile- 
 ducts of the sheep and other domestic animals-, occasionally of man. 
 Ciliated aquatic embryo, with x-shaped eye spot ; the asexual nurse-forms 
 (sporocyst and redia) in Limnseus truncatulus. From the redia tailed 
 cercariae are developed, which become free and encyst on grass, &c., with 
 which they are swallowed by the vertebrate host. D. crassum, in the 
 intestine of the Chinese. D. haematobium (Bilharzia), bisexual ; in the 
 portal, mesenteric, and vesical veins of the Abyssinians. Monostomum 
 flavum, in water birds, the young form (Cercaria ephemera) in 
 Planorbis. 
 
 Poly sto mere, mostly ectoparasites with more than two suckers. 
 Development direct, or without considerable metamorphosis. Poly- 
 Sternum integerrimum, in the urinary bladder of the frog. Egg pro- 
 duction commences in the spring (mutual fertilization), and the larva, 
 which is hatched in the water, enters the gill-chamber of a tadpole, loses 
 its five ciliated bands, and passing down the alimentary canal reaches 
 the bladder in eight weeks. Here it becomes sexually mature in three 
 or more years. (It rarely reaches the sexual stage in the gill-cavity, in 
 which case it dies after producing an egg.) Diplozqon paradoxum, on 
 the gills of many freshwater fish ; two separate animals (Diporpa) par- 
 tially fuse to a compound individual ; eggs with attachment threads ; 
 larva ciliated. Gyrodactylus. 
 
50 VERMES. 
 
 Order 4. Cesioda. Tape-worms. Elongated endoparasites, without 
 gut or sense-organs, but with an attachment apparatus at the anterior 
 end. Excretory organs consist of longitudinal canals, with branched 
 canalettes. Hermaphrodite (numerous testes, with vas deferens, cirrus, 
 and cirrus-sac. Ovaries, yolk-glands, spermatheca, shell-glands, uterus, 
 and vagina). Numerous sets of reproductive organs usually present, 
 contained in generative " segments " (proglottides) budded off from an 
 anterior head. With advancing ripeness the male organs disappear ; then 
 the female organs with the exception of the exit passages. Two nerve- 
 trunks, united in the head. Development seldom direct or with 
 alternation of generations, mostly with a metamorphosis. The eggs 
 generally reach dung-heaps or water, then enter with the food the 
 stomach of omnivorous or plant-eating animals, where the egg-shells are 
 ruptured ; the freed six- (rarely four-) hooked embryos bore into the 
 blood-vessels, and develop in the liver, lungs, brain, or muscles to encysted 
 measles (bladder- worm, cysticercus, cysticercoid, ccenurus, echinococcus) ; 
 after passive removal into the intestine of a carnivorous, insectivorous, 
 or omnivorous animal, the everted bladder-worm (scolex) fixes itself 
 firmly to the intestinal wall and grows into a jointed form (strobila). 
 Caryophyllseus mutabilis, non-jointed, in the intestine of Cyprinoids ; 
 young form in Tubifex rivulorum. Archigetes Sieboldii, non-jointed, 
 with direct development, in body-cavity of Tubifex rivulorum. Both- 
 riocephalus with two adhesive pits, young form a scolex ; genital open- 
 ings in the middle of the ventral surface of the proglottis. B. latus, 
 24 to 30 feet long ; in Russia, Poland, Switzerland, and S. France. The 
 eggs, enclosed in shells, hatch in water, the ciliated embryo enters a first 
 intermediate host, and with this as a scolex into the intestine of the pike 
 or burbot. B. cordatus, 3 feet long, in the intestines of dog and man 
 in Greenland. Trisenophorus nodulosus in the intestine of the pike, 
 young form in liver of carp. Ligula simplicissima, non-jointed, in 
 the intestine of water-fowls, and the body-cavity of fishes. Tsenia 
 solium, two to three metres long, with four suckers and a double circlet 
 of (26) hooks; in the intestine of man. Young form (measles, Cysti- 
 cercus cellulosse) in the muscles and subcutaneous connective tissue of 
 swine, seldom of deer, dog, and cat, occasionally in muscles, eye, or brain 
 of man (self-infection). T. saginata (mediocanellata), in the intestine 
 of man, without circlet of hooks ; four metres long ; measles in muscles 
 of the ox. T. ccenurus, in intestine of sheep-dog ; young form in brain 
 of one year old sheep (seldom in the body-cavity of rabbit, &c.) as 
 Ccenurus cerebralis, the stagger-worm; (from the walls of the measles 
 numerous tape-worm heads bud out. Alternation of generations). T. 
 echinococcus, in the intestine of the dog, three to four millimetres long, 
 forming but few proglottides. The corresponding bladder-worm with 
 budding secondary and tertiary cysts in the liver and lungs of domestic 
 animals (Echinococcus veterinorum, E. scolicipariens), or of man (E. 
 hominis, E. altricipariens). 
 
VERMES. 53 
 
 Order 5. Mesozoa. Multicellular endoparasites of small size and 
 extremely simple structure. A ciliated ectoderm, and an endoderm of 
 one or several cells giving rise to the genital products. Sexes separate. 
 No mesoderm. Probably degenerate. Systematic position doubtful. 
 
 Dicyemidse (Rhombozoa). A single endoderm cell. The male 
 (infusoriform embryo) top-shaped. The females either monogenic or 
 diphygenic, i.e., producing females only, or females at first and then males. 
 Dicyema (in cuttle-fishes, Octopus, Sepia). 
 
 Orthonectidse. Endoderm of several cells, some originating 
 muscle-fibres, and others sexual products. The male elongated and 
 annulated. The female dimorphic (annulated cylindrical female, flat 
 female) and oviparous. Rhopalura Giardi, in the genital pouches of 
 the Ophiuroid Amphiura squamata. 
 
54 VERMES. 
 
 Class II. Nemathelmia (Nemathelminthes). 
 Round-Worms. 
 
 Body cylindrical, unsegmented, devoid of lateral locomotor append- 
 ages, with papillae or armature of hooks at the anterior end. No blood- 
 vessels nor specialized respiratory organs. Predominantly parasitic. 
 Sexes separate. Development generally without metamorphosis. 
 
 Order 1. Nematoda. Thread- worms. Usually possess a straight ali- 
 mentary canal, and paired excretory tubes contained in lateral lines and 
 opening by a ventral pore behind the terminal mouth. The male with 
 curved tail-end and copulatory spicules, smaller than the female. The 
 young form often inhabits an intermediate host. Ascaris lumbri- 
 coides, round-worm of man (and as a smaller variety in swine) ; the 
 transference probably takes place by an intermediate host (Julus guttu- 
 latus ?). A. mystax, in the cat and dog, occasionally in man . A. mega- 
 locephala, in the horse and ox. Oxyuris vermicularis, thread- worm, 
 in the large intestine of man ; the female ten millimetres long. Stron- 
 gylus. Rhabdonema nigrovenosa, as a viviparous hermaphrodite in 
 the frog's lung, producing a generation with separate sexes (Rhabditis), 
 which becomes sexually mature in damp earth (heteromorphous genera- 
 tion). Dochmius duodenalis, 16 millimetres long ; in the small intes- 
 tine of man, in Europe, Egypt, Comoro Islands, Brazil, and Cayenne. 
 Trichocephalus dispar, whip-worm, in the human colon ; transfer 
 without intermediate host by filthy food. Trichina spiralis, in the 
 intestine of man and other omnivorous mammals. The viviparous 
 female trichina of the intestine, about eight days after its introduction, 
 begins to bear young, which penetrate the wall of the intestine and 
 make their way actively or by means of the blood-stream, into the 
 muscles, here within fourteen days to develop into spiral worms and to 
 encyst ; they first attain sexual maturity in the intestine of some other 
 warm-blooded animal. This form is maintained by means of the house- 
 rat. Filaria (Dracunculus) medinensis, Guinea-worm, in the subcuta- 
 neous connective tissue of man ; the young form in Cyclops. Mermis, 
 devoid of anus, in the body-cavity of insects, thence to damp earth, where 
 sexual maturity is reached. SphSBrularia bombi, in female humble- 
 bees which survive the winter. Gordius aquaticus, in insect larvae, 
 later in the body-cavity of predatory insects ; then becomes mouthless 
 and sexually mature in water. Anguillula aceti, vinegar-eel, free- 
 living. Tylenehus tritici, in wheat, &c., causing ear-cockle; young 
 form in earth. Dorylaimus, common in mud. 
 
58 VERMES. 
 
 Order 2. Acanthocephata. Endoparasites without mouth or alimentary 
 canal. Possess a retractile hook-bearing proboscis. Sexes separate. A 
 single genus Echinorhynchus. E. gigas in the small intestine of the 
 pig ; the embryo is developed in the larva of the cockchafer. 
 
VERMES. 59 
 
 The systematic position is doubtful of 
 
 Order 3. Chcetognatha. Marine, free-living hermaphrodites with lateral 
 fins, head, cerebral, sub-oesophageal and ventral ganglia. Are entero- 
 ccelic (mesoderm developed from archenteric diverticula). Sagitta ger- 
 manica. S. bipunctata. 
 
60 
 
 Name. 
 
 Dwelling-place of Sexual Form. 
 
 Distomum hepaticum. 
 
 <S in bile-ducts of sheep, other domestic mam- 
 + mals, seldom Man. 
 
 i). crassum. 
 
 c5 ditto, very rarely Man. 
 
 + 
 
 D. lanceolatum. 
 
 ditto. 
 
 + 
 
 D. liBematobium (Bilharzia). 
 
 $ 9 in portal vein, &c., of Man (Abyssinia) ; sel- 
 dom in apes. 
 
 Monostomum flavum. 
 
 <J in water-birds. 
 
 + 
 
 Polystomum integerrimum. 
 
 cJ urinary bladder of frog. 
 
 + 
 
 Diplozoon paradoxum. 
 
 (J gills of freshwater fish. 
 
 + 
 
 Bothriocephalus latus. 
 
 cJ intestine of Man ; rarely cat and dog. 
 
 + 
 
 Bothr. cordatus. 
 
 (J intestine of dog and seal, seldom of Man. 
 
 + 
 
 Triamophorus nodulosus. 
 
 cJ intestine of pike. 
 
 + 
 
 Teenia solium. 
 
 <5 in the small intestine of Man. 
 
 T. saginata (mediocanellata). 
 
 $ in the small intestine of Man. 
 
 + 
 
 T. coenurus. 
 
 <5 in the intestine of sheep-dog. 
 
 -f 
 
 T. echino coccus. 
 
 cj in the small intestine of the dog. 
 
 + 
 
 Ascaris lumbricoides. 
 
 (5 9 in the small intestine of Man, ox, pig. 
 
 Asc. mystax. 
 
 cJ 9 in intestine of cat and dog ; very rarely 
 Man. 
 
 Oxyuris vermicularis. 
 
 c5 9 in large intestine of Man. 
 
 Dochmius duodenalis. 
 
 $ ? in small intestine of Man, gorilla. 
 
 Trichocephalus dispar. 
 
 (5 ? ctecum of Man, also in swine. 
 
 Trichina spiralis. 
 
 c5 9 small intestine of Man, rat, mouse, pig, 
 cat, &c. 
 
 Filaria (Dracunculus) medinensis. 
 
 $ 9 in subcutaneous connective tissue of Man. 
 
 Gordius aquaticus. 
 
 <5 9 m water. 
 
 Rhabdonema nigrovenosa. 
 
 <$ lung parasites of Batrachians. 
 
 + 
 
 Echinorhynchus gigas. 
 
 (J 9 intestine of swine, Man. 
 
 Ech. proteus. 
 
 cJ 9 intestine of freshwater fish. 
 
61 
 
 Young Stages. 7= Intermediate Host. 
 
 Distribution. 
 
 7; embryo (aquatic) bores into Limnseus trun- 
 catulus ; sporocyst - redia - cercaria, the 
 last encysts on grass, &c. 
 
 Europe, N. Africa, N. America, Australia. 
 
 East Asia. 
 
 7; embryo (aquatic) penetrates Planorbis mar- 
 
 Europe and N. America. 
 
 ginatus ; sporocyst -> redia 
 last encysts in Planorbis (?) 
 
 cercaria, the 
 
 7; embryo ciliated ; further history unknown. I Cairo. The Cape. 
 
 7; as Cercaria ephemera in Planorbis. 
 
 
 No 7; larva on tadpole, resembles Gyrodactylus. 
 
 
 No 7; larva solitary (Diporpa). 
 
 
 7; the ciliated embryo appears to pass into a 
 first 7, from thence (by intestine, &c.) into 
 muscles of pike and burbot. 
 
 7; undoubtedly'flslu 
 
 West Switzerland and S. France, Russian Baltic 
 Provinces, Sweden, &c.; rarely Germany, 
 Japan. 
 
 Greenland, Iceland. 
 
 7; encysted in the liver of Cyprinus. 
 
 7; the pig, rarely Man (self-infection), dog, cat. 
 
 Cysticercus cellulosse. 
 
 7; the ox. 
 
 7; as Coenurus cerebralis in the brain of sheep. 
 
 7; domestic animals, more rarely Man. 
 
 Iceland, Europe, India, &c. 
 
 7 probably; (Julus guttulatus ?) ; the eggs pass I Cosmopolite, 
 into water. 
 
 No 7; self-infection. 
 
 No 7; young form (Rhabditis) lives free in I Switzerland, Italy, Egypt, Comoro Islands, 
 mud. | Brazil, Cayenne. 
 
 Apparently no 7; young free-living ? | Widely distributed. 
 
 No 7; the young forms encyst in the infected j 
 animals. 
 
 7; the young form in Cyclops. | Tropics of the Old World, West Indies. 
 
 /; embryos pass into insects, later into pre- 
 datory insects, become sexual in water. 
 
 
 <J ? in damp earth (Rhabditis). 
 
 
 7; pass into cockchafer larvae. | 
 
 7; encyst in Gammarus pulex.. 
 
02 VERMES. 
 
 Class III. Rotatoria (Rotifera). Wheel 
 Animalcules. 
 
 Small unsegmented aquatic animals. Possess a retractile trochal 
 apparatus, a single cerebral ganglion, and two excretory tubes opening 
 into an archiccelic body-cavity ; sexes separate. No vascular system. The 
 male smaller, mostly with a cord-like rudiment of the gut, and mouthless. 
 Summer eggs (parthenogenetic), and winter eggs (fertilized). Rotifer 
 vulgaris (redivivus), trochal disc double. Brachionus with carapace. 
 Hydatina senta. Pedalion, with limb-like appendages. 
 
 Here may be annexed the Gastrotricha, with ciliated ventral surface. 
 Chaetonotus. 
 
 Ray Lankester includes Rotatoria (on the strength of Pedalion), Chtetopoda, 
 and Arthropoda, in a single phylum, Appendiculata, characterized by the pos- 
 session of lateral locomotor appendages. TR. 
 
VERMES. 63 
 
 Class IV. Annelida (Annulata). Kinged Worms. 
 
 Homonomously segmented worms, with brain, ventral chain of ganglia, 
 closed vascular system, and paired nephridia (segmental organs). Typical 
 larval form the trochosphere. 
 
 Order 1. Archiannelida, small marine worms, devoid of setae and para- 
 podia. Body-wall without a circular layer of muscle. Polygordius 
 (with Loven's larva). Protodrilus. Histriodrilus (Histriobdella). 
 Dinophilus. 
 
 Order 2. Chcetopoda, bristle- worms. Free-living forms, with a more or 
 less prominent praestomium, and paired groups of setaa. Body-cavity 
 entirely enteroccelic ; vascular system of a series of closed tubes. 
 
 Polychseta, marine, with numerous setse imbedded in parapodia. 
 Antennae, palpi, cirri, and gills generally present. Sexes usually separate, 
 and development with a metamorphosis. Nereis. Syllis. Aphrodite, 
 sea mouse. Polynoe. Arenicola piscatorum, lug-worm, Terebella, 
 and Serpula, with tubes. Myzostoma, a small much-modified ecto- 
 parasite, occurring on Crinoids. 
 
 Oligochseta, fresh.- water or terrestrial, with relatively few setse. 
 Devoid of antennae, palpi, cirri, and gills. Hermaphrodites with direct 
 development. Lumbricus terrestris (agricola), earthworm. Lumbri- 
 culus variegatus. Nais proboscidea. Tubifex rivulorum. 
 
 Order 3. Hirudinea (Discophora), leeches. Aquatic hermaphrodite 
 ectoparasites divided into annuli more numerous than the true segments, 
 some of which are fused posteriorly into a terminal sucker, dorsal to 
 which is the anus. Mouth anterior, ventral, and surrounded by a sucker. 
 Setae and parapodia absent. Body-cavity in the form of vascular spaces 
 in the connective tissue which occupies the space between body-wall and 
 gut. Piscicola geometra (on freshwater fish) and Clepsine with pro- 
 trusible proboscis. Hirudo medicinalis (var. officinal is), medicinal 
 leech, with three toothed jaws ; attains sexual maturity in about three 
 years. 
 
70 VERMES. 
 
 Class V. Gephyrea. 
 
 Unsegmented marine worms, more or less cylindrical in form. There 
 is a proboscis or the anterior end of the body is invaginable. Nervous 
 system of a circumcesophageal loop (sometimes with a brain) and a 
 ventral non-ganglionated cord. A large enterocoelic body-cavity, usually 
 communicating with the exterior by a small number of anterior nephridia. 
 Sexes separate. 
 
 A r m a t a (Chsetif era), with a proboscis and two ventral setae. Anus 
 terminal. Echiurus. Thalassema. Bonellia viridis (dwarf planarian- 
 like male, parasitic in the female). 
 
 Inerma (Achseta), with invaginable anterior end, and no seta?. 
 Sipunculus nudus. Phascolosoma vulgare. Priapulus. The two 
 first with dorsal anterior anus. 
 
 See note on p. 39. 
 
ECHINODERMATA. 73 
 
 Phylum II. ECHINODERMATA. 
 
 Radial marine animals with pentamerous symmetry (the larvae bilater- 
 ally symmetrical), and with calcifications in the skin. A water- vascular 
 system typically composed of a ring-canal with connected stone-canal, 
 Polian vesicles, tentacular tubes, and five ambulacral canals. A nerve- 
 ring with five main trunks, radial in position. After complete (often 
 regular) cleavage of the fertilized ovum a blastula with segmentation- 
 cavity is formed, and from this a gastrula with the two germinal layers, 
 ectoderm (epiblast) and endoderm (hypoblast). The mesoderm and 
 water- vascular system are formed from diverticula of the archenteron. 
 The blood-vascular system is developed from spaces in the mesodermic 
 tissue. Body-cavity an enteroccele. A metamorphosis. 
 
74 ECHINODERMATA. 
 
 Class I. Crinoidea. Sea Lilies. 
 
 Spherical, goblet- or cup-shaped ; fixed when young or permanently 
 by a jointed calcareous stalk. Possess branched arms, usually furnished 
 with pinnules. A nervous system on the aboral side of the body, in addi- 
 tion to the ordinary one. Groups of tentacles are formed by side 
 branches of the radial water-vascular vessels. No madreporic plate or 
 stone- canal, but water-tubes opening into the enterocoelic body-cavity, 
 which again communicate by water-pores with the exterior. Many fossil 
 forms ; recent examples mostly inhabitants of the deep sea. Encrinus 
 liliiformis from the Muschelkalk. Pentacrinus caput Medusse, recent. 
 Comatula (Antedon) rosacea, feather star, stalked when young, later 
 on free. 
 
ECHINODERMATA. 75 
 
 Class II. Asteroidea. Star-fish. 
 
 Body star-shaped or pentagonal; the tube-feet on the ventral surface. 
 
 Order 1. Stellerida. Digestive caeca, extending into the arms; anus 
 dorsal when present. Tube-feet situated in ambulacral grooves, usually 
 end in suckers ; maclreporic plate dorsal and interradial. Some develop 
 directly in a brood-cavity of the mother, the rest with a metamorphosis 
 (Bipinnaria, Brachiolaria). PedicellariaB. Asterias (Uraster) rubens, 
 common star-fish, and A. glacialis, tube-feet in four rows. Solaster 
 papposus, sun-star, generally with thirteen arms. Astropecten auran- 
 tiacus, tube-feet without suckers, in two rows. Asterina gibbosa, 
 pentagonal. 
 
 Order 2. Ophiurida, brittle stars. Arms cylindrical, sharply marked 
 off from body; stomach without caecal prolongations. Ambulacral 
 furrows covered in by dermal plates, so that the tube-feet, which are 
 devoid of suckers, protrude at the sides of the arms. No anus ; no pedi- 
 cellarise (as a rule). Madreporic plate ventral, usually fused to an oral 
 plate. Larval form a Pluteus. Ophiothrix fragilis and Amphiura 
 squamata, viviparous. Astrophyton arborescens with soft-skinned 
 ventral surface, branched arms, and pedicellarise. 
 
ECHINOPERMATA. 77 
 
 Class III. Echinoidea. Sea-urchins. 
 
 Body rounded or flattened. Twenty rows of calcareous dermal plates 
 make up a strong test, perforated by rows of tube-feet, and bearing 
 movable spines and pedicellarise. Tube-feet with suckers. Blood- 
 vascular system often well developed. The genital pores lie at the 
 vertex (periproct) of the shell on interradial genital plates one of which 
 is the madreporic plate; radial ocular plates alternate with the preceding. 
 The mouth of the gastrula persists as the anus. Development with a 
 Pluteus larva. Many occur fossil. * 
 
 Order 1. Regularia. Spherical, with masticatory apparatus (Aristotle's 
 lantern) of five oral teeth, &c. Echinus melo, Toxopneustes, Stron- 
 gylocentrotus lividus, all with oral gills; Cidaris, without oral gills. 
 Calveria (Asthenosoma), a deep-sea form with flexible test. 
 
 Order 2. Clypeastroidea, shield-urchins. Irregular, with central 
 mouth and masticatory apparatus ; around the aboral pole a five-leaved 
 ambulacral rosette ; anus excentric. Clypeaster ; Mellita with fenes- 
 trated shell. 
 
 Order 3. Spatangoidea, heart-urchins. Irregular with excentric 
 mouth and anus; no masticatory apparatus. Spatangus purpureus 
 with four genital glands and openings. 
 
ECHINODERMATA. 79 
 
 Class IV. Holothuroidea. Sea-cucumbers. 
 
 Elongated forms with tough muscular body- wall containing calcareous 
 bodies, and with a circlet of retractile oral tentacles. Gullet sur- 
 rounded by a ring of calcareous ossicles. The madreporic plate external 
 in the larvae and also in many adult Elasipoda, but directed into 
 the body-cavity in other adults. A blood-vascular system. Larva 
 (Auricularia) most like that of Stellerida. 
 
 Order 1. Pedata, with respiratory trees, and external ambulacral ap- 
 pendages (tube-feet, papillae), which are arranged in rows or scattered. 
 Sexes separate. 
 
 Dendrochirotae, arborescent tentacles ; five retractors to the 
 pharynx ; generative caeca in two bundles. Cucumaria Planci, ten 
 tentacles. 
 
 Aspidochirotse, 20-30 shield-shaped tentacles, by means of which 
 the food is shovelled into the mouth ; only one bundle of generative cfceca. 
 Holothuria tubulosa, 20 tentacles; Miilleria, 25 tentacles, five cir- 
 cumanal plates. 
 
 Order 2. Elasipoda, all primitive deep-sea forms, with reduced or 
 rudimentary calcareous ring ; without respiratory trees or ciliated funnels ; 
 stone-canal often opening to the exterior. Sexes separate. Move by 
 creeping, and the dorsal and ventral surfaces sharply marked off in 
 consequence ; tube-feet limited to the latter. Deima, the calcareous 
 ring a brittle network, long stiff papillae on the back. 
 
 Order 3. Apoda, without tube-feet or papillae. 
 
 Pneumonophora, with respiratory trees. Molpodia. 
 
 Apneumona, ciliated funnels in the mesentery instead of respiratory 
 trees ; mostly hermaphrodite. Chirodota, with calcareous wheels in the 
 skin. Synapta digitata, calcareous ossicles in the form of plates and 
 anchors. 
 
ARTHROPODA. 81 
 
 Phylum III. ARTHROPODA. 
 
 The heteronomously segmented body with jointed lateral appendages, 
 brain and ventral ganglionated chain, and chitinous exoskeleton. 
 Vascular system, when present, not closed, but communicates with the 
 irregular spaces which make up the body-cavity. Enterocoelic spaces 
 inconspicuous. Sexes almost always distinct. Development frequently 
 with metamorphosis ; sometimes parthenogenesis. 
 
 See note, p. 62. 
 
ARTHROPODA. 85 
 
 Class I. Crustacea. 
 
 Aquatic forms usually breathing by gills, with two pairs of antennae, 
 with paired limbs on the thorax and usually on the abdomen. 
 
 On the head two pairs of antennae, a labrum, two mandibles with 
 palps, and two pairs of maxillae. The thorax bears (at least three) pairs 
 of appendages, of which some of the most anterior are frequently modified 
 into foot-jaws (maxillipedes), while the following vary in form and 
 function, as do the abdominal appendages. The typical larval form of 
 the lower Crustaceans is the Nauplius, of the higher the Zoea. 
 
 GROUP A. ENTOMOSTRACA. Small forms of simple structure, with a 
 variable number of segments and appendages. Generally a Nauplius 
 larva. 
 
 Order 1. Phyllopoda. With four or more pairs of leaf -shaped lobed 
 swimming feet, and generally a carapace or bivalve shell. Mostly in 
 freshwater lakes. 
 
 Branchiopoda, relatively large, with saccular gills attached to 
 the numerous swimming feet. Elongated heart. Generally a nauplius 
 larva. Branchipus stagnalis. Apus cancriformis, male very rare. 
 
 Cladocera, water fleas, laterally compressed and imperfectly seg- 
 mented, with large locomotor second antennae, generally with a bivalve 
 shell. Heart short. Summer and winter eggs ; parthenogenesis. Rarely 
 a larva. Daphnia pulex. Leptodora, nauplius from winter eggs. 
 
 Order 2. Ostracoda. With unsegmented body, rudimentary abdomen, 
 and seven pairs of appendages. Enclosed in a bivalve shell. Cypridina 
 serrato-striata, fossil, C. mediterranea, recent. Cypris fusca. 
 
 Order 3. Copepoda. Usually well segmented ; devoid of a shell. 
 Four to five pairs of biramous swimming feet on the thorax, abdomen 
 without appendages. Cyclops coronatus, without heart. Common in 
 fresh water. Ergasilus, Chondracanthus, Caligus, Lernsea, Lernse- 
 ocora, Achtheres, and Anchorella, degenerate parasites with piercing 
 or sucking mouth-parts and stunted abdomen. Argulus foliaceus on 
 the carp and stickleback ; the second maxillae are modified into suckers. 
 
 Order 4. Cirripedia. Sessile hermaphrodites with a duplicature of the 
 skin (and a shell). Lepas anatifera, ship barnacle. Balanus tin- 
 tinnabulum, acorn barnacle, fossil and recent. 
 
 As Rhizocephala or Suctoria we group together the parasitic 
 forms in which segmentation and gut are absent. Peltogaster paguri, 
 Sacculina carcini. 
 
ARTHROPODA. 87 
 
 GROUP B. LEPTOSTRACA. Small marine Crustaceans, with five cephalic, 
 eight free thoracic, and eight abdominal segments; a forked telson. 
 Anterior part of body enclosed in a bivalve shell. Eight pairs of folia- 
 ceous swimming-feet attached to the thorax. Eyes compound, on short 
 stalks. No larval stage. Only known genus, Nebalia. 
 
 The Crustacean head is often regarded as composed of six segments ; the 
 telson is possibly a segment TR. 
 
88 ARTHROPODA. 
 
 GROUP C. MALACOSTRACA. Crustaceans with five cephalic, eight 
 thoracic, and six abdominal segments; a telson. 
 
 Order 1. Arthrostmca (Edriophthalmata). Seven (rarely six) free 
 thoracic segments and sessile lateral eyes. No cephalothoracic [shield 
 or larval form. 
 
 Amphipoda, body laterally compressed; gills on the thoracic 
 limbs. Gammarus pulex. Talitrus locusta, sand-hopper. Phro- 
 nima. Caprella linearis. Cyanms ceti. 
 
 I s o p o d a, with vertically flattened body and gill-bearing abdom- 
 inal appendages. Asellus aquaticus, Oniscus murarius, wood-louse, 
 Armadillo vulgaris ; Tanais dubius, with two kinds of male. 
 
 Order 2. Thoracostraca. A cephalothoracic shield and compound eyes 
 which are generally stalked. 
 
 Cumacea, 4-5 free thoracic segments, two pairs of foot-jaws, no 
 abdominal appendages in the female, sessile eyes. Cuma. 
 
 S t o m a t o p o d a, short cephalothoracic shield, five pairs of foot-jaws, 
 gills abdominal. Squilla mantis, locust-crab. 
 
 S c h i z o p o d a, a large cephalothoracic shield, and eight pairs of 
 biramous thoracic appendages. Mysis, opossum-shrimp, with otocysts 
 in the tail-flaps. 
 
 D e c a p o d a, large cephalothoracic shield. Thoracic appendages con- 
 sist of three pairs of foot-jaws, and five pairs of uniramous leet: (a) 
 Macrura with long abdomen; Palaemon, prawn, Crangon vulgaris, 
 shrimp, Astacus fluviatilis, cray-fish, Homarus vulgaris, lobster, 
 Palinurus vulgaris, rock-lobster, Nephrops Norvegicus, Norway 
 lobster, Pagurus Bernhardus, hermit-crab : (6) Brachyura with short 
 abdomen ; Cancer pagurus, edible crab, Carcinus mcenas, shore-crab. 
 
90 ARTHROPODA. 
 
 Class II. Arachnida. 
 
 Wingless Arthropoda with a cephalothorax, and four to six pairs of 
 legs. 
 
 GROUP A. ARACHNIDA BRANCHIATA (Gigantostraca, Poecilopoda). 
 Aquatic gill-bearing Arachnidans. 
 
 Order 1. Xiplwsura. A shield-shaped cephalothorax, with a single 
 pair of chelate appendages in front of the mouth, and five pairs of legs 
 with masticatory bases behind the mouth. The abdomen bears six pairs 
 of appendages, of which the first are united to form a genital operculum, 
 while the remainder are lamellar with numerous gill-folds. A spine- 
 like telson. Two large facetted frontal eyes, and two central dorsal 
 eyes. Mostly fossil. Limulus, first occurs in the lithographic slates 
 (Middle Oolite). L. polyphemus, recent. 
 
 Order 2. Eurypterina. Extinct forms with small cephalothoracic shield, 
 one pair of praeoral appendages, and four pairs of legs with masticatory 
 bases around the mouth. Abdomen of twelve segments, devoid of 
 abdominal appendages (?), and ending in a broad telson. Eurypterus 
 pygmseus, Devonian. 
 
 Order 3. Trilobita. Extinct forms with a cephalothoracic shield, no 
 prseoral appendages, but four pairs around the mouth. Abdomen bear- 
 ing appendages, and with a segmented anterior region. Calymene 
 Blumenbachii. Phacops. 
 
92 ARTHROPODA. 
 
 GROUP B. ARACHNIDA TRACHEATA. Chiefly terrestrial Arachnidans, 
 with chelicera? (falces), pedipalpi, and 4 pairs o"f legs ; but abdomen usu- 
 ally limbless. Breathe air by trachea, lung-books, or the skin. 
 
 Order 1. Acarina, mites. Abdomen fused with rest of body ; respira- 
 tion by skin or trachea?. Demodex folliculorum, hair-sheath mite, 
 hermaphrodite. Sarcoptes scabiei, itch-mite, with suctorial cone and 
 pincer-shaped chelicera?. The females dig deep burrows in the epidermis, 
 in which they live ; hexapod larvse. Tyroglyphus siro, cheese-mite. 
 Ixodes ricinus, with trachea? and two stigmata. Hydrachna cruenta. 
 the six-legged larva? parasitic on aquatic insects. 
 
 Order 2. Pycnogonida (Pantopoda). Marine forms of doubtful affinities, 
 with rudimentary abdomen, and four pairs of walking legs. Cutaneous 
 respiration. Pycnogonum littorale. 
 
 Order 3. Tardigrada, water-bears. Minute aquatic hermaphrodites, 
 with piercing and sucking mouth parts, and four pairs of short walking legs. 
 Devoid of circulatory and respiratory organs. Macrobiotus Hufelandii. 
 
 Order 4. Linguatulidce. Parasites without trachea 1 . Sexes separate. 
 Pentastomum tsenioides in the nasal cavities and frontal sinus of the 
 wolf and dog. The embryos pass on to herbage and with this into the 
 stomachs of the hare and rabbit, also of man, perforate the intestinal wall, 
 encyst themselves in the liver, and lastly reach the final host with the 
 flesh. 
 
 Order 5. Araneida, spiders. With poison-glands in the subchelate 
 chelicera?, pedipalps ambulatory, abdomen unsegmented. Two or four 
 lung-books, six or four spinning papillae. Four lung-books : Mygale 
 avicularia. Cteniza csementaria makes tubes with trap doors in the 
 earth. Two lung-books : Salticus. Lycosa tarantula. Tegenaria 
 domestica, house spider. Epeira diadema, garden spider. 
 
 Order 6. Phalangidce, harvestmen. With chelate chelicera?, slender legs, 
 and abdomen of six segments. Tracheate. Phalangium opilio. 
 
 Order 7. Pedipalpi (Phrynidre). Clawed chelicer.-e, large pedipalpi, 
 slender first pair of legs, and two pairs of lung-books. Abdomen with 
 eleven to twelve segments. Phrynus. 
 
 Order 8. Scorpionidce, scorpions. With chelate chelicera?, large chelate 
 pedipalpi, four pairs of lung-books, and poison claw at the end of the 
 tail. Abdomen with twelve segments and a telson ; abdominal append- 
 ages as genital operculum and pectines. Lateral and central eyes. Vivi- 
 parous. Scorpio Europseus. Androctonus. 
 
 Order 9. Pseudoscorpionidce (Chernelida?). Small forms with large 
 chelate pedipalpi and a broad flattened abdomen of 10-11 segments. 
 Breathe by trachea?. Chelifer cancroides. Chernes. 
 
 Order 10. Solifugce (Solpuga?). Head distinct from the thorax, which 
 has three segments ; abdomen with nine segments. Chelate chelicera? 
 and leg-like pedipalpi. Breathe by trachea?. Galeodes (Solpuga) 
 araneoides. 
 
94 ARTHROPODA. 
 
 Class III. Protracheata (Onychophora, 
 Peripatidea). 
 
 Tracheates with vermiform body, two antenn.ce, a pair of jaws, a pair 
 of oral papillae, and numerous pairs of imperfectly jointed limbs. 
 Stigmata numerous and scattered. Each foot-bearing segment with a 
 pair of nephridia. A single genus, Peripatus, which appears to be 
 most closely allied to the Myriapods. 
 
96 ANTHROPODA. 
 
 Class IV. Myriapoda. 
 
 Terrestrial Tracheates with numerous similar body-segments, a dis- 
 tinct head, a pair of antennae, three pairs of jaws, and numerous paired 
 legs. 
 
 Order 1. Chilopoda, centipedes. Body depressed, and only one pair of 
 legs to each segment. A single posterior genital opening. Scolopendra 
 morsitans. Geophilus electricus. Lithobius forficulatus. 
 
 Order 2. Chilognatha, millipedes. Body rounded, and two pairs of 
 legs to each segment. Genital openings on the basal joints of the second 
 or third pair of limbs. Julus sabulosus. Glomeris marginata. 
 
ARTHROPODA. 99 
 
 Class V. Insecta (Hexapoda). 
 
 Tracheates with distinct head, thorax and abdomen. The head bears 
 a pair of antennae, compound eyes, palpless mandibles, and two other 
 pairs of jaws ; the three thoracic segments bear three pairs of legs, and 
 commonly one or two pairs of wings; abdomen usually limbless. At 
 most ten pairs of stigmata. Sexes separate. 
 
 A. INCOMPLETE METAMORPHOSIS. 
 
 Order 1. Orthoptera. Jaws adapted for biting; two pairs of dissimilar 
 wings. Forficula, earwig. Periplaneta (Blatta) orientalis, cock- 
 roach. Phyllium, Phasma, Bacteria calamus, and Mantis religiosa 
 exhibit mimicry. (Edipoda migratoria, passage locust, Locusta 
 viridissima, grasshopper. Gryllotalpa vulgaris, mole-cricket, Gryllus 
 campestris, GK domesticus, house-cricket. 
 
 Order 2. Thysanura (Aptera), wingless. Body hairy or scaly. Mouth- 
 parts rudimentary. Tracheae may be absent. Podura. Lepisma 
 saccharina. Campodea staphylinus with foot-stumps on the anterior 
 abdominal segments. 
 
 Order 3. Pseudoneuroptera. Mouth-parts biting; wings membranous, 
 alike. Termes lucifugus, white ant. Thrips. Amphibiotic forms 
 (the larvae aquatic, with tracheal gills): Ephemera vulgata, May-fly. 
 Agrion puella, -ffischna grandis, Libellula vulgata, dragon flies. 
 
 Order 4. Hemiptera. Mouth-parts piercing or sucking. Coccus cacti, 
 cochineal insect, on Opuntia. Aspidiotus nerii, on Oleander. Aphis 
 rosae with two honey-tubes ; parthenogenesis in spring and summer. 
 Phylloxera vastatrix, vine-louse, (from the winter-eggs wingless forms 
 emerge in the spring, which destroy the vine-roots and reproduce par- 
 thenogenetically; later generations cause leaf -galls; the winged genera- 
 tion of late summer produce, parthenogenetically, dimorphic eggs from 
 which large females and small asplanchnic males are hatched). Cicada, 
 the abdomen of the male with a stridulating organ. Acanthia (Cimex) 
 lectularia, bed-bug. Nepa cinerea, water-scorpion. Pediculus ca- 
 pitis, head-louse. Phthirius vestimenti ; P. pubis. 
 
 B. COMPLETE METAMORPHOSIS. 
 
 Order 5. Neuroptera. Biting mouth-parts, free prothorax, and two 
 pairs of similar membranous netted wings. Hemerobius perla, lace- 
 fly. Myrmeleon formicarius, ant-lion. 
 
 Order 6. Trichoptera (Phryganidae). Wings covered with hairs and 
 scales ; the larvae aquatic, in tubular cases. Phryganea, caddis-fly. 
 
 Order 7. Strepsiptera. Parasites, with rudimentary mouth-parts, the 
 front wings of the male rudimentary and twisted, the female wingless 
 and vermiform. Xenos vesparum. Stylops mellitse. 
 
ARTHROPODA. 101 
 
 Order 8. Diptera. Mouth-parts sucking or piercing ; front wings 
 membranous, hind wings reduced to halteres. Pupipara, the female 
 produces larvae ready to become pupae. Hippobosca equina. Musca 
 domestica, house-fly. M. vomitoria, blue-bottle. Sarcophaga car- 
 naria, flesh-fly, viviparous. Gastrus equi, bot-fly, larva in the wall 
 of the horse's stomach. Tabanus bovinus, gad-fly. Nemocera or 
 Tipulariae: Corethra plumicornis, larva with four tracheal bladders. 
 Cuiex pipiens, gnat, the female stings. Cecidomyia, Hessian fly, and 
 Miastor, viviparous. Tipula, crane-fly. 
 
 Order 9. Aphaniptera, fleas. Mouth-parts sucking and piercing. 
 Wings rudimentary. Pulex irritans, common flea. 
 
 Order 10. Coleoptera, beetles. With biting mouth-parts, horny front 
 wings (elytra), and freely movable prothorax. Legs with five- rarely with 
 four-jointed tarsi. Coccinella septempunctata, ladybird. Cerambyx 
 heros. Meloe proscarabseus, oil beetle. Lytta vesicatoria, Spanish 
 fly. Lampyris noctiluca, glow-worm. Lucanus cervus, stag beetle. 
 Melplontha vulgaris, cockchafer. Staphylinus. Hydrophilus piceus. 
 Dytiscus marginalis. 
 
 Order 11. Hymenoptera. Mouth -parts biting (or licking) ; four mem- 
 branous wings. Terebrantia, female with an ovipositor. Tenthredo, 
 saw-fly. Cynips quercus folii, gall-fly. Ichneumon. Aculeata, 
 usually with a sting ; young helpless. Formica rufa, fusca, rufescens, 
 flava, &c., ants. Vespa vulgaris, wasp. Apus mellifica, honey-bee, 
 Bombus terrestris, humble-bee. 
 
 Order 12. Lepidoptera, moths and butterflies. With sucking mouth- 
 parts, the maxillae forming a rolled proboscis, and four scaly wings. 
 Irregular parthenogenesis in several. Tinea, clothes-moth (one of the 
 Microlepidoptera). Geometra, geometer. Noctua. Bombyx mori, 
 silkworm moth, Psyche helix, both parthenogenetic. Sphinx, hawk- 
 moth. Sesia apiformis, like a hornet (mimicry). Picris brassicae, 
 white cabbage butterfly. Kallima paralecta and K. inachis, both 
 extremely like dry leaves when at rest. 
 
MOLLU8COIDEA. 105 
 
 Phylum IV. MOLLUSCOIDEA. 
 
 Sedentary, almost exclusively marine animals, with a lophophore 
 bearing ciliated tentacles, an epistome, house or bivalve shell, and one 
 or several ganglia. Prseoral region much reduced or absent. Mouth and 
 anus generally approximated. Body elongated at right angles to the oro- 
 anal axis. 
 
 See note, p. 39. 
 
 Class I. Polyzoa (Bryozoa). 
 
 Small forms, usually colonial, and with sexes united. Development 
 with a metamorphosis. ^/r 
 
 Order 1. Vermiformia. Social Polyzoans enclosed in leathery tubes ; 
 lophophore horseshoe-shaped. Nervous system as a ring round the mouth 
 and a body-nerve. A system of blood-vessels, enterocoelic body-cavity, 
 and two nephridia. Only known genus Phoronis, with Actinotrocha 
 larva. 
 
 Order 2. Eupolyzoa. Almost all colonial. Contained in cells formed 
 by the thickened cuticle. Nervous system as a single ganglion. No 
 vascular system. Budding always occurs. 
 
 Endoprocta. Anus within the lophophore, which can only be 
 partially retracted. No proper body-cavity. Nephridia. Pedicellina 
 echinata, colonial. Loxosoma, non-colonial. 
 
 Ectoprocta: anus outside the lophophore, which can be com- 
 pletely retracted. An enterocoelic body-cavity. Oristatella, Pluma- 
 tella, Alcyonella, in fresh water, with horseshoe-shaped lophophore ; 
 statoblasts. Tentacles in a circle in most marine forms : Eetepora. 
 Membranipora, Flustra, Alcyonidium. 
 
MOLLUSCOIDEA. 109 
 
 Class II. Brachiopoda. 
 
 All marine, with bivalve shell (valves unequal, but symmetrical) and 
 lophophore (horseshoe-shaped or in the form of two spiral arms). There 
 is an enteroccelic body-cavity, and two or four nephridia. Larva vermi- 
 form. Mostly fossil. 
 
 Order 1. Ecardines, shell hingeless ; an anus. Lingnla antiqua. 
 L. anatina, recent. 
 
 Order 2. Testicardines, shell with hinge and (usually) a calcareous 
 support for the arms ; no anus. Productus, fossil ; E-hynchonella, 
 with short two-limbed, Spirifera (fossil) with spiral, Terebratula with 
 loop-shaped arm-support. Argiope. 
 
MOLLUSCA. 113 
 
 Phylum V. MOLLUSCA. 
 
 Unsegmented animals, with a soft body, mantle and dorsal shell 
 (usually), muscular ventral foot, large digestive gland (liver), and open 
 vascular system. Enteroco3le represented by pericardial cavity, which 
 typically communicates with exterior by a pair of nephridia. Cerebral, 
 pleural, and pedal ganglia. Larva (Veliger) usually with a velum. 
 
 Subphylum A. Lipocephala (Acephala). 
 
 Head-region rudimentary and devoid of eyes. No odontophore. 
 
 Class I. Lamellibranchiata. 
 
 With bilobed mantle and shell (valves equal but unsymmetrical), 
 large gill-plates (in most); two pairs of labial palps; paired nephridia 
 (organs of Bojanus), auricles, digestive gland and gonads; sexes generally 
 separate. 
 
 Order 1. Asiphonida, no siphons. With one adductor muscle : Pecten 
 Jacobseus, clam, Ostrea edulis, oyster, both hermaphrodite. With 
 two adductors : Meleagrina margaritifera, pearl-mussel. Mytilus 
 edulis, edible mussel. Lithodomus dactylus. Trigonia. Unio pic- 
 torum, Anodonta cygnsea, freshwater mussels (the free larva, "glochi- 
 dium," parasitic on fishes). 
 
 Order 2. Siphonida, siphons ; two adductor muscles. Cardium edule, 
 cockle. Cyclas cornea in fresh water. Venus. Solen Aspergillum, 
 with tubular shell. Teredo navalis, ship-worm. 
 
118 MOLLUSC A. 
 
 Subphylum B. Glossophora. 
 
 Head-region developed. An odontophore. 
 
 Class I. Scaphopoda. 
 
 Possess an ill-developed head, a trifid foot, and a curved tubular shell. 
 Two bunches of gill-filaments, but no heart or eyes. Sexes separate and 
 gonad unpaired. Dentalium. 
 
MOLLUSCA. 121 
 
 Class II. Gastropoda. 
 
 The foot usually forms a simple sole-like ventral expansion. 
 
 A. GASTROPODA ISOPLEUBA. Forms exhibiting bilateral sym- 
 metry in the external form and in the arrangement of the auricles, 
 ctenidia (gills), nephridia, genital ducts and nerve-cords. Anus posterior. 
 Ganglia ill-developed. 
 
 Order 1. Solenogastres (Amphineura). Marine worm-like Molluscs 
 with foot absent or rudimentary, and the body covered by calcareous 
 spicules. Proneomenia. Neomenia. Chaetoderma. 
 
 Order 2. Polyplacophora. Eight calcareous plates along the back. 
 Chiton squamosus. 
 
 B. GASTROPODA ANISOPLEURA. Head and foot bilaterally sym- 
 metrical, but the visceral hump and mantle have undergone twisting 
 so that the anus, nephridial opening, and genital opening are shifted 
 more or less to the front. Generally a univalve shell, and a single 
 auricle, ctenidium, nephridium, and genital duct. 
 
 Order 1. Streptoneura (Prosobranchia). Visceral nerve-loop twisted ; 
 gills in front of the heart ; sexes separate. Patella, limpet (both 
 ctenidia aborted, secondary gills), Fissurella and Haliptis with both 
 ctenidia and two auricles ; all three with paired nephridia. Trochus 
 (rhipidoglossate). Janthina ptenoglossate). Murex, Buccinum, whelk, 
 and Purpura lapillus (rhachiglossate). Conus (toxoglossate). The fol- 
 lowing are taenioglossate : Cyclostoma elegans (lung-breathing), Palu- 
 dina vivipara, river-snail, Valvata (^ ) all fresh water : Cypraea, 
 cowry, Strombus ; Entoconcha mirabilis, parasitic in Synapta ; Am- 
 pullaria, with gill- and lung-chamber. 
 
 These forms are closely allied to the pelagic taenioglossate Heteropoda 
 (Natantia) with fin-like foot : Bellerophon, fossil ; Carinaria, Atlanta. 
 
 Order 2. Euthyneura. Visceral nerve-loop not twisted. Hermaph- 
 rodite. 
 
 (a) Opisthobranchia, genital openings on the side of the body ; 
 the branchial veins open behind the ventricle into the auricle ; larva 
 with operculate shell, and velum. Shell usually absent in the adult : 
 Aplysia, Pleurobranchus, Bulla (tectibranchs) : Phyllirhoe, Tethys, 
 Doris, .ffiolis, Rhodope (nudibranchs). Elysia (saccoglossate). 
 
 (b) P u 1 m o n a t a, hermaphrodites with a lung-chamber : Pul. basom- 
 matophora, eyes at base of two non-invaginable tentacles: Lymnaeus 
 stagnalis, pond-snail, L. tmncatulus, Planorbis corneus, trumpet- 
 snail. Pul. stylommatophora, eyes at tips of two invaginable tentacles : 
 Arion ater, black slug ; Limax agrestis, garden slug, L. flavus, cellar 
 slug; Helix aspersa, garden snail, H. pomatia, Koman snail, H. 
 nemoralis, hedge snail. 
 
126 MOLLUSCA. 
 
 Class III. Pteropoda. 
 
 (Form a transitional group to Cephalopoda.) 
 
 Marine hermaphrodite Molluscs, devoid of ctenidia, with the mid-foot 
 produced into a pair of wing-like fins. Visceral hump large, and ex- 
 hibiting secondary bilateral symmetry ; anal, genital, and nephridial 
 apertures anterior and lateral. 
 
 Order 1. Thecosomata, with shell; the fins not sharply marked off; 
 a mantle-cavity, often containing branchial folds : Hyalea tridentata, 
 Cymbulia, Tentaculites (fossil). 
 
 Order 2. Gymnosomata, without shell ; fins sharply marked off ; no 
 mantle-cavity. Tentacles on the head. Larva with a zone of cilia: 
 Clio borealis. Pneumodermon, two arms covered with suckers. 
 
MOLLUSCA. 129 
 
 Class IV. Cephalopoda (Siphonopoda). 
 
 Marine ; fore-foot united with head and forming tentacles or arms 
 surrounding the mouth ; mid-foot funnel-like ; sexes separate. A large 
 visceral hump and a mantle cavity containing two or four ctenidia and 
 the anal, genital, and paired nephridial apertures. Chromatophores in 
 the skin. 
 
 Order 1. Tetrabranchiata, two pairs of ctenidia and nephridia, numerous 
 sheathed tentacles without suckers, and an external chambered shell. 
 Funnel incompletely closed ; no ink-bag. 
 
 Nautili dse, septa of the shell concave, siphon central : Orthoceras 
 and Phragmoceras, fossil ; Nautilus pompilius, pearly nautilus, recent. 
 
 AmmonitidaB, septa much folded at their edges, siphon external ; 
 all fossil : Goniatites, Ammonites (with aptychus and anaptychus), 
 Ceratites nodosus, Baculites, Toxoceras, Hamites. 
 
 Order 2. Dibranchiata, a single pair of ctenidia and nephridia, eight or 
 ten arms covered with hooks or suckers, a completely closed funnel and 
 an ink-bag. 
 
 Decapod a, ten arms, two of them much elongated ; suckers stalked 
 and with a horny ring. Body with two lateral fins, shell internal: 
 Belemnites (fossil). Spirula. Sepia officinalis, cuttlefish. Loligo 
 vulgaris, squid. Sepiola vulgaris. Onychoteuthis. 
 
 Octopoda, eight arms, suckers unstalked and without a horny ring, 
 no internal shell, mantle cavity without a cartilaginous closing apparatus. 
 Octopus vulgaris, Eledone moschata. Argonauta argo, paper nautilus; 
 the female large, with a thin boat-shaped shell, secreted by the two dorsal 
 arms ; male small, without shell, and with one arm hectocotylized. 
 
CHORD ATA. 135 
 
 Phylum VI. CHORDATA. 
 
 Coelomate animals with the neural and haemal surfaces dorsal and 
 ventral respectively. At some stage or other a cellular supporting rod, 
 the notochord, underlies the central nervous system for part or all of its 
 extent, and the pharynx is perforated by two or more gill-slits. 
 
 The term Vertebrata is often applied in a wide sense to this phylum. All 
 other animals can then be lumped together under the name Invertcbrata. 
 
 Subphylum A. Hemichorda. 
 
 Chordata with a short notochord mainly situated in the prsestomium. 
 Balanoglossus, a worm-like marine form with prseoral contractile pro- 
 boscis, numerous paired gill-slits, and a branchial skeleton. Central 
 nervous system closely connected with the skin, and heart dorsal to noto- 
 chord. Mouth ventral, anus terminal. Body-cavity an enterocrele. Tor- 
 naria larva, presenting resemblances to Echinoderms, or Bateson's larva 
 with posterior ciliated ring. Generally placed near the Echinoderms in 
 a special group, Enteropneusta. 
 
 Cephalodiscus and Rhabdoplenra are generally placed in the Poly- 
 zoa, as a sub-group Pterobranchia. Two gill-slits and a small notochord 
 have been found in the former. 
 
138 CHORD AT A. 
 
 Subphylum B. Urochorda (Tunicata). Ascidians. 
 
 Marine hermaphrodites, usually of sac- or cask-shaped form. An ex- 
 ternal test of gelatinous or cartilaginous nature. Oral and atrial aper- 
 tures. The first section of the gut is a pharynx perforated by gill-slits 
 (branchial sac). Heart tubular and reversible. Asexual reproduction 
 common, colonies being formed by budding. 
 
 In simple instances, e.g. Ascidia, the development shows great har- 
 mony with that of Amphioxus. After complete cleavage a gastrula is 
 formed by embolic invagination. From the ectoderm a dorsal neural 
 tube is developed, while a notochord (urochord) arises from the posterior 
 part of the archenteron. The tailed larva exhibits metameric segmenta- 
 tion, but later on becomes an unsegmented animal by loss of the tail 
 (with notochord), and reduction of the neural tube. In the Thaliacea 
 there is a true alternation of generations (sexual and asexual generations 
 alternate). 
 
 Order 1. Larvacea (Perennichordata, Copelatse). Small free-swimming 
 larva-like Ascidians ; the swimming tail persists, as also the nerve-cord, 
 myotomes, and notochord (urochord). The anus and the two gill-slits 
 open directly to the exterior. A temporary gelatinous test secreted from 
 time to time by the epidermis. Appendicularia, Fritillaria. 
 
 Order 2. Ascidice (Tethyodea, Caducichordata in part), sea squirts. A 
 well-developed cartilaginous test and large pharynx perforated by 
 numerous secondary gill-slits. Mostly sedentary. 
 
 Ascidise simplices, oral and atrial apertures approximated: 
 Clavellina ; Ascidia mammillata ; Oiona intestinalis. Octacnemus 
 bythius, a deep-sea form. 
 
 Ascidise compositse, colonial forms with a common test ; indi- 
 viduals arranged in systems, each of which has a central cloacal cavity : 
 Botryllus. 
 
 Ascidise salpiformes; free swimming colonies in the form of a 
 hollow cylinder closed at one end ; the embryo develops into an asexual 
 cyathozooid, which produces four sexual ascidiozooids by budding ; 
 these constitute a new colony which continually enlarges by gemmation. 
 Pyrosoma, phosphorescent. 
 
 Order 3. Thaliacea (Caducichordata in part), salps. Pelagic transparent 
 ascidians. Oral and atrial apertures at opposite extremities. Develop- 
 ment with alternation of generations, sexual individuals united in a 
 chain. Salpa, wall of pharynx reduced to a dorsal band (gill), S. de- 
 mocratica with S. mucronata as the chain-form. The egg develops 
 to an embryo, which nourishes itself by a placenta in the brood-sac of 
 the parent, and is born as a solitary asexual salp (nurse). Doliolum 
 with pharynx perforated by two transverse rows of gill-clefts and com- 
 plicated alternation of generations. 
 
CHORDATA. 143 
 
 Subphylum C. Cephalochprda (Pharyngobranchii, 
 
 Acrania). 
 
 Marine Chordata with a continuous median fin but no paired fins. 
 Axial skeleton represented by the notochord which extends from one 
 end of the body to the other. No skull, jaws, true brain, sympathetic 
 system, auditory organ, heart or spleen. An unpaired eye as a pigment- 
 spot in the brain substance, and an unpaired olfactory pit. Blood 
 colourless. Body-cavity an enteroccele. Excretory organs as a pair of 
 short tubes opening into the atrial cavity surrounding the pharynx, this 
 cavity opens to the exterior by an atriopore. Gonads arranged rneta- 
 inerically ; no gonaducts. Only one known genus. Amphioxus lanceo- 
 latus, lancelet. 
 
146 CHORDATA. 
 
 Subphylum D. Vertebrata (Craniata). 
 Backboned Animals. 
 
 Chordata in which the notochord is supplemented, or more or less 
 replaced, by a mesodermic axial skeleton consisting of a skull and 
 segmented backbone. Never more than two pairs of limbs. Possess a 
 distinct head which lodges a brain that extends in front of the noto- 
 chord, two eyes with cup-shaped retina derived from the brain, two 
 auditory vesicles with semicircular canals, and two olfactory pits. There 
 is a heart with closed blood-system containing red as well as colourless 
 corpuscles, and a subordinated lymphatic (and lacteal) system com- 
 municating with a large eriteroccelic body-cavity. A spleen, and compact 
 excretory organs opening by longitudinal ducts to the exterior always 
 present. Gonads never arranged segmentally, ova usually pass into the 
 body-cavity and thence into oviducts, and sperm carried off by excretory 
 or special genital ducts. True hermaphrodites only found among fishes. 
 
CRANIATA 4 
 
 CHORD ATA. 147 
 
 ( 
 
 ' No jaws or limbs, . . . Cyclostomi. 
 
 
 
 Heart with aur- 
 
 Persistent or tem- 
 porary bran- 
 chial respira- 
 tion. Blood 
 same tempera- 
 
 
 icle and ven- 
 tricle. Med- 
 ian fin-rays. 
 Branchial re- 
 spiration. Pisces. 
 
 ture as sur- 
 rounding me- 
 dium. Without 
 amnion and al- 
 lantois. 
 
 Jaws present. 
 Two pairs of- 
 limbs. 
 
 Heart with two 
 auricles and a 
 ventricle. No 
 median fin- 
 
 Ichthyopsida 
 (Auamnia). 
 
 
 rays. Lungs; 
 temporary or 
 persistent 
 
 
 
 branchial res- 
 
 
 
 piration. A 
 
 
 i 
 
 . cloaca. Amphibia. 
 
 
 f Scales or scutes. 
 
 
 1 Ventricle (usu- 
 
 
 i ally) incom- 
 
 Branchial respira- 
 tion replaced by 
 allantoic respi- 
 ration in the 
 
 A single occipi- 
 tal condyle. 
 Mandible ar- 
 ticulates with 
 a quadrate " 
 bone. A clo- 
 
 pletely di- 
 vided. Blood 
 same tempera- 
 ture as sur- 
 rounding me- 
 dium. Reptilia. 
 
 embryo and 
 pulmonary re- - 
 
 aca. Ovipar- 
 ous. Sauzop- 
 
 Feathers. Ven- 
 tricle com- 
 
 spiration in the 
 adult. Possess 
 
 
 pletely di- 
 vided ; warm 
 
 an amnion. 
 
 
 blooded. Aves. 
 
 Amniota. 
 
 
 
 Two occipital condyles. Mandible 
 articulates with skull. A res- 
 
 
 piratory diaphragm. Ventricle 
 
 
 completely divided ; warm- 
 
 
 blooded. Female with mammary 
 
 
 glands. Viviparous, except the 
 Monotremata. Mammalia. 
 
148 CHORDATA. 
 
 Class I. Cyclostomi (Marsipobranchii). 
 
 Eel-like forms without paired fins, with a rounded suctorial mouth 
 not supported by jaws, an unconstricted notochord and cartilaginous 
 skeleton, and six to seven pairs of branchial pouches. Nostril unpaired. 
 
 Order 1. Hyperotreti. The nasal passage communicates with the mouth- 
 cavity. Myxine glutinosa, hag. 
 
 Order 2. Hyperoartia. Nasal passage ends blindly. Petromyzon. 
 Larval form Ammocastes. P. Planeri ; P. fluviatilis, lampern ; P. 
 marinus, lamprey. 
 
CHORD ATA. 153 
 
 Class II. Pisces. Fishes. 
 
 Cold-blooded forms, with paired fins and median fin-rays, branchial 
 respiration, and heart of one auricle and one ventricle. Mostly with 
 scales. 
 
 Order 1. Selachii (Elasmobranchii, Plagiostomi). Cartilaginous fishes 
 with placoid scales (dermal denticles), large pectoral and pelvic fins 
 (the former tribasal), five pairs of gill-pouches (usually), a muscular conus 
 arteriosus containing rows of valves, a spiral valve in the intestine, and 
 a cloaca. 
 
 Squalidse (Selachoidei), sharks, with lateral gill-clefts. Scyllium. 
 Cestracion. Mustelus laevis (smooth shark of Aristotle). Acanthias 
 vulgaris. Notidanus (Heptanchus), seven pairs of gill-pouches. To 
 these are appended the Rajidae (Batoidei), with ventral gill-clefts. 
 Pristis. Torpedo marmorata. Narcine. Raja clavata, R. batis. 
 
 Order 2. Holocephali. Closely allied to Selachii, but skin naked, upper 
 jaw fused to skull, notochord persistent, and four gill-clefts covered by a 
 membranous operculum. No cloaca. Chimsera, Callorhynchus. 
 
 Order 3. Ganoidei. Cartilaginous and bony fishes with scales or 
 scutes (ganoid scales), comb-shaped gills covered by a bony operculum, 
 muscular conus arteriosus containing rows of valves, and a spiral valve in 
 the intestine. No cloaca, but a urogenital aperture behind the anus. 
 Numerous fossil, few recent forms. 
 
 Cartilaginous Ganoids, with persistent unconstricted noto- 
 chord, heterocercal tail, spiracles and mandibular pseudobranchs. Aci- 
 penser, sturgeon, Scaphirhynchus, and Polyodon (Spatularia), recent. 
 Palaeoniscus Freieslebeni, Kupferschiefer. Platysomus. 
 
 Bony Ganoids, with notochord constricted by vertebral centra, 
 skull with membrane bones, and no mandibular pseudobranchs. Polyp- 
 terus bichir, double swim-bladder, and Oalamoichtliys, recent. Ho- 
 loptychius, Devonian. Amia, Cretaceous to recent, A. calva, recent. 
 Lepidosteus osseus, bony pike, recent. Pycnodus, the unconstricted 
 notochord surrounded by demi- vertebra, Jurassic to Tertiary. Lepidotus 
 and Amblypterus in the Kupferschiefer. 
 
 The armoured Ganoids Coccosteus, Pterichthys, and Cephalaspis 
 Lyellii are peculiar extinct forms from the Devonian. 
 
CHORDATA. 157 
 
 Order 4. Teleostei. Bony fishes with comb-like gills and (generally) 
 a hyoidean pseudobranch, with bony operculum and two valves in the 
 bulbus arteriosus. No optic chiasma, conus arteriosus, spiracles, or cloaca. 
 
 A. Physoklisti. Swim-bladder, when present, without pneu- 
 matic duct. 
 
 (a.) Lophobranchii. Exoskeleton of large dermal plates ; gills tufted. 
 Pegasus; Syngnathus acus, pipe-fish, and Hippocampus, sea-horse, 
 male with brood-pouch in which the eggs are hatched. 
 
 J>.) Plectognathi. Compact forms with immovably fused premaxillae 
 maxillae ; vertebral column short (18-20 vertebrae) ; a swim-bladder. 
 Ostracion, box-fish ; Orthagoriscus mola, sun-fish. Diodon. 
 
 (c.) Anacanthini, with soft fin-rays (Malacopteri) ; a swim-bladder. 
 Pleuronectidae, flat-fish. Gadus morrhua, cod, G. seglefinus, haddock, 
 G. merlangus, whiting. Fierasfer acus, parasitic in Holothuria. Ex- 
 ocoetus exiliens, flying-fish.. 
 
 (d.) Pharyngognathi, some of the fin-rays spinous ; hypopharyngeal 
 bones fused ; a swim-bladder. Labrus, Scarus. Embiotoca, viviparous. 
 
 (e.) Acanthopteri, with spinous fin-rays, and separate hypopharyngeal 
 bones ; mostly ctenoid scales. Perca fluviatilis, perch. Serranus 
 scriba, hermaphrodite. Gasterosteus aculeatus, stickleback ; the male 
 takes care of the young. Oottus. gobio, bull-head. Trigla, gurnard. 
 Gobius, gudgeon. Zoarces viviparus. Mugil. Anabas scandens, 
 climbing fish (Labyrinthici). 
 
 B. Physostomi. Soft fin-rays and separate hypopharyngeal bones. 
 Swim-bladder, when present, with a pneumatic duct. Anguilla vul- 
 garis, eel ; the male does not enter rivers. Mursena, Gymnotus elec- 
 tricus. Clupea harengus, herring. Mormyrus with pseudelectric 
 organ. Esox lucius, pike. Salmo salar, salmon,, with a fatty fin. Cy- 
 prinus carpio, carp. Cobitis fossilis, loach, Siiurus, Malapterurus 
 electricus, sheat-fish. 
 
CHORD AT A. 161 
 
 Order 5. Dipnoi, mud fishes ; lead on to the Amphibians. With per- 
 sistent notochord, paired limbs supported by a central jointed axis, 
 branchial and pulmonary respiration, muscular conus arteriosus, spiral 
 valve to the intestine, and a cloaca. 
 
 Monopneumona, with a single lung ; Trias to recent. Cera- 
 todus Forsteri, Queensland. 
 
 Dipneumona, paired lungs. Protopterus annectens, W. Africa 
 (with three pairs of branched external gills). Lepidosiren paradoxa, 
 Brazil. 
 
164 CHORD ATA. 
 
 Class III. Amphibia. 
 
 Cold-blooded Vertebrates with naked glandular skin, a sacral ver- 
 tebra, and (generally) paired limbs, consisting of girdle with free limb 
 transversely divided into three regions/ A cloaca, lungs, temporary 
 or permanent branchial respiration, and an incomplete double circula- 
 tion. Median fins, when present, not supported by tin-rays. Amnion 
 absent, and allantois represented by a urinary bladder. Frequently a 
 metamorphosis. 
 
 Order 1. Urodela (Caudata), tailed forms. 
 
 Ichthyoidea, notochord largely persistent, and vertebrae bicon- 
 cave : Proteus anguineus, in the underground streams of Carniolu ; 
 Siredon pisciformis, Axolotl, may lose its gills (becoming Ambly- 
 stoma); both preceding perennibranch. Menopoma, and Sieboldia 
 (Cryptobranchus) Japonicus, lose their gills (caducibranch), but retain 
 a pair of gill-clefts. 
 
 Salamandrina (Myctodera), adults without gills or gill-clefts; 
 vertebra} opisthoccelous. Triton cristatus, great water newt, with 
 spermatheca, oviparous. Salamandra maculosa, viviparous. 
 
 Order 2. Batrachia (Anura). With elongated hind-limbs, and 9-11 
 procoelous vertebrae. Tail, gills, and gill-slits only present in the larva. 
 Pipa dorsigera, female with brood- pouches on the back. Eana escu- 
 lenta, edible frog, R, temporaria, common frog, R. oxyrhinus. Bom- 
 binator igneus. Bufo vulgaris, toad. Hyla arborea, tree-frog, toes 
 with suckers. 
 
 Order 3. Apoda (Gymnophiona). Serpent-shaped subterranean forms 
 devoid of limbs, tail, gills, and gill-clefts. Skin with small dermal scales ; 
 vertebra* amphicrelous. Co3cilia lumbricoidea. Epicrium. Sipho- 
 nops. 
 
 Order 4. Steyocephali. Extinct forms, often of large size, with tail, 
 dermal armour, and well-ossified pubes. Carboniferous to Trias. 
 Labyrinthodon. 
 
168 CHOEDATA. 
 
 Class IV. Reptilia. 
 
 Cold-blooded Vertebrates breathing by lungs, and possessing scales or 
 scutes. A single occipital condyle, generally two sacral vertebrae, and 
 (in recent forms) ischial and pubic symphyses and separate pelvic bones 
 and nietatarsals. Heart with two auricles and either an imperfectly 
 divided ventricle or perfectly divided one with mixture of blood-streams 
 outside heart ; at least two aortic arches. 
 
 The following groups of Reptiles covered with scales or scutes are 
 grouped together as Lepidosauria (Plagiotremata) . 
 
 Order 1. Lacertilia (Sauria), lizards. Cloacal aperture a transverse 
 slit; a urinary bladder and two eversible copulatory organs. Protero- 
 saurus (Upper Dyas). Telerpeton (biconcave vertebrae, Trias). Gecko 
 and Platydactylus with biconcave vertebras. Iguana. Draco volans. 
 Chamseleo vulgaris. Scincus. Pseudopus Pallassii and Anguis 
 fragilis, blindworm, limbless. Lacerta agilis, L. vivipara. Monitor 
 varanus. Mosasaurus (Chalk). Amphisbsena. Hatteria (Spheno- 
 don), biconcave vertebrae, no copulatory organs. 
 
 Order 2. Pterosauria, Lias to Chalk. Antebrachium and fifth digit 
 of manus greatly elongated. Jaws usually dentigerous. Bones pneumatic. 
 Pterodactylus longirostris. Pteranodon, toothless. 
 
 Order 3. Ophidia, snakes. Limbless, and without urinary bladder. 
 Jaw apparatus with elastic bands. Typhlops, mouth cannot be widely 
 opened. 
 
 Colubriformia: Boa constrictor. Python- Coronella aus- 
 triaca ( = la^vis) smooth viper. Tropidonotus natrix, common snake. 
 Coluber. Dryophis. 
 
 Proteroglypha, poisonous snakes, with grooved fangs in the front 
 of the upper jaw : Naja tripudians, cobra. Hydrophis, Indian Ocean. 
 
 Solenoglyphia, with triangular head, and a poison-fang on either 
 side of the small upper jaw. Pelias (Vipera) berus, adder. Crotalus 
 horridus, rattlesnake. 
 
174 CHORDATA. 
 
 The following two groups are included under the name of Hydro- 
 s a u r i a (large aquatic forms with teeth firmly implanted in the jaw, 
 feet-modified for swimming and strong or armoured skin). 
 
 Order 4. Enaliosauria, with naked leathery skin, paddles, and 
 biconcave vertebrae (all from the Secondary period). Nothosaurus. 
 Plesiosaurus dolichodeirus. Ichthyosaurus communis. 
 
 Order 5. Crocodilia, with a long tail, webbed feet, scales, and scutes. 
 Teeth in sockets, ventricle completely divided, longitudinal cloacal 
 aperture and solid grooved penis. Teleosaurus, Jurassic, amphicoelous 
 vertebrae. Steneosaurus, Jurassic and Cretaceous, vertebras opisthocoe- 
 lous. Procoelous vertebrae from the Cretaceous on : Alligator lucius 
 and Caiman in America, Crocodilus vulgaris in the Nile. Gavialis 
 gaugeticus. 
 
 Order 6. Chelonia, with bony dorsal and ventral dermal shields ; 
 edentulous ; a urinary bladder and solid grooved penis. Chelone midas, 
 edible turtle. Trionyx. Cistudo (Emys) Europsea, Emys caspica. 
 Testudo Grseca, land tortoise. 
 
 Order 7. Dinosauria. Fossil forms which possessed more than two 
 sacral vertebras, and were in many respects, especially as regards the 
 pelvis and hind limb, intermediate between Eeptiles and Birds. Igu- 
 anodon. Megalosaurus Bucklandi (Jurassic and Wealden). Also 
 Dicynodon in the Trias. 
 
180 CHORD AT A. 
 
 Class V. Aves. Birds. 
 
 Feathered warm-blooded vertebrates with lungs closely adherent to 
 the back of the thorax and communicating with air-sacs which extend 
 between the viscera and into the bones. Ventricle completely divided, 
 the right auriculo-ventricular valve muscular, and a single aortic arch 
 curving to the right. Occipital region with a single condyle, numerous 
 vertebrae fused to form a pseud-sacrum, fore-limbs wings, pelvis with fused 
 bones, and (as a rule) neither pubic nor ischial symphyses, ankle-joint 
 between a tibio-tarsus and tarso-metatarsus. Eight ovary and oviduct 
 rudimentary ; oviparous. Some toothed fossil forms. 
 
 Order 1. Saururce. Numerous free caudal vertebrae ; jaws with teeth. 
 Archaeopteryx lithographica from the Upper Oolite. 
 
 Order 2. Ratitce (Cursores). Wings rudimentary, no keel to the 
 sternum. 
 
 Dinornis, extinct moa of New Zealand. Struthio camelus, ostrich, 
 Deserts of N., E., and S. Africa, Arabia, and Syria. Rhea Americana, 
 S. America. Dromseus, emeu, Australia. Casuarius, cassowary, New 
 Guinea, &c., and N. Australia. Apteryx australis, with complete dia- 
 phragm and air-sacs situated in the thorax; New Zealand. Odontolcae, 
 with teeth in grooves. Hesperornis, from the Cretaceous. 
 
CHORD AT A. 183 
 
 Order 3. Carinatce. Wings well developed, sternum with a keel. 
 
 Odontormae, biconcave vertebrae, teeth in sockets. Ichthyornis 
 from the Cretaceous. 
 
 Urinatores, wings short, sickle-shaped. Aptenodytes. Podi- 
 ceps. Alca impennis, exterminated. 
 
 Longipennes, beak hooked. Diomedea exulans, albatross. Pro- 
 cellaria Lams. 
 
 Steganopodes, with webbed feet. Pelecanus onocrotalus. 
 
 Lamellirostres, edges of the beak with horny plates. Cygnus 
 olor. Anser. Anas boschas. 
 
 G r a 1 1 ae, palate schizognathous. Scolopax. Grus cinerea. 
 
 Ciconiae, Ardea cinerea. Ciconia alba. Ibis mbra. Otis 
 tarda. 
 
 E a s o r e s, gallinaceous birds. Tetrao. Perdix. Gallus bankiva. 
 Pavo. 
 
 Columbae (Gyrantes), doves. Columba livia. Didus ineptus, 
 exterminated. 
 
 Raptores, birds of prey. Strix. Vultur. Falco. Aquila. 
 
 Passeres, special muscle to the syrinx. Fringilla coelebs. Alauda. 
 Hirundo. Sturnus. Corvus. Paradisea. 
 
 Macrochires. Caprimulgus. Cypselus apus. Trochilus co- 
 lubris. 
 
 P i c i, tongue slender and extensible. Picus. 
 
 Levirostres (Coccygomorphae) palate desmognathous. Cuculus 
 canorus. Buceros. Upupa epops. 
 
 P s i 1 1 a c i, upper jaw hinged on the skull. Psittacus erithacus. 
 Nestor. Strigops, no keel to sternum. 
 
188 CHORD AT A. 
 
 Class VI. Mammalia. 
 
 Hair-clothed, warm-blooded vertebrates, viviparous with the excep- 
 tion of Monotremes ; milk-glands always present in the female. A 
 double circulation, membranous right auriculo-ventricular valve, single 
 aortic arch curving to the left, and non-nucleated red blood-corpuscles. 
 A complete muscular diaphragm (respiratory muscle). Two occipital 
 condyles, and seven (6-9) cervical vertebrae. 
 
 Sub-Class I. PKOTOTHEKIA (Ornithodelphia). 
 
 Order 1. Monotremata. A persistent cloaca, epipubic (marsupial) 
 bones and beak-like horny jaws. Oviparous. Ova large and cleavage 
 meroblastic. No placenta. Only three genera are known. Ornitho- 
 rhynchus, duck-billed platypus, Australia and Tasmania ; Echidna 
 (Tachyglossus), and Proechidna (Acanthoglossus), spiny ant-eaters, the 
 former in Australia, Tasmania, and North New Guinea, the latter in 
 South New Guinea. 
 
4 
 
 CHORDATA. 191 
 
 Sub-Class II. METATHERIA (Didelphia, 
 Implacentalia). 
 
 Order 1. Marsupialia, pouched animals. Epipubic (marsupial) 
 bones ; in the female, two uteri, usually two vaginas and a marsupial 
 pouch, genital aperture and anus surrounded by a common sphincter ; 
 in the male, scrotum suspended in front of the penis. Auditory bulla 
 formed by alisphenoid, angle of the lower jaw inflected. Generally very 
 numerous teeth, which (with a few exceptions) are not changed ; incisors 
 
 O Q 
 
 never - -- . No allantoic placenta (so far as known). 
 3 3 
 
 (a.) R a p a c i a, carnivorous marsupials. Perameles, 4 -r- 
 
 3 13 
 
 Myrmecobius, . Dasyurus viverrinus, dasyure. Thyla- 
 
 o 1 4 5 
 
 cinus, native wolf. Thylacoleo, Pleistocene. 
 
 (6.) Pedimana, opossums. Dentition carnivorous, and resembling 
 
 . Didelphys Americana, Ameri- 
 can opossum ; as many as twenty-seven young at a birth. Chironectes. 
 (c.) Carpophaga, frugivorous marsupials with corresponding den- 
 tition. Phalangista vulpina, phalanger. Petaurus. Phascolarctos, 
 
 JL JL J_| 
 
 1 114* 
 (d.) Poephaga (Macropoda), springing marsupials. The two lower 
 
 incisors horizontal ; dentition LJ Microlestes from the 
 
 1014 
 
 Trias. Diprotodon australis in the Pleistocene. Macropus (Halma- 
 turus) gigantea, kangaroo. 
 
 (e.) Glirina (Rhizophaga), gnawing marsupials. Phascolomys 
 
 wombat 
 
 that of the Insectivora, ____ 
 
CHORDATA. 195 
 
 Sub-Class III. EUTHERIA (Monodelphia, 
 Placentalia). 
 
 The embryo is nourished by means of an allantoic placenta ; the niar- 
 supium and epipubic bones are absent ; vagina single ; scrotum, when 
 present, behind the penis. Alisphenoid does not form an auditory bulla ; 
 angle of mandible rarely inflected. 
 
 Fossil from the Eocene onwards. 
 
196 CHORD ATA. 
 
 A. NON-DECIDUATA. Placenta non-deciduate (except in some 
 Edentates). 
 
 Order 1. Edentata (Bruta). Teeth of persistent growth and without 
 enamel ; median incisors never present ; grinding teeth, when present, 
 similar and rootless. 
 
 (a.) Phytophaga, arboreal vegetable-feeding South American forms, 
 with dome-shaped deciduate placenta. Bradypus, three-toed sloth, with 
 tridactyle manus and nine cervical vertebrae. Choloepus, two-toed sloth, 
 with didactyle manus and six to seven cervical vertebrae. Megatherium 
 and Mylodon, gigantic ground sloths, from the South American Pleis- 
 tocene. 
 
 (6.) Entomophaga, insectivorous forms. Myrmecophaga, great ant- 
 eater (S. America), and Manis, pangolin or scaly ant-eater (E. Africa 
 and S. Asia), both toothless, the former with a dome-shaped deciduate, 
 the latter with a diffuse placenta. Orycteropus, aard-vark (S. Africa), 
 with zonary deciduate placenta. Dasypus and Chlamydophorus, arma- 
 dilloes (S. America) with bony dermal plates covered by epidermic scales, 
 and discoidal deciduate placenta. Glyptodon, a large armadillo from 
 the S. American Pleistocene. 
 
CHORDATA. 199 
 
 Order 2. Ungulata. Hoofed mammals, with elongated metaearpals 
 and metatarsals, and two successive sets of enamel-covered teeth. Cla- 
 vicles never present; never more than four digits. 
 
 (a.) Artiodactyla, paired digits, and grinding teeth with enamel folds. 
 Placenta diffuse or cotyledonary, 
 
 Non-ruminantia (Bunodontia). Anthracotherium, a primaeval 
 
 3 1 4 
 
 form from the Eocene. Porcus babymssa. Sus scrofa, pig, 3" y "4 
 
 Sus antiquus, Miocene. Hippopotamus amphibius. 
 
 Ruminantia (Bisulca, Pecora, Selenodontia), with complicated 
 stomach; median upper incisors always absent. Anoplotherium, 
 Miocene. Camelus. Auchenia, llama. Helladotherium and Siya- 
 therium, Miocene. Camelopardalis giraffus. Dorcatherium, Mio- 
 cene. Tragulus, chevrotain, recent Megaceros Hibernicus, Irish elk, 
 Pleistocene. Ceryus capreolus, roe, 0. elaphus, red deer, C. alces, 
 elk. Capra. Ovis. Bos primigenius, B. brachyceros, B. frontosus. 
 
 J>.) Perissodactyla, a large middle digit (3rd) symmetrical in itself, 
 pes with an odd number of toes. Placenta diffuse. Lophiodon, 
 Palseotherium, and Eohippus, in the Eocene. Tapirus, S. America 
 and S.E. Asia. Rhinoceros, S. Africa and S. Asia, 
 
CHORDATA, 203 
 
 Order 3. Cetacea. Marine (rarely fluviatile or estuarine) Mammals, 
 of fish-like form, with almost hairless skin, paddle-like fore-limbs with- 
 out nails, and horizontally flattened tail-fin. No hind-limbs, clavicles, 
 or distinct sacrum. Teeth, when present in adult, numerous, similar, 
 and without vertical successors. Placenta diffuse. 
 
 (a.) Denticeti, toothed Cetaceans ; Zeuglodon (Tertiary). Delphinus 
 delphis, dolphin. Phocsena communis, porpoise. Monodon, narwhal. 
 Physeter tursio. 
 
 (6) Mysticeti, right whales. Balsenoptera rostrata. Balsena Mys- 
 ticetus. 
 
 Order 4. Sirenia, sea-cows. Aquatic Mammals with scanty hair, 
 paddle-like fore-limbs with rudimentary nails, and horizontally flattened 
 tail-fin. No hind-limbs, clavicles, or sacrum. Dentition herbivorous. 
 Placenta diffuse. Manatus, manatee (E. coast of S. America and W. 
 coast of Africa), with six cervical vertebrae. Halicore, clugong (shores 
 of Indian Ocean and Red Sea). Rhytina Stelleri, exterminated last 
 century. Halitherium, Pliocene. 
 
CHORDATA. 207 
 
 B. DEGIDUATA. Placenta deciduate (except in the Prosimiae). 
 Order 5. Rodentia (Glires). Mammals with (usually) five clawed digits 
 to the maims and pes, chisel-shaped continuously growing incisors, 
 
 and 3-6 back teeth with transverse folds of enamel ; no canines. Pla- 
 centa discoidal. Lepus timidus, hare. L. cuniculus, rabbit. Cavia 
 cobaya, C. aperea, guinea-pig. Hydrochcerus capybara, Hystrix, 
 porcupine. Pedetes caffer, Cape jumping hare. Cricetus frumen- 
 tarius, hamster. Mus rattus, black rat. M. decumanus, brown rat. 
 M. musculus, mouse. Arvicola, vole. Myodes, lemming. Castor 
 fiber, beaver. Myoxus, dormouse. Sciurus vulgaris, squirrel. 
 
212 CHORD ATA, 
 
 Order 6. Proboscidea. Pentadactyle hoofed Mammalia with prehensile 
 proboscis, two tusk-like continuously growing upper incisors, no canines, 
 and composite grinding teeth. Placenta zonary. Mastodon, Miocene 
 to Pleistocene. Deinotherium, with two tusk-like lower incisors. Mio- 
 cene. Elephas primigenius, mammoth, Pleistocene, E. (Euelephas) 
 Indicus, Indian elephant, S. Asia, E. (Loxodon) Africanus, African 
 elephant, Africa S. of the Sahara. 
 
 Order 7. Hyracoidea (Lamnugia), conies. Small rodent-like Mammals 
 with pentadactyle (but two digits rudimentary) manus and tridac- 
 
 O f\ A. \ *%. 
 
 tyle pes. Dental formula , upper outer incisors soon fall out, 
 
 upper median incisors chisel-like, and continuously growing. Placenta 
 zonary. Hyrax, Africa and Syria. 
 
CHORD ATA. 215 
 
 Order 8. Tnsectivora. Small pentadactyle plantigrade or sub-planti- 
 grade Mammals, with clawed digits and (almost always) clavicles. 
 Always more than two lower incisors, canines small, molars with fangs 
 and sharply pointed crowns. Placenta discoidal Erinaceus Europaeus, 
 hedgehog. Sorex, shrew. Talpa, mole. 
 
 Order 9. Cheiroptera, bats. Mammals in which there is a flying mem- 
 brane (patagium) stretched between the body, limbs, and elongated digits 
 of the manus. Dentition complete, incisors smaller than the canines. 
 Clavicles well developed, sternum keeled, mammae pectoral. Placenta 
 discoidal. 
 
 (a.) Frugivora (Megacheiroptera), fruit-eating forms ; Pteropus edulis. 
 
 (6.) Insectivora (Microcheiroptera), insectivorous or blood-sucking 
 forms; Vespertilio. Plecotus. Vampyrus. 
 
218 CHORDATA. 
 
 Order 10. Carnivora (Ferae), beasts of prey. Pentadactyle clawed 
 
 o 
 
 Mammals, with complete dentition. Incisors generally , canines 
 
 3 
 
 strong. Clavicles absent or rudimentary. Placenta zonary. 
 
 (a) Fissipedia; terrestrial forms with well-developed claws, and ex- 
 
 o 
 
 tremities seldom webbed. Incisors , canines long and pointed, prse- 
 
 molars (denies spurii) pointed, molars mostly small and irregular ; the 
 last upper praemolars and first lower molars are large rending teeth (car- 
 
 nassial or sectorial). Ursus, p.m. _ m. . Mustela martes, martin, 
 p.m. L m. 1 . Viverra, p.m. 1 m. A . Canis, p.m. 1 m. JL . 
 Hyaena, p.m. m. . Felis, p.m. m. . 
 
 o 1 z 1 
 
 (b) Pinnipedia; aquatic forms with rudimentary claws and webbed 
 extremities; the hind-limbs united with the tail by a fold of skin. 
 Grinding teeth all similar, and never with more than two fangs. Phoca 
 
 01 R 
 
 vitulina, common seal, i. ^- c. p.m. + m. . Otaria, sea lion or 
 *z 1 o 
 
 eared seal. Trichechus rosmarus, walrus. 
 
222 CHORDATA. 
 
 Order 11. Prosimice (Lemuroidea), lemurs. Quadrupedal Mammals 
 with prehensile extremities, opposable hallux, and long non-prehensile 
 tail. Hallux (and generally pollex) with a flat nail, remaining digits 
 clawed. Orbits incompletely separated from the temporal fossae. Uterus 
 bicornuate, clitoris perforated by urethra, mammae pectoral and abdo- 
 minal, placenta diffuse. 
 
 (a.) Cheiromyini ; Cheiromys Madagascarensis, pollex non-oppo- 
 
 sable and clawed ; i. c. p.m. + in. . 
 10 3 
 
 (6.) Lemurini, with large opposable flat-nailed pollex ; lower incisors 
 forwardly directed. Limited to S. Africa and S. Asia ; Tarsius, 
 
 9-10 
 dentition 
 
 1 1 3 
 
 Lemur, 
 
 Order 12. Primates. Hallux (and generally pollex) with a flat nail 
 and relatively short. Orbits completely or almost completely separated 
 from temporal fossae. Uterus simple, clitoris not perforated by urethra, 
 a pair of pectoral mammae, placenta metadiscoidal. 
 
 (a.) Arctopitheci, marmozets (S. America); quadrupedal, long non- 
 prehensile tail, and non-opposable clawed pollex. Orbits not quite 
 
 O "I O O 
 
 walled off from temporal fossae. Dental formula '- . Hapale. 
 
 2132 
 
 (b.) Platyrrhini, New World monkeys; quadrupedal, long generally 
 prehensile tail, non-opposable pollex, nailed digits, and broad nasal 
 septum. Orbits completely separated from temporal fossae, coronal 
 suture V-shaped, alisphenoids united with parietals, external auditory 
 
 O 1 O 
 
 meatus not ossified. Dental formula 
 
 o 
 
 Neither cheek - 
 
 213 
 
 pouches nor ischial callosities. Cebus capuciniis. Mycetes niger, 
 howling monkey. Pithecia satanas. 
 
 (c) Catarrhini, Old World monkeys. Tail, when present, non- 
 prehensile, opposable pollex, nailed digits, and narrow nasal septum. 
 Orbits completely separated from temporal fossae, alisphenoids not 
 united with parietals, external auditory meatus ossified. Dental formula 
 
 - Cynomorpha, baboons, &c. ; quadrupedal tailed forms, 
 2123 
 
 with ischial callosities, and, as a rule, cheek-pouches. Cynocephalus. 
 Macacus. Cercopithecus sabseus. Anthropomorpha, arboreal 
 semi-erect tailless forms. Hylobates, gibbon (S. E. Asia and Malay 
 Archipelago), with ischial callosities. Pithecus (Satyrus), orang (Borneo 
 and Sumatra), 12 pairs of ribs. Gorilla engena (Troglodytes gorilla) 
 and Troglodytes niger, chimpanzee, both from W. Africa, and with 13 
 pairs of ribs. 
 
 (d) Anthropidae, distinguished from the other groups of Primates by 
 the following characters : Hair scanty, position habitually erect, hallux 
 non-opposable, cranio-facial angle not greater than 120, mandibular 
 symphysis with a mental prominence, no diastema in the dental series, 
 volume of brain not less than 55 cubic inches. Homo sapiens, man. 
 
PRINCIPLES OF DISTRIBUTION. 227 
 
 PRINCIPLES OF DISTRIBUTION. 
 
 Explanatory Theories 
 
 I. Theory of Special Creations, now abandoned. According to it: 1. Organisms 
 were created where now found. 2. The fauna and flora of any particular region must be 
 better adapted to it than any other fauna and flora. 3. Climate, soil, and position 
 explain all the phenomena of distribution. 
 
 II. Theory of Evolution, generally accepted. Regards modern distribution as the result 
 of innumerable changes that have affected (1) organisms ; (2) the surface of the globe. 
 
 1. Geological history shows that there has been a succession of faunas and floras passing 
 gradually into one another, old species becoming extinct, and new ones being evolved by 
 the combined influence of variation and heredity, which respectively originate and 
 accumulate new characters. Upon the whole a gradual advance in complexity has taken 
 place, but the geological record is extremely imperfect, especially as regards land organ- 
 isms. The process of change is still going on, and examples of modern extinction (e.g. 
 the New Zealand Dinornis and Sirenian form Rhytina) are well known, but the detec- 
 tion of newly evolved species involves greater difficulties. 
 
 Species once established have extended themselves over smaller or larger areas, 
 according to their powers of migration and surrounding conditions, i.e., their environ- 
 ment. Physical barriers, such as oceans, mountains, climate, and soil, have played an 
 important part in limiting such extension, but the competition of other forms has had a 
 still greater influence. Introduced forms often increase prodigiously, and even supersede 
 the indigenous ones, whence it follows that these last are not necessarily the best 
 adapted. Exs. Rabbits in Australia; the brown rat in England, which has almost 
 ousted the indigenous black rat. 
 
 2. Owing to the wearing away or erosion of the land by various agencies (chiefly the 
 different forms of water), and the action of subterranean forces by which upward and 
 downward movements of the earth's crust are produced, the distribution of land and sea 
 has constantly varied. Europe and North America, for example, have most likely been 
 connected at various times by laud occupying part of what is now the North Atlantic, and 
 Australia appears to have been once united with Asia. On the other hand, evidence is 
 found on every continental land surface of the former presence of the sea. In spite of 
 what has been said, the theory of "permanence of oceanic and continental areas" finds 
 much support. According to it the great oceans are of extreme antiquity, and, on the 
 lohole, more or less land has existed from very remote times within the present continental 
 areas. It is perhaps best to accept this theory only for the deeper parts of the great 
 oceans. An accurate knowledge of the contours of the ocean-floor is important in this 
 r.onnection, and serves as an important check upon speculations regarding former land- 
 unions. On this basis islands have been divided into oceanic and continental, which are 
 believed respectively to have been always isolated, and to have been connected with an 
 adjoining continent. 
 
 Oceanic Islands are : (a) generally remote from continents ; (6) separated from them 
 by very deep (usually over 1000 fathoms) water ; (c) of volcanic or coral nature ; (rf) 
 inhabited by forms which possess powers of migration capable of carrying them, actively or 
 passively, over more or less broad ocean tracts ; (e) characterised by numerous peculiar 
 species. Exs. The Azores, St. Helena, Ascension, coral islands of Pacific. 
 
 Continental islands are: (a) comparatively near a continent ; (b) separated from it by 
 comparatively shallow (under 1000 fathoms; water ; (c) of similar geological structure, 
 and not entirely volcanic or coral ; (d) inhabited by similar organisms, irrespective of 
 powers of migration. Such islands are : (1) Ancient continental, separated from the 
 nearest continent by fairly deep (over 100 fathoms) water, and presenting only a general 
 resemblance in the fauna and flora ; many peculiar species. Exs. Madagascar, Malay 
 Islands. (2) Recent continental, separated from the adjacent continent by shallow (not 
 more than 100 fathoms) water, and with closely similar fauna and flora ; very few peculiar 
 species. Exs. British Islands, Japan. Both (1) and (2) have presumably been united 
 with the adjoining continents, the latter at a recent date, geologically speaking. 
 
 The surface of the globe has also undergone numerous mutations as regards climate. 
 The temperate parts of N. America and Europe, for example, were at a geologically 
 recent period passing through a glacial epoch (the " great ice age"), as proved by ice- 
 worn and scratched rock-surfaces and rocks, boulder-clay. &c. On the other hand, fossil 
 plants evidencing subtropical conditions have been found in the Arctic regions. Many 
 
PRINCIPLES OF DISTRIBUTION. 229 
 
 theories have been advanced to account for secular changes of climate. The most satis- 
 factory is one by Wallace which attributes them to geographical revolutions (previously 
 suggested by Lyell), influenced by astronomical changes (variations in excentricity of 
 earth's orbit and movements of precession, as advanced by Croll). 
 
 All the preceding changes must have exerted a profound influence upon organisms, 
 and throw light upon many problems of distribution. 
 
 Areas of Distribution. May be mapped out for species genera, families, and orders. 
 In all cases : (1) Size and nature of boundaries very variable. (2) Need not be continuous. 
 
 (a.) Exs. of Limited Areas. The marmot only found in the Alps. A species of 
 humming-bird confined to the crater of the extinct volcano Chiriqui in Veragua. 
 
 Six genera of Lemurs are peculiar to Madagascar. The family Galeopithecidce (including 
 the single genus Galeopithecus) is limited to Malacca, Sumatra, Borneo, and the 
 Philippines. The order Monotremata only occurs in Australia, Tasmania, and New 
 Guinea. 
 
 (6.), Exs. of Extensive Areas. The leopard is distributed through the whole of Africa 
 and S. Asia to Borneo and E. China. The genus Felis (cat, lion, leopard, &c.) 
 ranges over most of the globe except Australia, the Pacific Islands, W. Indies, 
 Madagascar, and the more northerly parts of X. America and Asia. The family 
 Vespertilionidce, including 200 species of small insect-eating bats, occurs everywhere 
 within the tropical and temperate zones; while the family M uridce (rats, mice, &c.) is only 
 absent from Polynesia and New Zealand. 2. Discontinuity is generally a sign of antiquity, 
 the two or more parts being remains of a once continuous distributional area, in part of 
 which extinction has occurred. Changes in the distribution of land and sea have broken 
 up many once continuous areas. Examples. The variable hare (Lepus variabilis), 
 Europe and Asia N. of 55 ; Alps, Pyrenees, and Caucasus. The genus Tapirus, 
 S. America, S. E. Asia. Centetidce (a family of the Insectivora), Madagascar, Cuba, 
 Hayti. 
 
 Ganoid fishes are now represented by genera with the 'following distribution: 
 Acipenser, N. temperate and Arctic regions. Most species marine, others are found in 
 the Caspian Sea, Black Sea, and N. American lakes, with their rivers, also in the 
 Danube, Mississippi, and Columbia. Scapbirhynchus, Mississippi and tributaries. 
 Polyodon, Mississippi, and Yang-tse-Kiang. Polypterus, Nile and W. African rivers. 
 Calamoichtbys, rivers of Old Calabar. Amia, fresh-water, United States. Lepidos- 
 teus, fresh-water, N. America to Mexico and Cuba. Ganoid fishes are of great 
 geological antiquity, and were formerly a widely spread marine group. Most of the forms 
 now surviving have gradually accommodated themselves to a life in rivers, lakes, &c., where 
 the struggle for existence is less severe. 
 
 The peculiar distribution of the Dipnoi (p. 161) can be explained similarly. 
 
 The Marsupialia and Edentata (p. 235) are also good examples of interrupted areas of 
 distribution. 
 
 Zoological Regions, characterised by the presence of peculiar families and genera, 
 and by fne absence of other families and genera, have been formed for sea and land. The 
 most useful division of the latter is chiefly based on the Mammalia, but applies very well 
 to birds and reptiles and fairly to other groups. The regions thus established are six in 
 number. 
 
 I. Palcearctic Region. Temperate Europe and Asia and N. temperate Africa. Extends 
 W. to Iceland, the Azores, and Cape Verde Islands, and E. to Behring Straits and 
 Japan. Southern boundary somewhat indefinite, tropic of Cancer in Africa and Arabia, 
 river Indus, Himalayas, Nanling mountains. 
 
 II. Ethiopian Region. Africa and Arabia S. of the tropic of Cancer, and including 
 Madagascar. 
 
 III. Oriental Region. Asia, S. of Region I., and the western part of the E. Indies. 
 The E. boundary of this region (Wallace's line) passes between Bali, Borneo, and the 
 Philippines on the one hand, Lombok and Celebes on the other. The former islands are 
 therefore in the Oriental Region, the latter in the Australian Region. 
 
 IV. Australian Region. Australia, New Guinea, New Zealand, with the smaller 
 islands from Wallace's line to the Marquesas and Low Archipelago, and the tropic of 
 Cancer to the Macqnarie Islands. 
 
 V. Neotropical Region. S. America, the W. Indies, and tropical N. America, with the 
 exception of the central part of the Mexican table-land. 
 
 VI. Nearctic Region. Arctic and temperate N. America, with the central part of the 
 Mexican table-land. 
 
DISTRIBUTION OF MAMMALS. 231 
 
 DISTRIBUTION OF MAMMALS. 
 
 I. Palcearctic Region. Thirty-five families represented. Peculiar Genera. The camels, 
 six deer, the yak, six antelopes (including the chamois), and all wild sheep and goats, 
 
 except two species. Six p.g. of Muridce (rats and mice), two of mole-rats, and one 
 other ; dormice and pikas (calling hares) are almost confined to this region. Six p.g. of 
 moles ; the remaining two genera of which (Talpa, Urotrichus) extend, respectively, 
 
 into N. India and N. W. America. Five p.g. of Carnivora, including the racoon-dog, a 
 seal, and the badger ; the last just enters the Oriental region in China. 
 
 II. Ethiopian Region. Fifty families represented, of which nine are peculiar, i.e. 
 teropodidce. Hippopotamidce ; Camelopardidce. Potamogalidce (including Potamo- 
 
 m otter-like Insectiyore) ; Chrysochloridce (golden moles). Cryptoproctidee 
 (Cryptoprocta is a small civet-cat-like form peculiar to Madagascar) ; Protelidce 
 (Proteles, the aard-wolf, is allied to the hysenas and weasels) ; Cheiromyidce (contains 
 Cheiromy, the aye-aye, peculiar to Madagascar). 
 
 Peculiar Genera (besides those in the above families). Potamochaerus (river hog), 
 and Phacochaerus (wart hog); Hyomoschus (a small deer-like form), twelve p.g. 
 of antelopes. Thirteen p.g. of Muridce; Pedetes (a jerboa or jumping mouse); 
 An omalums (a flying squirrel); three other p.g. of Rodents. Three p.g. of elephant-shrews, 
 and the Insectivorous family Centetidce, except one genus from Cuba and Hayti. Three 
 p.g. of bats. Seventeen p.g. of Viverridce (civets and ichneumons), two p.g. of dogs, and 
 two p.g. of Mustelidce (weasels, otters, &c.). Nine p.g. of Lemurs. Eight p.g. of apes 
 and monkeys, the most important being Gorilla and Troglodytes (chimpanzee). 
 
 Peculiar Species. Among these are several species or Manis, the two-horned African 
 rhinoceroses, the zebras, African elephant, and lion. 
 
 Absent Palcearctic Forms. The genera Bos (wild ox), and Sus (wild boar), camels, 
 deer, goats and sheep, moles, bears. 
 
 III. Oriental Region. Forty-two families represented, of which two are peculiar, and 
 one other almost so, i.e., Galeopithecidce (including Galeopithecus, the flying lemur), 
 and Tupaiidce (tree-shrews), among Insectivora. Tarsiidas, a family of lemurs 
 (including only Tarsius spectrum, found in Sumatra, Bauca, and Borneo ; also outside 
 the Oriental region in Celebes.) 
 
 Peculiar Genera (besides those in the above families). Tragulus (chevrotain) ; 
 Cervulus (a deer) ; Bibos (wild cattle) ; three p,g. of antelopes. Platanista (a 
 dolphin found in Ganges and Indus). Three p.g. of Muridce; Pteromys (a flying 
 squirrel ; Acanthion (a porcupine). Gymnura (a hedgehog). Eleven p.g. of bats. 
 Twelve p.g. of Viverridce ; Cuon (a dog) ; five p.g. of Mustelidce; two p.g. of bears. 
 Loris and Nycticebus (lemurs). Four p.g. .of apes, including Pithecus (orang-utan), 
 and Hylobates (gibbon). 
 
 Peculiar Species. Among these are the Indian tapir, several species of rhinoceros, and 
 the Indian elephant. 
 
 IV. A ustralian Region. Twenty-eight families represented, of which eight are peculiar, 
 i.e. six out of the seven families of Marsupials, and the two families of Monotremes. 
 All of these, however, are absent from Polynesia and New Zealand. 
 
 Peculiar Genera (besides those in the above families). Babirusa (a hog) and Anoa (a 
 small kind of cow) in Celebes. Five p.g. of Muridce in Australia, and one of these in 
 Tasmania also. Three p.g. of bats. 
 
 Absent Forme. Australia and New Guinea possess no non-aquatic Mammals higher than 
 Marsupials, except some bats, mice, and rats. This points to extremely long-continued 
 isolation, which has afforded time for the Marsupials to become modified in the most 
 diverse directions, thus enabling them to fill places elsewhere occupied by other orders. 
 New Zealand is remarkable for the absence of all indigenous Mammals, so far as certainly 
 known, with the exception of two bats. 
 
 V. Neotropical Region. Thirty-seven families represented, of which seven are peculiar, 
 i.e. Bradypodidce (sloths), Dasypodidce (armadilloes), and Myrmecophagidce (true ant- 
 eaters). Chinchillidce (chinchillas) and Caviidce (cavies) among .Rodents. Cebidce (New*" 
 World monkeys) ; Hapalidce (marmozets). The Phyllostomidce (leaf-nosed bats) are 
 peculiar with th exception of a Calif ornian species. 
 
 Peculiar Genera (besides those in the above families). Chironectes and Hyracodon 
 (opossums). Dicotyles (peccary, also in Texas) ; Auchenia (llama) ; Elasmognattms 
 (a tapir). Inia (a dolphin, upper part of Amazon basin). Six p.g. of Muridce ; six p.g. of 
 Octodontidce (rat-like forms), two of them peculiar to W. Indies ; eight p.g. of Echimyidee 
 
DISTRIBUTION OF MAMMALS. 233 
 
 (spiny rats) ; two p.g. of Cercolabidce (tree porcupines) . Solenodpn (a hedgehog-like form 
 from Cuba and Hay ti). Twenty-six p.g. of bats, including the Vampires. Five p.g. of Canidce; 
 three p.g. of Mustelidce; Nasua (coati) and Cercoleptes (Kinkajou) ; Tremarctos 
 (spectacled bear) ; Otaria (an eared seal). 
 
 Peculiar Species. Among these are, twenty species of Didelphys (to which genus most 
 opossums belong). The American tapir. A species of racoon (genus Procyon)- 
 
 Absent Forms. Ungulata are scarce, deer and llamas being the only ruminants, tapirs 
 and peccaries the only non-ruminants. The only insectivores are Solenodon and a 
 species of shrew (Sorex). The Viverridce are absent. 
 
 VI. Nearctic Region. Thirty-two families are represented, of which one is peculiar, while 
 one other is almost so, i.e. Haploodontidce (rat-like forms allied to beavers and marmots), 
 and Saccomyidce (the pouched rats, of which one genus ranges into the N. of the Neo- 
 tropical region). 
 
 Peculiar Genera (besides those in the above families). Antilocapra (prong-horned 
 antelope), Aplocerus (a goat-like antelope), and Ovibos (the musk-sheep). Three p.g. of 
 Muridoe, Jaculus (a jerboa) , Cynomys (the so-called prairie dog), and Erethizon (the 
 tree porcupine), three p.g. of moles, two p.g. of bats, two p.g. of Mustelidce; Eumetopias 
 (an eared seal ; Halicyon (a seal). 
 
 Peculiar Species. Among these are two of Didelphys, a peccary, several deer, the 
 American bison, racoons, and the grizzly bear (Ursus ferox). 
 
 Absent Forms. Ungulates are ill represented, deer, the American bison, two antelopes, 
 a sheep, and the musk-sheep, being the only ruminants, while a peccary (Texas to Red 
 River), is the only non-ruminant. Hedgehogs, Viverridce, and monkeys are all unre- 
 presented. 
 
DISTRIBUTION OF ORDERS. 235 
 
 Distribution of Orders 
 
 1. Monotremata. Consists of only three genera, limited to part of the Australian 
 region. See p. 188. 
 
 No fossil forms are found elsewhere, so that the place of origin of this order is unknown. 
 
 2. Marsupialia. Consists of seven families (comprising thirty-six genera), of which only 
 one, the Opossum family (including three genera), occurs outside the Australian region. 
 The Opossums are Neotropical and Nearctic. 
 
 Fossil opossums occur in the Pleistocene of America, and in much older European 
 deposits (Eocene to Miocene). The Secondary rocks of Europe contain a number of 
 small forms, which probably resemble the ancestors of the Australian Marsupials. We 
 may therefore suppose that this order originated in the Palaearctic region, and then 
 extended into what is now Australia (at that time united by land with Asia), isolation 
 occurring soon after, followed by specialization in various directions. The Opossums 
 seem first to have existed in Europe, from whence they spread into America by former 
 northerly land-connections. 
 
 3. Edentata. This order is now chiefly limited to S. America, but Orycteropus is 
 peculiar to the Ethiopian region, while Manis is found both in that and the Oriental 
 region. 
 
 The geological evidence is in favour of considerable development in Africa, whence the 
 order would spread north to the Oriental and Palsearctic regions, and thence on to 
 America. The competition with higher forms has caused this extinction in most areas, 
 and Edentates appear to be most abundant in S. America, because the competition with 
 other animals is there comparatively small. The peculiar burrowing or climbing habits of 
 most of the genera also tend to preserve them, and these habits no doubt represent 
 attempts to escape from the severe competition with higher forms. The size of existing 
 Edentates is insignificant compared with that of Pleistocene S. American and European 
 genera. 
 
 4. Ungulata.(a) Artipdactyla. Non-rumniantia. Swine are only represented in 
 America by peccaries (Dicotyles) ; true swine are found in all the other regions but 
 only extend into the Australian as far as New Guinea. These animals are first known in 
 the European Eocene, and during Miocene and Pliocene times were as common in N. 
 America as Europe, but since then have almost entirely disappeared from the former 
 area. 
 
 The hippopotamus is now limited to the Ethiopian region, but fossil forms occur in 
 Europe (Pliocene and Pleistocene) and India (Miocene). 
 
 Ruminantia. Recent Camelidce are only found in the Neotropical and Palsearctic'regions, 
 but numerous forms occur in the Miocene and later deposits of N. America, where the 
 group originated. 
 
 Tragulidce or mouse-deer have also a discontinuous area of distribution W. Africa 
 (Hyomoschus) and Oriental region (Tragulus). This is accounted for by the presence of 
 Miocene forms in Europe, whence the family extended south. 
 
 Deer occur in all the regions except the Ethiopian, but do not extend far into the 
 Australian region. They appear to have taken origin in the Old World, from whence they 
 reached N. America in Miocene times, and afterwards passed to S. America. 
 
 Giraffes are at the present time confined to the Ethiopian region, but fossil forms are 
 known from S. Europe and India, and a northern temperate origin is probable. 
 
 Bovidce (oxen, sheep, antelopes, &c.) are present in all the regions except the Neotropical, 
 though they only just pass into the Australian, and are scarce in the Nearctic. The 
 family appears to have originated in the Palasarctic and Oriental regions during Miocene 
 times. 
 
 (&) Perissodactyla. Tapirs present a striking example of discontinuous distribution, 
 being found, on the one hand, in the Malay peninsula, Sumatra, and Borneo, and on the 
 other, in S. and Central America. True tapirs occur in the W. of Europe as far back 
 as Miocene times, but in America are not found further back than the Pleistocene. 
 Migration from the Palsearctic region is thus indicated. 
 
 Rhinoceroses are now only Ethiopian and Oriental, but they appear to have originated 
 in the Palsearctic region, where they extend back to the Miocene period. In Pliocene 
 times they also ranged into N. America. 
 
 The genus Equus (horse, ass, zebra) is now limited to the Ethiopian and Palsearctic 
 regions. It appears to have originated in the latter area during Miocene times, and then 
 migrated not only into the Ethiopian, but also into the Oriental, Nearctic, and Neotropical 
 regions, as proved by fossil forms. 
 
 5. Sirenia.See p. 203. 
 
DISTRIBUTION OF ORDERS. 237 
 
 6. Rodentia. Very widely distributed ; occurring in all the regions, but in Madagascar 
 and Australia only represented by Muridce. They attain their largest development in 
 S. America. 
 
 The order is of great geological antiquity, for some living genera extend back to the 
 Eocene. Rodents probably originated in the Palsearctic region, whence migrations 
 took place at an early date to S. America and S. Africa, allowing time for great 
 specialization. 
 
 7. Proboscidea. Elephants are now limited to the Ethiopian and Oriental regions, but 
 formerly had a much wider extension. 
 
 Palaearctic forms occur from Miocene to Pleistocene times, and elephants have lived in 
 India since the Miocene period. Numerous fossil examples occur in the Pliocene and 
 Pleistocene deposits of N. and S. America. 
 
 8. Hyracoidea. Almost entirely limited to the Ethiopian region, but range northwards 
 as far as Syria. 
 
 9. Insectivora. Very widely distributed, and represented by numerous specialized 
 forms. Absent from S. America and Australia. 
 
 This order is a very ancient one, as shown by the fact that Miocene forms mostly belong 
 to existing families. Extinction appears to be slowly taking place, and has led to many 
 cases of discontinuous distribution, e.g., the Centetidce, represented by Solenodon in the 
 W. Indies, and Centetes, with four other genera, in Madagascar. 
 
 10. Cheiroptera. Bats, as might be expected, are found in all the great areas, but the 
 Frugivora are absent from the Nearctic and Neotropical regions, as are the Horse-shoe 
 bats (Rhinolophidce) among insectivorous forms. On the other hand, the Leaf-nosed bats 
 (Phyllostomidce) are almost exclusively Neotropical. 
 
 Fossil bats, very like recent species, date from Eocene times, and the order is un- 
 doubtedly one of extreme antiquity. 
 
 11. Carnivora.(a) Fissipedia. Occur in all the regions, except, perhaps, the 
 Australian (the "native dog "of Australia is only doubtfully indigenous), but are 
 especially characteristic of the Ethiopian and Oriental, which possess almost all the 
 Viverridce and Hycenidce, with a great many of the Felidce and Mustelidce. Two genera, 
 Cryptoprocta and Proteles, constituting distinct families, are limited respectively to 
 Ma'dagascar and S. Africa. Bears, however, are absent from the Ethiopian region, 
 and are only represented by one species in the Neotropical region, which is also very poor 
 in other Carnivora. The Procyonidce are small bear-like forms, found in the Nearctic 
 and Neotropical regions, and include the racoons (Procyon), coatis (Nasua), and 
 kinkajous (Cercoleptes). 
 
 Fossil Carnivores date back to the Lower Eocene, but the recent families were not then dif- 
 ferentiated. The order appeai-s to have originated in the northern half of the Old World. 
 
 (6) Pinnipedia. Seals are limited to cold and temperate seas, and are also found in the 
 Caspian, Sea of Aral, and Lake Baikal, all of which, at no very distant epoch, were con- 
 nected with the Arctic Ocean. 
 
 Walruses characterise the North Polar regions. 
 
 12. Prosimice. (a) Cheiromyini. Only one form, the aye-aye (Cheiromys) which is 
 restricted to Madagascar. 
 
 (b) Lemurini. Practically limited to the Ethiopian and Oriental regions. Indris, 
 Lemur, and four other genera are only found in Madagascar. Tarsius constitutes a 
 distinct family, and is limited to Sumatra, Banca, Borneo, and Celebes. 
 
 Lemurs date back to the Eocene in Europe. 
 
 13. Primates. (a) Arctopitheci and (6) Platyrrhini are confined to the Neotropical 
 region. 
 
 (c) Catarrhini are found only in the Old World. 
 
 Cynomorpha are especially Ethiopian and Oriental, but also extend into the Pate- 
 arctic region, and into the Australian region as far as Timor. 
 
 Anthropomorpha present a marked example of discontinuous distribution. See 
 p. 222. 
 
 The order dates back to the Eocene. 
 
 Origin and Migrations of the Mammalia. The Class, and most likely all the 
 Orders, originated in the Northern Hemisphere. Australia was isolated at a very early 
 date, and therefore has preserved a very ancient Mammalian fauna. S. America and S. 
 Africa were severed somewhat later, to be afterwards re-united, and they also have 
 preserved some very ancient forms. The northerly connection between the Eastern 
 and Western Hemispheres was then broken, not only by submergence of land, but also 
 by a lowering of temperature. The Oriental and Ethiopian regions were also marked off 
 by the formation of the Himalayas and the desert zone stretching from the Sahara to 
 Central Asia. 
 
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