THE LIBRARY OF THE UNIVERSITY OF CALIFORNIA PRESENTED BY PROF. CHARLES A. KOFOID AND MRS. PRUDENCE W. KOFOID A MANUAL OF ZOOLOGY A MANUAL OF ZOOLOGY FOR THE USE OF STUDENTS. fntwtarto 0n % f onripte 0f BY HENRY ALLEYNE NICHOLSON, M.D., D.Sc., M.A., PH.D. (GOTT.), F.R.S.E., F.G.S. LECTURER ON NATURAL HISTORY IN THE MEDICAL SCHOOL OF EDINBURGH : VICE-PRESIDENT OF THE GEOLOGICAL SOCIETY OF EDINBURGH, KTC. AUTHOR OF 'ADVANCED TEXT -BOOK OF ZOOLOGY FOR THE USE OF SCHOOLS: 'ESSAY ON THE GEOLOGY OF CUMBERLAND AND WESTMORELAND;' 4 GRAPTOLITES OF THE SKIDDAW SERIES,' ETC. ETC. VOL. II. — VERTEBRATE ANIMALS. WILLIAM ELACKWOOD AND SONS, I'DINBURGH AND LONDON. MDCCCLXX. V, CONTENTS. PAKT II.-VERTEBRATE ANIMALS. CHAPTER LIII. PAGE General characters of the Vertebrata — Osseous system — Digestive sys- tem — Blood — Circulation — Respiration — Nervous system — Organs of sense — Reproduction — Divisions, . . . 323-339 CHAPTER LIV. General characters of Fishes — Integumentary system — Osseous system — Fins — Respiration — Circulation — Digestive system — Swim- bladder — Nervous system — Olfactory organs — Reproduction, 340-352 CHAPTER LV. Pharyngobranchii — Marsipobranchii, ...... 353-357 CHAPTER LVI. Teleostei — Sub-orders — Malacopteri — Anacanthini — Acanthopteri^- Plectognathi — Lophobranchii, ...... 357-364 CHAPTER LVII. Ganoidei — Sub-orders — Lepidoganoidei — Placoganoidei, . . 364-369 CHAPTER LVIII. Elasmobranchii and Dipnoi — Sub-orders of Elasmobranchii — Holo- cephali — Plagiostomi — Dipnoi, ...... 370-377 CHAPTER LIX. Distribution of Fishes in time, . . . . ... . 377-380 CHAPTER LX. General characters of the Amphibia, . . . . . . 381-383 (VJ350114 IV CONTENTS. CHAPTER LXI. Orders of Amphibia — Ophiomorpha — Urodela — Anoura — Develop- ment of Frog — Families of Anoura — Labyrinthodontia — Distribu- tion of Amphibia in time, ....... 384-392 CHAPTER LXII. General characters of Reptilia — Endoskeleton— Exoskeleton— Diges- tive system — Circulatory system — Respiratory system, . . 393-397 CHAPTER LXIII. Divisions of Reptilia — Chelonia — General characters of Chelonian Reptiles — Distribution of Chelonia in time — Ophidia — General characters of Snakes — Sub-orders — Distribution of Ophidia in time, . 397-407 CHAPTER LXIV. Lacertilia — Families of Lacertilia — Distribution of Lacertilia in time — Crocodilia — Sub-orders of Crocodilia — - Distribution of Croco- dilia in time, 408-415 CHAPTER LXV. Extinct orders of Reptiles— Ichthyopterygia — Sauropterygia — Ano- modontia — Pterosauria — Dinosauria, 416-422 CHAPTER LXVI. General characters of the class Aves — Feathers — Vertebral column — Skull — Pectoral arch and fore-limb — Pelvic arch and hind-limb — Digestive system — Respiratory system — Circulatory system — • Reproductive organs — Nervous system and organs of Sense, . 423-441 CHAPTER LXVI I. General divisions of the class Aves — Characters and families of the order Natatores — Characters and families of Grallatores, . 441-450 CHAPTER LXVI I L Characters of Cursores — Characters and sections of Rasores — Galli- nacei — Columbacei, ........ 451-456 CHAPTER LXIX. Characters and families of Scansores — Characters of Insessores — Coni- rostres — Dentirostres — Tenuirostres— Fissirostres, . . 457-463 CHAPTER LXX. Characters and sections of Raptores — Characters of Saururae, . 464-467 CHAPTER LXXI. Distribution of Aves in time, ....... 467-470 CONTENTS. CHAPTER LXXII. General characters of the Mammalia — Skeleton — Pectoral arch and fore-limb — Pelvic arch and hind-limb — Teeth — Dental formula — Digestive system — Circulatory system — Respiratory system — Re- productive system — Mammary glands — Nervous system — Integu- mentary appendages, ........ 471-483 CHAPTER LXXITI. Classifications of the Mammalia — Synopsis of the Mammalian orders, 484-488 CHAPTER LXXIV. Characters of Monotremata — Characters and divisions of Marsu- pialia, 4§9-497 CHAPTER LXXV. Characters and families of Edentata, 498-502 CHAPTER LXXVI. Characters of Sirenia — Characters and families of Cetacea, . . 502-5 1 1 CHAPTER LXXVII. General characters of Ungulata — Perissodactyla — Artiodactyla — Ru- minantia — Structure of the stomach in Ruminants — Dentition of Ruminants — Sections of Ruminants, 511-526 CHAPTER LXXVI 1 1. Characters of Hyracoidea — Characters of Proboscidea, . . 526-530 CHAPTER LXXIX. Characters of Carnivora — Pinnigrada — Plantigrada— Digitigrada, 530-541 CHAPTER LXXX. Characters of Rodentia — Families of Rodentia, . • . . . 541-546 CHAPTER LXXXI. Characters of Cheiroptera — Sections of Cheiroptera, . . . 546-549 CHAPTER LXXXI I. Characters of Insectivora — Families of Insectivora — Galeopithe- cidas, 549-551 CHAPTER LXXXIII. Characters of Quadrumana — Sections of Quadrumana — Strepsirhina — Platyrhina — Catarhina, . . . . . . 552-558 vi CONTENTS. CHAPTER LXXXIV. Characters of Bimana, 558-559 CHAPTER LXXXV. Distribution of Mammalia in time — Geographical succession of or- ganic forms — Tabular view of the chief sub-divisions of the Ver- tebrata, 559'57i GLOSSARY, 572-602 INDEX, 603-622 LIST OF ILLUSTRATIONS. 116. 117. 118. 119. 120. 121. 122. I23. I24. 125. 126. 127. 128. I29. 130. 132. 133- 134- 136. 137- 138- 139- I4O. 141. I42. H3- 144- PAGE Transverse Sections of the body of an invertebrate and a vertebrate animal, 324 Embryology ofVertebrata, 325 Lumbar Vertebra of Whale, and diagram of thoracic vertebra, .... 328 Skeleton of the Beaver, 329 Pectoral Limb of Chim- panzee, 331 Pelvic Limb of Chimpan- zee, 332 Diagram of the digestive system of a Mammal, . 333 Blood-corpuscles of Ver- tebrate^ . . . . .334 Diagram of the Circula- tion of a Mammal, . -335 Scales of Fishes, . . . 340 Skeleton of the Common Perch 341 Skull of the Cod, . . .343 Os hyoides and branchial arches of the Perch, . 345 Pectoral Limbs of Fishes, 346 Outline of Percagranu- lata, 348 Homocercal and hetero- cercal Tails, .... 349 Diagram of the Circula- tion of a Fish, . . .350 Diagram of the Lancelet, 354 Lamprey, 355 Heart of Teleostean and Ganoid Fishes, . . . 359 Gymnotus electricus, . . 360 Rhombus punctatus, . . 362 Ostracion cornutus, . . 364 Polypterus and Osteolepis, 367 Cephalaspis Lyellii, . .369 Coccosteus and Pterichthys, 369 Head of Piked Dog-fish, 371 Carcharias and Chimcera, 372 Raia marginata, . . .374 Lepidosiren annectens, . 376 FIG. PAGE 145. Spines and Teeth of Pa- laeozoic Elasmobranchii, 379 146. Hyla leucotania, . . . 382 147. Proteus anguinus, . . 385 148. Axolotl, 386 149. Triton cristatus, . . . 387 150. Skeleton of the Frog, . 388 151. Development of the Frog, 389 152. Footprints of a Labyrin- thodont, 391 153. Skull of a Serpent, . . 395 1 54. Diagram of the circulation in Reptiles, .... 396 155. Skeleton of Tortoise, . 399 156. Hawk's-bill Turtle, . . 400 157. Eye of Serpent and Head of Viper, 403 158. Head of Ringed Snake, of Viper, and of Blind - worm, 407 159. Iguana, 408 160. Blind-worm, .... 410 161. Head of Chameleon, . 412 162. Skull of Crocodilus bi- porcatus, 414 163. Ichthyo saurus communis, 417 164. Plesiosaurus dolichodeirus, 418 165. Pterodactylus brevirostris, 419 1 66. Quill-feather, .... 425 167. Skull of Spur - winged Goose, 428 1 68. Pectoral Arch and Fore- limb of Penguin, . . 429 169. Fore-limb of Jer- falcon, . 430 170. Hind-limb of Loon, . . 432 171. Digestive System of the Common Fowl, . . . 434 1 72. Lung of Goose, . . . 436 173. Foot of Cormorant and Beak of Goose, . . . 444 174. Leg of Curlew, Head of Snipe, and Beak of Avocet, 448 175. Foot of Ostrich, and Breast-bone of Emeu, . 45 1 Vlll LIST OF ILLUSTRATIONS. 176. Foot of Fowl, and Head of Guinea-fowl, . . . 454 177. Foot of Woodpecker, and Head of Love-bird, . .458 1 78. Feet and Heads of Inses- sores, 459 179. Head of Bullfinch, . . 461 1 80. Foot of Peregrine Falcon, and Head of Buzzard, . 464 181. Foot of Tawny Owl, and Head of White Owl, . 465 182. Head of Vulture, . . . 466 183. Arch&opteryx macrura^ . 467 184. Fore-limbs of Horse and Deer, 476 185. Teeth of Chimpanzee, . 480 1 86. Ornithorhynchus para- doxus, 490 187. Pelvis of Kangaroo, . . 492 1 88. Dentition of Thylacinus and Hypsiprymnus, . 494 189. Myrmecobius fasciatus, . 497 190. Hand of three- toed Sloth, 499 191. Chlamyphorustruncatiis, 5°° 192. Dugong, 503 193. Skull of Right Whale, . 505 194. Diagram of Baleen-plates of a Whale, .... 507 1 95. Physeter macrocephalus, . 509 196. Delphinus delphis, . .510 197. Feet of Ungulatat . . .512 198. Head of Two - horned Rhinoceros, . . . .514 199. Stomach of a Sheep, . . 519 200. Skull of hornless Sheep, 520 201. Skull of the Indian Ele- phant, 528 202. Skull of Deinotherium, . 530 203. Feet of Carnivora, . -531 204. Phoca grcenlandica, . . 532 205. Skull of the Walrus, . 533 206. Skull of Jackal, . '.. . 539 207. Skull of Lion, .... 540 208. Skull of Beaver, . . . 542 209. Skeleton of Fox-bat, . . 547 210. Head of Vampire-bat and Fox-bat, 548 211. Skull of Hedgehog, . . 550 212. Skulls of Orang and Eu- ropean adult, . . . .557 213. Jaw of Dromatherium, . 561 214. Jaws of Phascolotherium, Triconodon, Amphithe- riiim, and Plagtaulax, . 561 215. Skull of Diprotodon, . .563 216. Skeleton of Megatherium, 563 217. Glyptodon clavipes, . .564 2 1 8. Skeleton of Megaceros Hi- bernicus, 566 219. Skeleton of Mastodon, . 567 220. Skeleton of Mammoth, . 567 PART II. VERTEBRATE ANIMALS VERTEBRATE ANIMALS. CHAPTER LIII. GENERAL CHARACTERS AND DIVISIONS OF THE VERTEBRATA. THE five sub-kingdoms which we have previously considered — viz., the Protozoa, Coilenterata, Annuloida, Annulosa, and Mol- lusca — were grouped together by the French naturalist Lamarck to form one great division, which he termed Invertebrata, the remaining members of the animal kingdom constituting the division Vertebrata. The division Vertebrata, though includ- ing only a single sub-kingdom, is so compact and well-marked a division, and its distinctive characters are so numerous and so important, that this mode of looking at the animal kingdom is, at any rate, a very convenient one. The sub-kingdom Vertebrata may be shortly defined as com- prising animals in which the body is composed of a number of definite segments, arranged along a longitudinal axis ; the nervous system is in its main masses dorsal, and the neural and hcemal regions of the body are always completely shut off from one an- other by a partition ; the limbs are never more than four in number, and are always turned away from the neural aspect of the body ; mostly there is the bony axis known as the " spine" or " vertebral column" and in all the structure known as the " note- chord" is present — in the embryo, at any rate. These charac- ters distinguish the Vertebrata, as a whole, from the Invtrte- brata; but it is necessary to define these broad differences more minutely, and to consider others which are of little less importance. One of the most obvious, as it is one of the most funda- mental, of the distinctive characters of Vertebrates is to be found in the shutting off of the main masses of the nervous 324 MANUAL OF ZOOLOGY. system from the general cavity of the body. In all Inverte- brate animals, without exception, the body (fig. 115, A) may be regarded as a single tube, enclosing all the viscera ; and consequently, in this case, the nervous system is contained within the general cavity of the body, and is not in any way shut off from the alimentary canal. The transverse section, Fig. 115. — A, Tranverse section of the body of one of the higher Invertebrata : a Body-wall ; b Alimentary canal ; c Haemal system ; n Nervous system. B, Trans- verse section of the body of a Vertebrate animal : a Body-wall ; b Alimentary canal ; c Haemal system ; n Sympathetic system of nerves ; »' Cerebro-spinal system of nerves ; ch Notochord. however, of a Vertebrate animal exhibits two tubes (fig. 115, B) one of which contains the great masses of the nervous system — that is, the " cerebro-spinal axis," or brain and spinal cord — whilst the other contains the alimentary canal and the chief circulatory organs, together with certain portions of the ner- vous system, known as the " ganglionic" or "sympathetic" system. Leaving the cerebro-spinal centres out of sight for a moment, we see that the larger or visceral tube of a Vertebrate animal contains the digestive canal, the haemal system, and a gangliated nervous system. Now this is exactly what is con- tained in the visceral cavity of any of the higher Invertebrate animals ; and it follows from this, as pointed out by Von Baer, that it is the sympathetic nervous system of Vertebrates which is truly comparable to, and homologous with, the nervous sys- tem of Invertebrates. The cerebro-spinal nervous centres of the Vertebrata are to be regarded as something superadded, and not represented at all amongst the Invertebrata. The tube containing the cerebro-spinal centres is formed as follows : — At an early period in the development of the em- bryo of any Vertebrate animal, the portion of the ovum in which development is going on — the "germinal area" — be- comes elevated into two parallel ridges, one on each side of the middle line, enclosing between them a long groove, which is known as the " primitive groove" (fig. 1 16, A, B). The ridges which bound the primitive groove are known as the " laminae GENERAL CHARACTERS OF THE VERTEBRATA. 325 dorsales ;" and they become more and more raised up, till they ultimately meet in the middle line, and unite to form a tube, within which the cerebro-spinal nervous centres are developed. It follows from its mode of formation that the inner wall of the tube formed by the primitive groove, which remains as the septum between the cerebro-spinal canal and the body-cavity, is nothing more than a portion of the primitive wall of the body of the embryo. And there appears to be little doubt, as be- lieved by Remak and Huxley, that the cerebro-spinal nervous centres are " the result of a modification of that serous layer of the germ, which is continuous elsewhere with the epidermis" (Huxley). Fig. 116. — Embryology of Vertebrata. A, Portion of the germinal area of the ovum of a Bitch, showing the primitive groove (after Bischoff). B, Profile view of the same. C, Diagram representing the amnion and allantois : e Embryo ; a Am- nion ; u Umbilical vesicle ; b Allantois ; f Pedicle of the allantois, afterwards the urinary bladder. D, Head of an embryo, showing the visceral arches (z/ v). Another remarkable peculiarity as regards the nervous sys- tem is found in the fact that in no Vertebrate animal does the alimentary canal pierce the main masses of the nervous system, but turns away to open on the opposite side of the body. In most Invertebrates, on the other hand, in which there is a well-developed nervous system, this is perforated by the gullet, so that an cesophageal nerve-collar is formed, and some of the nervous centres become prae-cesophageal, whilst others are post-cesophageal. Furthermore, the floor of the "primitive groove" in the embryo of all Vertebrates has developed in it at an early period the structure known as the " notochord " or " chorda dorsalis" (fig. 115, B, ch). This structure, doubtfully present in any Invertebrate, is a semi-gelatinous or cartilaginous col- 326 MANUAL OF ZOOLOGY. lection of cells, forming a rod-like axis, which tapers at both ends, and extends along the floor of the cerebro-spinal canal, supporting the cerebro-spinal nervous centres. In some Ver- tebrates, such as the Lancelet (Amphioxus\ the notochord is persistent throughout life. In the majority of cases, however, the notochord is replaced before maturity by the structure known as the "vertebral column" or "backbone," from which the sub-kingdom Vertebrata originally derived its name. This is not the place for an anatomical description of the spinal column, and it is sufficient to state here that it is essen- tially composed of a series of cartilaginous, or more or less completely ossified, segments or vertebra, arranged so as to form a longitudinal axis, which protects the great masses of the nervous system. It is to be remembered, however, that all Vertebrate animals do not possess a vertebral column. They all possess a notochord; but this may be persistent, and in many cases the development of the spinal column is extremely imperfect. Another embryonic structure which is characteristic of all Vertebrates, is found in the so-called " visceral arches " and " clefts" (fig. 1 1 6, D). The "visceral arches" are a,series of par- allel ridges running transversely to the axis of the body, situ- ated at the sides of, and posterior to, the mouth. As develop- ment proceeds, the intervals between these ridges become grooved by depressions which gradually deepen, until they become converted into a series of openings or " clefts," where- by a free communication is established between the upper part of the alimentary canal (pharynx) and the external medium. The limbs of Vertebrate animals are always articulated to the body, and they are always turned away from the neural aspect of the body. They may be altogether wanting, or they may be partially undeveloped ; but there are never more than two pairs, and they always have an internal skeleton for the attachment of the muscles of the limb. A specialised blood-vascular or " haemal " system is present in all the Vertebrata, and in all except one — the Amphioxus — there is a contractile cavity or heart, which never consists of less than two chambers provided with valvular apertures. In all the Vertebrata the heart is essentially a respiratory heart — that is to say, it is concerned with driving the impure or venous blood to the breathing-organs ; and in its simplest form (fishes) it is nothing more than this. In the higher Vertebrates, how- ever, there is superadded to this a pair of cavities which are concerned in driving the pure or arterial blood to the body. In the case of the Mammals, these two circulations are often GENERAL CHARACTERS OF THE VERTEBRATA. 327 spoken of as the "lesser" or "pulmonary" circulation, and the " greater " or " systemic " circulation. In all Vertebrates there is that peculiar modification of the venous system which is known as the " hepatic portal system." That is to say, a portion of the blood which is sent to the ali- mentary canal, instead of returning to the heart by the ordi- nary veins, is carried to the liver by a special vessel — the vena portcz — which ramifies through this organ after the manner of an artery. In all Vertebrates, also, is found the peculiar system of vessels known as the "lacteal system." This is to be regarded as an appendage of the venous system of blood-vessels, and consists of a series of vessels which take up the products of digestion from the alimentary canal, elaborate them, and finally empty their contents into the veins. Lastly, the masticatory organs of Vertebrates are modified portions of the walls of the head, and never " hard productions of the alimentary mucous membrane or modified limbs " (Huxley), as they are amongst the Invertebrata. The above are the leading characters of the Vertebrata as a whole ; but before going on to consider the primary divisions of the sub-kingdom, it may be as well to give a veiy brief and general description of the anatomy of the higher and more typical Vertebrates, commencing with their bony framework or skeleton. The skeleton of the Vertebrata may be regarded as consisting essentially of the bones which go to form the head and trunk on the one hand (sometimes called the "axial" skeleton), and of those which form the supports for the limbs (" appendicular" skeleton) on the other hand. The bones of the head and trunk may be looked upon as essentially composed of a series of bony rings or segments, arranged longitudinally, one behind the other. Anteriorly these segments are much expanded, and likewise much modified, to form the bony case which encloses the brain, and which is termed the cranium or skull. Behind the head the segments enclose a much smaller cavity, which is called the " neural " or spinal canal, as it encloses the spinal cord ; and they are arranged one behind the other, forming the vertebral column. The segments which form the vertebral column are called "vertebrae," and they have the following general structure: — Each vertebra (fig. 117, A) consists of a central piece, which is the fundamental and essential element of the vertebra, and is known as the "body" or "centrum" (c). From the upper or posterior surface of the centrum spring two bony arches (n n), which are called the/' neural arches" or "neu- 328 MANUAL OF ZOOLOGY. rapophyses," because they form with the body a canal — the " neural canal " — which encloses the spinal cord. From the point where the neural arches meet behind, there is usually developed a longer or shorter spine, which is termed the " spi- nous process " or " neural spine " (s). From the neural arches there are also developed in the typical vertebra two processes (a a), which are known as the " articular " processes, or " zyga- pophyses." The vertebrae are united to one another partly by these, but to a greater extent by the bodies or " centra." From the sides of the vertebral body, at the point of junction with the neural arches, there proceed two lateral processes (d d\ which are known as the " transverse processes." (In the typical vertebra the transverse processes consist each of two pieces, an anterior piece or " parapophysis," and a posterior piece or " diapophysis.") These elements form the vertebra of the human anatomist, but the " vertebra " of the transcendental anatomist is completed by a second arch which is placed be- neath the body of the vertebra, and which is called the " hae- mal " arch, as it includes and protects the main organs of the circulation. This second arch is often only recognisable with great difficulty, as its parts are generally much modified, but a good example may be obtained in the human chest, or in the caudal vertebra of a bony fish. Fig. 117. — A, Lumbar vertebra of a Whale : c Body or centrum ; n n Neural arches ; s Neural spine ; a a Articular processes ; dd Transverse processes. B, Diagram of a thoracic vertebra : c Centrum ; n n Neural arches enclosing the neural canal ; .y Neural spine ; rr Ribs, assisting in the formation of the haemal arch ; // Costal car- tilages ; b Sternum, with haemal spine. (After Owen.) The haemal arch in the case of the human thorax (fig. 117, B) is formed by the ribs (r r) and the costal cartilages GENERAL CHARACTERS OF THE VERTEBRATA. 329 and is completed in front by the breast-bone or sternum (b), which in some cases — but not in man — develops a spine (the haemal spine), which corresponds to the neural spine on the opposite aspect of the vertebra. It follows from the above, that the typical vertebra consists of a central piece or body from which two arches are given off, one of which protects the great masses of the nervous system, and is therefore said to be " neural ; " whilst the other pro- tects the main organs of the circulation, and is therefore said to be " haemal." The correspondence of the typical bony segment or vertebra with the doubly tubular structure of the body in all Vertebrates is thus too obvious to require to be specially pointed out. As a general rule, the vertebral column is divisible into a number of distinct regions, of which the following are recog- nisable in man and in the higher Vertebrata : — i. A series of vertebras which compose the neck, and constitute the "cervical region" of the spine (fig. 118, c). 2. A number of vertebrae Fig. 118. — Skeleton of the Beaver (Castor fiber), showing the different regions of the vertebral column, c Cervical region ; d Dorsal region ; b Lumbar region ; s Sacrum ; t Caudal region. which usually carry well-developed ribs, and form the " dorsal region " (d). 3. A series of vertebrae which form the region of the loins, or "lumbar region" (b). 4. A greater or less 330 MANUAL OF ZOOLOGY. number of vertebrae which constitute the " sacral region," and are usually amalgamated or " anchylosed " together to form a single bone, the "sacrum" (s). 5. The spinal column is completed by a variable number of vertebrae which constitute the " caudal " region, or tail (/). As regards the skull of the Vertebrata, it has been thought advisable not to enter into any general details here, partly because the subject is one which can only be properly dis- cussed in a work specially devoted to Human or Comparative Anatomy, and partly because there is still much diversity of opinion as to the exact composition of the skull. There is, however, a very general concurrence of opinion that the skull is composed of a number of separate segments, and this is a point which it is important to remember. By Owen, and by many other competent authorities, these cranial segments are looked upon as being nothing more than so many vertebra, the neural canals of which are greatly expanded to enclose the brain, whilst the haemal arches are very greatly modified to serve different purposes. This view is not accepted by Hux- ley, but the general fact that the skull is composed of separate segments appears to be universally admitted. The only portion of the bony framework of the head which it is absolutely essential to understand, is the lower jaw or " mandible." The lower jaw is sometimes wanting, but when present, it consists in all Vertebrata of two halves or " rami," which are united to one another in front, and articulate separately with the skull behind. In many cases, each half, or " ramus," of the lower jaw consists of several pieces united to one another by sutures ; but in the Mammalia each ramus consists of no more than a single piece. The two rami are very variously connected with one another, being sometimes only joined by ligaments and muscles, sometimes united by cartilage or by bony suture, and sometimes fused or anchylosed with one another, so as to leave no evidence of their true composition. The mode by which each ramus of the lower jaw articulates with the skull also varies. In the Mammalia the lower jaw articulates with a cavity formed on what is known to human anatomists as the temporal bone ; but in Birds and Reptiles, the lower jaw articulates with the skull, not directly, but by the intervention of a special bone, known as the "quadrate bone" or " os quad- ratum" As regards the limbs of Vertebrates, whilst many differences ' exist, which will be afterwards noticed, there is a general agreement in the parts of which they are composed. As a rule, each pair of limbs is joined to the trunk by means of a GENERAL CHARACTERS OF THE VERTEBRATA. 331 series of bones which also correspond to one another in general structure. The fore-limbs, often called the " pectoral " limbs, are united with the trunk by means of a bony arch, which is called the " pectoral " or " scapular " arch ; whilst the hind- limbs are similarly connected with the trunk by means of the "pelvic arch." In giving a general description of the parts which compose the limbs and their supporting arches, it will be best to take the case of a Mammal, and the departures from this type will then be readily recognised. The pectoral or scapular arch consists usually of three bones, the " scapula " or shoulder-blade, the " coracoid," and the " clavicle " or collar-bone ; but in the great majority of the Mammals, the coracoid is anchylosed with the scap- ula, of which it forms a mere process. The scapula or shoulder-blade (fig. iig,s) is usually placed outside the ribs, and it forms, either alone or in conjunction with the other bones of the shoulder- girdle, the cavity with which the upper arm is articulated. The coracoid, though rarely existing as a distinct bone in the Mammals, plays a very important part in other Vertebrates, as we shall see hereafter. The clavicles are often wanting, or rudimentary, and they are the least essential elements of the scapular arch. The fore-limb proper consists, firstly, of a single bone which forms the upper arm, and which is known as the humerus (h). This arti- culates above with the shoulder-girdle, and is followed below by the fore-arm, which consists of two bones, called the radius and ulna. Of these the radius is chiefly concerned with carrying the hand. The radius and ulna are fol- lowed by the bones of the wrist, which are usually composed of several bones, and constitute what is called the carpus (d). These support the bones of the root of the hand, which vary in number, but are always more or less cylindrical in shape. They constitute what is called the metacarpus. The bones of the metacarpus carry the digits, Fig. 119. — Pectoral limb (arm) of Chimpanzee. (After Owen). c Cla- vicle ; s Scapula or shoul- der-blade ; h Humerus ; r Radius ; u Ulna ; d Bones of the wrist, or car- ?ns ; m Metacarpus ; p halanges of the fingers. 332 MANUAL OF ZOOLOGY. which also vary in number, but are composed each of from two to three cylindrical bones, which are known as the phalanges (p\ Homologous parts are, as a rule, readily recognisable in the hind-limb. The pelvic arch, by which the hind-limb is united with the trunk, consists of three pieces — the ilium, ischium, and pubes — which are usually anchylosed together, and form conjointly what is known as the innominate bone (fig. 120, /). In most Mammals, the two innominate bones unite in front by a ligamentous or cartilaginous union and they constitute, with the sacrum, what is known as the pelvis. The hind -limb proper consists of the following parts : — i. The thigh- bone or femur, corresponding with the humerus in the fore-limb. 2. The bones of the shank, corresponding with the radius and ulna of the fore-limb, and known as the tibia and fibula. Of these, the tibia is mainly or altogether con- cerned in carrying the foot, and it is thus shown to correspond to the radius, whilst the fibula corresponds to the ulna. ' 3. The small bones of the ankle, known as the tarsus, and varying in number in different cases. 4. A variable number of cylindrical bones (normally five), which are called the metatarsus, and which correspond to the metacarpus. 5. Lastly, the metatarsus carries the digits, which consist of from two to three small bones or phalanges, as Fig. 120. — Pelvic in the fore-limb. ofmb SpaJSee The digest™e system of Vertebrates will be (after Owen), i spoken of at greater length hereafter; but a /F±££$£! brief sketch may be given here of the general bone; t Tibia; s phenomena of digestion. All Vertebrate ani- Fibula; r Tarsus; , . , °, . , , r , m Metatarsus; p mals are provided with a mouth for the re- Sj!anges °f the cePtion of food, and in the great majority of cases the mouth is furnished with teeth, which are used sometimes merely to hold to the prey, but more commonly to cut and bruise the food, and thus render it capable of digestion. The food is also generally subjected in the mouth to the action of " salivary " glands, the se- cretion of which serves not only to moisten the food, and thus mechanically assist deglutition, but also to render soluble the starchy elements of the food. The food is next swallowed, or, in other words, is transferred from the mouth to the stomach, GENERAL CHARACTERS OF THE VERTEBRATA. 333 this being effected by a complicated arrangement of muscles, whereby the food is forced down the gullet (oesophagus) to the proper digestive cavity or stomach. In the stomach (fig. 121, s) the food is subjected to two sets of actions ; it is mechanically triturated and ground down by the constant contractions of the muscular walls of the stomach ; and it is subjected to the chemical action of a special fluid secreted by the stomach, and called the " gastric juice." This fluid has the power of reducing albuminoid substances to a soluble form, and by its action the food is ultimately reduced to a thick acid fluid, called the " chyme." Leaving the stomach by its lower aperture (the pylorus'), the chyme passes into the intestine, the first portion of which is divided into several sections, but is collectively known as the " small intestine." Here the chyme is sub- jected to the action of three other digestive fluids; the bile, secreted by a special organ, the liver; the pancreatic juice, secreted by another gland, the pancreas; and the intes- tinal juice, secreted by certain glands situated in the mucous membrane of the intestine itself. The result of the whole process is that the " chyme " is ultimately converted into a white, alkaline, milky fluid, which is called " chyle." The indigestible portions of the food pass from the small in- testine into a tube of larger dimen- sions, called the "large intestine." Such portions of the food as are still soluble, and capable of being employed in nutrition, are here taken up into the blood, the use- less remainder being ultimately ex- pelled by an anal aperture. The last portion of the large intestine is usually less convoluted than the rest, and is Called the "rectum." The fluid and originally soluble portions of the food, and the chyle which is formed in the process of digestion, are taken into the blood, the losses of which they serve to repair. Part of the nutritive materials of the food is taken up directly by the blood-vessels, and is conveyed by the " vena portae " to the j Stomach; sm Small intestine; Im Large intestine; r Rectum, terminating in the aperture of the anus. 334 MANUAL OF ZOOLOGY. liver, whence it ultimately reaches the great veins which go to the heart. The greater part, however, of the liquefied food, constituting the chyle, is taken up, not by the blood-vessels, but by a special set of tubes, which form a network in the walls of the intestine, and are known as the " lacteals." In these vessels, and in certain glands which are developed upon them, the chyle undergoes still further elaboration, and is made more similar in composition to the blood itself. All the lacteal vessels ultimately unite into one or more large vessels which open into one of the veins, so that all the chyle is thus finally added to the mass of the circulating blood. The blood, then, or nutrient fluid from which the tissues are built up, is formed in this way out of the materials which are taken into the alimentary canal as food. In all the Vertebrata, with the single exception of the Lancelet (Amphioxus), the blood is of a red colour when viewed in mass. This is due to Fig. 122. — Blood-corpuscles of Vertebrata. a Red blood-discs of man ; b Blood- discs of Goose ; c Crocodile ; d Frog ; e Skate. the presence in it of an incredible number of microscopical bodies, which are known as the " blood-corpuscles," the fluid in which these float being itself colourless (fig. 122). In all the Vertebrata the blood is distributed through the body by means of a system of closed tubes, which constitute the " blood-vessels ; " and in all except the Lancelet, the means of propulsion are derived from a contractile muscular cavity or " heart," furnished with valvular apertures. In the most complete form of circulation, as seen in Birds and Mammals, the heart is essentially a double organ, composed of two halves, each of which consists of two cavities, an auricle and a ventricle. The right side of the heart is wholly concerned with the " lesser " or pulmonary circulation, whilst the left side is concerned with driving the blood to all parts of the body (systemic circulation). The modifications of the circulat- ory process will be noticed in speaking of the different classes of Vertebrates, but a brief sketch may be given here of the circu- lation in its most complete form, as in a Mammal. In such a case, the venous or impure blood, which has circulated through the body and has parted with its oxygen, is returned by the great veins to the right auricle. From the right auricle (fig. 1 23, #) the GENERAL CHARACTERS OF THE VERTEBRATA. 335 blood passes by a valvular aperture into the right ventricle (v), whence it is driven through the pulmonary artery to the lungs. The right side of the heart is therefore wholly respiratory in its function. Having been sub- mitted to the action of the lungs, and having given off carbonic acid and taken up oxygen, the blood now becomes arterial, and is re- turned by the pulmonary veins to the left auricle (a1). From the left auricle the aerated blood passes through a valvular aperture into the left ventricle (vr), whence it is pro- pelled to all parts of the body by means of a great systemic vessel, the " aorta." The left side of the heart is therefore wholly occu- pied in carrying out the " greater" or systemic circulation. The purification of the blood is carried out in all Vertebrates by means of distinct respiratory organs, assisted to a greater or less extent by the skin. In the Fishes, and in the Amphibians to some extent, the process of respiration is carried on by means of branchicR or gills — that is, by organs adapted for breathing air dissolved in water. These are therefore often spoken of as " Branchiate " Vertebrates ; but the Amphibians always develop true lungs in the later stages of their existence. In the Reptiles, Birds, and Mammals, branchiae are never developed, and the respiration is always carried on by means of true lungs — that is, by organs adapted for breathing air directly. These are therefore often spoken of as the " Abranchiate " Vertebrates. The waste substances of the body— of which the most im- portant are water, carbonic acid, and urea — are got rid of by the skin, lungs, and kidneys. Under ordinary circumstances, the lungs are mainly occupied with the excretion of carbonic acid and watery vapour. The skin chiefly gets rid of superflu- ous moisture, but can also in many animals excrete carbonic acid as well. The kidneys are present in almost all Vertebrate Fig. 123.— Diagram of the circulation of a Mammal. The venous system is marked black ; the arterial system is left white. a Right auricle; v Right ventricle ; p Pulmonary artery, carrying venous blood to the lungs ; j>v Pulmonary veins carrying arterial blood from the lungs ; a' Left auricle ; •v' Left ventricle ; 6 Aorta, carrying arterial blood to the body; c Vena cava carrying venous blood to the heart. 336 MANUAL OF ZOOLOGY. animals, and their function is mainly to excrete water, and the nitrogenous substance known as urea. In the majority of cases the fluid excreted by the kidneys is conveyed to the ex- terior by means of two tubes known as the ureters, which empty themselves into a common receptacle, the urinary bladder. In some cases, however, the ureters open into the termination of the alimentary canal (rectum). The nervous system of Vertebrate animals usually exhibits a well-marked division into two parts — the cerebro-spinal system, and the sympathetic system. The cerebro-spinal system of nerves constitutes the great mass of the nervous system of Vertebrates, and usually exhibits a well-marked separation into spinal cord (myelon) and brain (encephalon). The pro- portion borne by the brain to the spinal cord differs much in different cases ; and in the Lancelet a brain can hardly be said to be present at all. As already said, the brain and spinal cord are always completely shut off from the visceral cavity, and they are placed upon the dorsal surface of the body. The nerves given off from the cerebro-spinal axis are symmetrically disposed on the two sides of the body, and they are mainly concerned with the functions of "animal " life — that is to say, with sensation and locomotion. The sympathetic system of nerves is unsymmetrically disposed to a greater or less extent, and presides mainly over the functions of " organic," or " vege- tative " life, being mainly concerned with regulating the func- tions of digestion and respiration, and the circulation of the blood. In its most fully developed form it consists of a double gangliated cord placed in the visceral cavity on the under sur- face of the spine, and of a series of nervous ganglia, united by nervous cords, and scattered mainly over the great viscera of the thorax and abdomen. The organs of the senses are well developed in the Vertebrata, and those appropriated to the senses of sight, hearing, smell, and taste are protected within bony cavities of the head. The perfection of the senses differs much in different cases, but they are probably never wholly wanting in any Vertebrate animal. There are cases in which vision must be of the most rudimen- tary character ; but even in these cases it is probable that there is a perception of light, even if there is no power of distinguish- ing objects. The only cases in which it would appear that vision is really altogether absent, are those of animals placed under the wholly abnormal condition of spending their exist- ence in darkness (such as the Proteus anguinus of the caves of Illyria). Smell, hearing, and taste are probably rarely, if ever, altogether absent in Vertebrates ; though in many cases their DIVISIONS OF THE VERTEBRATA. 337 organs are very rudimentary. Touch, or " tactile sensibility," is usually possessed to a greater or less degree by the entire surface of the body ; but the sense of touch is generally localised in certain particular parts, such as the appendages of the mouth, the lips, the tongue, or the digits. In all Vertebrata without exception reproduction is carried on by means of the sexes, and in all the sexes are in different individuals. No Vertebrate animal possesses the power of re- producing itself by fission or gemmation ; and in no case are composite organisms or colonies produced. Most of the Ver- tebrates are oviparous, that is to say, the ova are expelled from the body of the parent either before or very shortly after im- pregnation. In other cases, the eggs are retained within the body of the parent until the young are hatched, and in these cases the animals are said to be ovo-viviparous. In other cases, again, not only is the egg hatched within the parent, but the embryo is retained within the body of the mother until its de- velopment has been carried out to a greater or less extent; and these animals are said to be viviparous. DIVISIONS OF THE VERTEBRATA. — The sub-kingdom Verte- brata is divided into the five great classes of the Fishes (Pisces), Amphibians (Amphibia), Reptiles (Reptilia\ Birds (Aves), and Mammals (Mammalia). So far there is perfect unanimity; but when it is inquired into what larger sections the Vertebrata may be divided, there is much difference of opinion. Here, the divisions proposed by Professor Huxley will be adopted, but it is necessary that those employed by other writers should be mentioned and explained. One of the commonest methods of classifying the Vertebrata is to divide them into the two primary sections of the Branch- iata and Abranchiata. Of these, the Branchiate section in- cludes the Fishes and Amphibians, and is characterised by the fact that the animal is always provided at some period of its life with branchiae or gills. The Abranchiate section includes the Reptiles, Birds, and Mammals, and is characterised by the fact that the animal is never provided at any time of its life with gills. Additional characters of the Branchiate Vertebrates are, that the embryo is not furnished with the structures known as the amnion and allantois. Hence the Branchiate Vertebrates are often spoken of as the Anamniota and as the Anallantoidea. In the Abranchiate Vertebrates, on the other hand, the embryo is always provided with an amnion and allantois, and hence this section is spoken of as the Amniota or as the Allantoidea* * The amnion (fig. 116, C) is a membranous sac, containing a fluid — the liquor amnii — and completely enveloping the embryo. It consti- VOL. II. Y . 338 . MANUAL OF ZOOLOGY. : By Professor Owen the Vertebrata are divided into the two primary sections of the Hczmatocrya and the Hcematotherma, the characters of the blood being taken as the distinctive character. The Hamatocrya or Cold-blooded Vertebrates comprise the Fishes, Amphibia, and Reptiles, and are characterised by their cold blood, and imperfect circulation. The Hamatotherma or Warm-blooded Vertebrates comprise the Birds and the Mam- mals, and are characterised by their hot blood, four-chambered heart, and complete separation of the pulmonary and systemic circulations. The chief objection to this division lies in the separation which is effected between the Reptiles and the Birds, two classes which are certainly very nearly allied to one another. By Professor Huxley the Vertebrata are divided into the fol- lowing three primary sections : — I. ICHTHYOPSIDA. — This section comprises the Fishes and the Amphibians, and is characterised by the presence at some period of life of gills or branchiae, the absence of an amnion, the absence or rudimentary condition of the allantois, and the possession of nucleated red blood-corpuscles. II. SAUROPSIDA. — This section comprises the Birds and the Reptiles, and is characterised by the constant absence of gills, the possession of an amnion and allantois, the articulation of the skull with the vertebral column by a single occipital con- dyle; the composition of each ramus of the lower jaw of several pieces, and the articulation of the lower jaw with the skull by the intervention of an " os quadratum;" and, lastly, the posses- sion of nucleated red blood-corpuscles. III. MAMMALIA. — This section includes the single class of the Mammals, and agrees with the preceding in never possess- ing gills, and in having an amnion and allantois. The Mam- malia, however, differ from the Sauropsida in the fact that the skull articulates with the vertebral column by two occipital condyles ; each ramus of the lower jaw is simple, composed of tutes one of the so-called "foetal membranes," and is thrown off at birth. The allantois (fig. 116, C) is an embryonic structure, which is developed out of the middle or " vascular " layer of the germinal membrane. It ap- pears at first as a solid, pear-shaped, cellular mass, arising from the under part of the body of the embryo. In the process of development, the allan- tois increases largely in size, and becomes converted into a vesicle which envelops the embryo in part or wholly. It is abundantly supplied with blood, and is the organ whereby the blood of the foetus is aerated. The part of the allantois which is external to the body of the embryo is cast off at birth; but the portion which is within the body is retained and is con- verted into the urinary bladder. DIVISIONS OF THE VERTEBRATA. 339 a single piece, and the lower jaw is united with the temporal (squamosal) element of the skull, and is not articulated to a quadrate bone. There are special glands — the mammary glands — for the nourishment of the young for a longer or shorter period after birth, and the red blood-corpuscles are non- nucleated. 340 MANUAL OF ZOOLOGY. DIVISION I. ICHTHYOPSIDA. CHAPTER LIV. CLASS L— PISCES. THE first class of the Vertebrata is that of the Fishes (Pisces), which may be broadly defined as including Vertebrate animals which are provided with gills throughout the whole of life; the heart, when present, consists (with one exception) of a single au- ricle and a single ventricle ; the blood is cold; the limbs, when present, are in the form of fins, or expansions of the integument; and there is neither an amnion nor allantois in the embryo, unless the latter is represented by the urinary bladder. In form, Fishes are adapted for rapid locomotion in water, the shape of the body being such as to give rise to the least possible friction in swimming. To this end also, as well as for purposes of defence, the body is usually enveloped with a coating of scales developed in the inferior or dermal layer of the skin. The more important modifications in the form of these dermal scales are as follows : I. Cycloid scales (fig. 124, a), consisting of thin, flexible, horny scales, circular or elliptical in shape, and having a more or less completely smooth outline. These are the scales which are character- istic of most of the ordinary bony fishes. II. Ctenoid scales (fig. 1 24, b], also consisting of thin horny plates, but having their posterior margins fringed with spines, or cut into comb-like projections. III. Gan- oid scales, composed of an inferior layer composed of bone, covered by a superficial layer of hard po- lished enamel (the so-called " ganoine "). These scales (fig. Fig. 124. — Scales of different fishes. a Cycloid scale (Pike): b Ctenoid scale (Perch) ; c Placoid scale (Thornback); d Ganoid scales (Palteoniscus). CHARACTERS OF FISHES. 341 124, d) are usually much larger and thicker than the ordinary scales, and though they are often articulated to one another by special processes, they only rarely overlap. IV. Placoid scales, consisting of detached bony grains, tubercles, or plates, of which the latter are not uncommonly armed with spines (fig. 124, c). In most fishes there is also to be observed a line of peculiar scales, forming what is called the " lateral line." Each of the scales in this line is perforated by a tube leading down to a longitudinal canal which runs along the side of the body, and is connected with cavities in the head. The function of this singular system has been ordinarily believed to be that of se- creting the mucus with which the surface of the body is covered; but it seems to be more probably sensory in function, and to be connected with the sense of touch. As regards their true osseous system or endoskeleton, Fishes vary very widely. In the Lancelet there can hardly be said to be any skeleton, the spinal cord being simply supported by the gelatinous notochord, which remains throughout life. In others the skeleton remains permanently cartilaginous \ in others it is partially cartilaginous and partially ossified ; and, lastly, in most modern fishes it is entirely ossified or converted into bone. Taking a bony fish (fig. 125) as in this respect a typical example of the class, the following are the chief points in the osteology of a fish which require notice : — , bones; it Interspinous bones; rRibs; j Spinous processes of vertebrae ; h Haemal processes of vertebras. The vertebral column in a bony fish consists of vertebras, which are hollow at both ends, or biconcave, and are techni- 342 MANUAL OF ZOOLOGY. cally said to be " amphicoelous." The cup-like margins of the vertebral bodies are united by ligaments, and the cavities formed between contiguous vertebras are rilled with the gela- tinous remains of the notochord. This elastic gelatinous sub- stance acts as a kind of ball-and-socket joint between the bodies of the vertebrae, thus giving the whole spine the extreme mo- bility which is requisite for animals living in a watery medium. The ossification of the vertebrae is often much more imperfect than the above, but in no case except that of the Bony Pike (Lepidosteus] is ossification carried to a greater extent than this. In this fish, however, the vertebral column is composed of "opisthocoelous" vertebrae — that is, of vertebrae the bodies of which are concave behind and convex in front. The entire spinal column is divisible into not more than two distinct re- gions, an abdominal and a caudal region. The abdominal vertebrae possess a superior or neural arch (through which passes the spinal cord), a superior spinous process (neural spine), and two transverse processes to which the ribs are usually attached. The caudal vertebrae (fig. 125) have no marked transverse pro- cesses ; but, in addition to the neural arches and spines, they give off an inferior or hczmal arch below the body of the verte- bra, and the haemal arches carry inferior spinous processes (haemal spines). The ribs of a bony fish are attached to the transverse pro- cesses, or to the bodies of the abdominal vertebrae, in the form of slender curved bones which articulate with no more than one vertebra each, and that only at a single point. Unlike the ribs of the higher Vertebrates, the ribs do not enclose a thoracic cavity, but are simply embedded in the muscles which bound the abdomen. Usually each rib gives off a spine-like bone, which is directed backwards amongst the muscles. Inferiorly the extremities of the ribs are free, or are rarely united to der- mal ossifications in the middle line of the abdomen ; but there is never any breast-bone or sternum properly so called. The only remaining bones connected with the skeleton of the trunk are the so-called i?iterspinous bones (fig. 125, ii). These form a series of dagger-shaped bones plunged in the middle line of the body between the great lateral muscles which make up the greater part of the body of a fish. The internal ends or points of the interspinous bones are attached by ligament to the spinous processes of the vertebrae ; whilst to their outer ends are articulated the "rays " of the so-called " median " fins, which will be hereafter described. As a rule, there is only one interspinous bone to each spinous process, but in the Flat-fishes (Sole, Turbot, &c.) there are two. CHARACTERS OF FISHES. 343 Beside the fins which represent the limbs (pectoral and central fins), fishes possess other fins placed in the middle line )f the body, and all of these alike are supported by bony spines or "rays," which are of two kinds, termed respectively " spi- nous rays " and " soft rays." The " spinous rays " are simple bony spines, apparently composed of a single piece each, but really consisting of two halves firmly united along the middle line. The " soft rays " are composed of several slender spines proceeding from a common base, and all divided transversely into numerous short pieces. The soft rays occur in many fishes in different fins, but they are invariably found in the caudal fin or tail (fig. 125, c}. The rays of the median fins, whatever their character may be, always articulate by a hinge-joint with the heads of the interspinous bones. The skull of the bony fishes is an extremely complicated structure, and it is impossible to enter into its composition here. The only portions of the skull which require special mention are the bones which form the gill-cover or operculum, Fig. 126. — Skull of Cod (Morrhua vulgaris) — Cuvier. a Urohyal ; b Basihyal ; c Ceratohyal ; d Branchiostegal rays; p Prae-operculum ; o Operculum proper J J Sub- operculum ; i Inter-operculum ; m Mandible ; « Inter-maxillary bone. and the hyoid bone with its appendages. For reasons con- nected with the respiratory process in fishes, as will be after- 344 MANUAL OF ZOOLOGY. wards seen, there generally exists between the head and the scapular arch a great cavity or gap on each side, within which are contained the branchiae. The cavity thus formed opens externally on each side of the neck by a single vertical fissure or " gill-slit," closed by a broad flap, called the " gill-cover " or "operculum," and by a membrane termed the " branchi- ostegal membrane." The gill-cover (fig. 126, /, o, s, i) is composed of a chain of broad flat bones, termed the opercular bones. Of these, the innermost articulates with the skull (tympano-mandibular arch), and is called the " prae-operculum ; " the next is a large bone called the "operculum" proper; and the remaining two bones, called respectively the "sub-operculum" and "inter-operculum," form, with the operculum proper, the edge of the gill-cover. These various bones are united together by membrane, and they form collectively a kind of movable door, by means of which the branchial chamber can be alternately opened and shut. Besides the gill-cover, however, the branchial chamber is closed by a membrane called the " branchiostegal mem- brane," which is attached to the os hyoides. The membrane is supported and spread out by a number of slender curved spines, which are attached to the lateral branches of the hyoid bone, act very much as the ribs of an umbrella, and are known as the "branchiostegal rays" (fig. 126, d). The hyoid arch of fishes is attached to the temporal bones of the skull by means of two slender styliform bones, which correspond to the styloid processes of man, and are called the " stylohyal" bones (fig. 127, f). The rest of the hyoid arch is composed of a central portion and two lateral branches. Each branch is composed of the following parts : — i. A triangular bone attached above to the stylohyal, and termed the " epihyal bone" (fig. 127, e } ; 2. A much longer bone, known as the " ceratohyal " (d). The central portion of the hyoid arch is made up of two small polyhedral bones — the " basihyals " (b). From the basihyal there extends forwards in many fishes a slender bone, which supports the tongue, and is termed the "glossohyal" or "lingual" bone (a). There is also another compressed bone, which extends backwards from the basihyals, and which is known as the " urohyal bone " (c). This last- mentioned bone is of importance, as it often extends back- wards to the point of union of the coracoid bones, and thus forms the isthmus which separates the two branchial apertures. From the outer margins of the epihyal and ceratohyal bones on each side arise the slender curved " branchiostegal rays," which have been previously mentioned. There are usually CHARACTERS OF FISHES. 345 seven of these on each side. Above the urohyal, and attached in front to the body of the os hyoides, is a chain of bones, placed one behind the other, and termed by Owen the " basi- Fig. 127. — Os hyoides, branchiostegal rays, and scapular arch of the Perch (after Cuvier). « Supra-scapula ; s Scapula ; co Coracoid ; cl Supposed representative of the clavicle ; a Glossohyal bone ; b Basihyal ; c Urohyal ; d Ceratohyal ; e Epihyal ; yStylohyal; br Branchial arches; t Branchiostegal rays. branchial bones." Springing from these are four bony arches — the " branchial arches " — which proceed upwards to be con- nected superiorly by ligament with the under surface of the skull. The branchial arches — as will be subsequently de- scribed— carry the branchiae, and each is composed of two main pieces, termed respectively the " cerato-branchial " and " epi-branchial " bones. The second and third arches are con- nected with the skull by the intervention of two small bones, often called the " superior pharyngeal bones," but termed by Owen the " pharyngo-branchial " bones. The limbs of fishes depart considerably from the typical form exhibited in the higher Vertebrates. One or both pairs of limbs may be wanting, but when present the limbs are always in the form of fins — that is, of expansions of the integument 346 MANUAL OF ZOOLOGY. strengthened by bony or cartilaginous fin-rays. The anterior limbs are known as the pectoral fins, and the posterior as the ventral fins; and they are at once distinguished from the so-called " median " fins by being always symmetrically dis- posed in pairs. Hence they are often spoken of as the paired fins. The scapular arch (figs. 127, 128) supporting the pec- toral limbs is usually joined to the skull (occipital bone), and consists of the following pieces on each side : — i. The supra- scapula (ss) ; 2. The scapula (s), articulating with the former; and, 3. The coracoid (co)y attached above with the scapula, and c u Fig. 128. — Pectoral limbs of Fishes (after Owen). A, Cod (Morrhua vulgaris) ; B, Angler (Lophius). ss Supra-scapula ; s Scapula ; co Coracoid ; r Radius ; « Ulna ; cc Carpal bones ; f Fin-rays, representing the metacarpus and phalanges of the fingers. united below, by ligament or suture, with the coracoid of the opposite side, thus completing the pectoral arch. Lastly, there is often another bone, sometimes single, but oftener of two CHARACTERS OF FISHES. 347 pieces, attached to the upper end of the coracoid, and this is believed to represent the collar-bone or clavicle.* The fore-limb possesses in a modified form most of the bones which are present in the higher Vertebrata. The hum- erus, or bone of the upper arm, is usually wanting, or it is alto- gether rudimentary. A radius and ulna (fig. 128, r, u) are usually present, and are followed by a variable number of bones, which represent the carpus, and some of which some- times articulate directly with the coracoid. The carpus is fol- lowed by the " rays " of the fin proper, these representing the metacarpal bones and phalanges. The hind-limbs or " ventral fins" are wanting in many fishes, and they are less developed and less fixed in position than are the pectoral fins. In the ventral fins no representatives of the tarsus, tibia and fibula, or femur, are ever developed. The rays of the ventral fins — representing the metatarsus and the phalanges of the toes — unite directly with a pelvic arch, which is composed of two sub-triangular bones, united in the middle line and believed to represent the ischia. The imperfect pelvic arch, thus constituted, is never united to the vertebral column in any fish. In those fishes in which the ventral fins are " abdominal" in position (z>., placed near the hinder end of the body) the pelvic arch is suspended freely amongst the muscles. In those in which the ventral fins are "thoracic" or "jugular" (i.e., placed beneath the pectoral fins, or on the sides of the neck) the pelvic arch is attached to the coracoid bones of the scapular arch, and is therefore wholly removed from its proper vertebra. In addition to the pectoral and ventral fins — the homologues of the limbs — which may be wanting, fishes are furnished with certain other expansions of the integument, which are "median" in position, and must on no account be confounded with the true "paired" fins. These median fins are variable in number, and in some cases there is but a single fringe running round the posterior extremity of the body. In all cases, however, the median fins are " azygous " — that is to say, they occupy the middle line of the body, and are not sym- metrically disposed in pairs. Most commonly, the median fins consist of one or two expansions of the dorsal integument, called the "dorsal fins" (fig. 129, d, d') ; one or two on the ventral surface near the anus — the " anal fins " (fig. 129, a} • and a broad fin at the extremity of the vertebral column, called the * These are the views entertained by Owen as to the composition and nature of the pectoral arch of fishes, but they are dissented from by Mr Parker, one of the greatest living authorities on this subject. MANUAL OF ZOOLOGY. " caudal fin " or tail (c). In all cases, the rays which support the median fins are articulated with the so-called interspinous bones, which have been previously described. Fig. 129. ^Outline of a fish (Percct granulata), showing the paired and unpaired fins. p One of the pectoral fins ; v One of the ventral fins ; d First dorsal fin ; d' Second dorsal fin ; a Anal fin ; c Caudal fin. The caudal fin or tail of fishes is always set vertically at the extremity of the spine, so as to work from side to side, and it is the chief organ of progression in the fishes. In its vertical position and. in the possession of fin-rays, it differs altogether from the horizontal integumentary expansion which constitutes the tail of the Whales, Dolphins, and Sirenia (Dugong and Manatee). In the form of the tail fishes exhibit two very distinct types of structure, termed respectively the "homocercal" and " hetero- cercal" type of tail (fig. 130). The homocercal tail is the one which most commonly occurs in our modern fishes, and it is characterised by the fact that the two lobes of the tail are equal, and the vertebral column, instead of being prolonged into the upper lobe of the tail, stops short at its base. In the heterocercal tail, on the other hand, the vertebral column is prolonged into the upper lobe of the tail, so that the tail becomes unequally lobed, its greater portion being placed Fig. 130.— Tails of different fishes. a Homocercal tail (Sword-fish); b Heterocercal tail (Sturgeon). CHARACTERS OF FISHES. ,4 349 below the spine. Even where the vertebral column is not pro- longed into the upper lobe, the tail may nevertheless become heterocercal, in consequence of a great development of the haemal spines as compared with the neural spines of the vertebrae. The process of respiration in all fishes is essentially aquatic, and is carried on by means of branchial plates or tufts devel- oped upon the posterior visceral arches, which are persistent, and do not disappear at the close of embryonic life, as they do in other Vertebrates. In the Lancelet alone, respiration is effected partly by branchial filaments placed round the com- mencement of the pharynx, and partly by the pharynx itself, which is greatly enlarged, and has its walls perforated by a series of transverse ciliated fissures. The arrangement and structure of the branchiae differs a good deal in the different orders of Fishes, and these modifications will be noticed sub- sequently. In the meanwhile it will be sufficient to give a brief description of the branchial apparatus in one of the bony fishes. In such a fish, the branchiae are connected with the hyoid arch, and are situated in two special chambers, situated one on each side of the neck. The branchiae are carried upon the outer convex sides of what have been already described as the "branchial arches ;" that is to say, upon a series of bony arches which are connected with the hyoid arch inferiorly, and are united above with the base of the skull. The internal concave sides of the branchial arches are usually furnished with a series of processes, constituting a kind of fringe, the function of which is to prevent foreign substances finding their way amongst the branchiae, and thus interfering with the proper action of the respiratory organs. The branchiae, themselves, usually have the form of a double series of cartilaginous leaflets or laminae. The branchial laminae are flat, elongated, and pointed in shape, and they are covered with a highly vascular mucous membrane, in which the branchial capillaries ramify. The blood circulates through the branchial laminae, and is here subjected to the action of aerated water, whereby it is oxygen- ated. The water is constantly taken in at the mouth by a movement analogous to swallowing, and it gains admission to the branchial chambers by means of a series of clefts or slits, the " branchial fissures," which are situated on both sides of the pharynx. Having passed over the gills, the deoxygenated water makes its escape posteriorly by an aperture called the " gill-slit " or " opercular aperture," one of which is situated on each side of the neck. As we have seen before, the gill-slit is closed in front by a chain of flat bones, collectively consti- 350 MANUAL OF ZOOLOGY. tuting the " gill-cover " or " operculum ; " and the gill-covers are finally completed by a variable number of bony spines — the " branchiostegal rays" — which articulate with the hyoid arch, and support a membrane — the " branchiostegal membrane." The heart of Fishes is, properly speaking, a branchial or respiratory heart. It consists of two cavities, an auricle and a ventricle (fig. 131, a, v), and the course of the circulation is as follows : — The venous blood de- rived from the liver and from the body generally is poured by the vena cava into the auricle (a), and from this it is propelled into the ventricle (v). From the ventricle arises a single aortic arch (the right), and the base of this is usually dilated into a cavity or sinus, called the "bulbus arteriosus " (m). The arterial bulb is sometimes covered with a special coat of striated muscular fibres, and is provided with several transverse rows of valves. In these cases, the bulbus acts as a kind of continuation of the ventricle, being capable of rhythmical contractions. The blood is driven by the ventricle through the branchial artery (ri) to the gills, through which it is dis- tributed by means of the branchial vessels, the number of which varies (there are three on each side in a few fishes, four in most of the bony fishes, five in the Skates and Sharks, and six or seven in the Lampreys). The aerated blood which has passed through the gills is not returned to the heart, but is driven from the branchiae through all parts of the body; the propulsive force necessary for this being derived chiefly from the heart, assisted by the contractions of the vol- untary muscles. In some fishes (as in the Eel) the return of the blood to the heart is assisted by a rhythmically contractile dilatation of the caudal vein. The essential peculiarity, then, of the circulation of fishes depends upon this — that the arterial- ised blood returned from the gills is propelled through the sys- temic vessels of the body, without being sent back to the heart. Fig. 131. — Diagram of the cir- culation in a fish. a. Auricle, receiving venous blood from the body ; v Ventricle ; in Bulbus arteriosus, at the base of the branchial artery; n Branchial artery, carrying the venous blood to the gills (bb~); c Aorta, carrying the arterial- ised blood to all parts of the body. CHARACTERS OF FISHES. 351 The Lancelet (Amphioxus}, alone of all Fishes, has no special heart, and the circulation is effected by contractile dilatations developed upon several of the blood-vessels. In the Mud-fish (Lepidosiren) the heart consists of two auricles and a single ventricle. The blood-corpuscles of Fishes are nucleated (fig. 122, e), and the blood is red in all except the Amphioxus. As regards the digestive system of Fishes there is not much of peculiar importance. The mouth is usually furnished with a complicated series of teeth, which, in the Bony Fishes, are not only developed upon the jaws proper, but are also situated upon other bones which enter into the composition of the buccal cavity (such as the palate, the pterygoids, vomer, branchial arches, the glossohyal bone, &c.) The oesophagus is usually short and capacious, and generally opens into a large and well-marked stomach. The pyloric aperture of the stomach is usually furnished with a valve, and behind it there is usually a number (from one to sixty) of blind appendages, termed the " pyloric caeca." These are believed to represent the pancreas, but there may be a recognisable pancreas either alone or in addition to the pyloric caeca. The intestinal canal is a longer or shorter, more or less convoluted tube, the absorbing surface of which, in certain fishes, is largely increased by a spiral reduplicature of the mucous membrane, which winds like a screw in close turns from the pylorus to the anus. The liver is usually large, soft, and oily, and a gall-bladder is almost universally present ; but in the Amphioxus the liver is doubt- fully represented by a hollow sac-like organ. The kidneys of fishes are usually of great size, and form two elongated organs, which are situated beneath the spine, and extend along the whole length of the abdominal cavity. The ureters often dilate, and form a species of bladder, the doubtful representative of the allantois. Whilst the respiration of all fishes is truly aquatic, most of them are, nevertheless, furnished with an organ which is doubtless the homologue of the lungs of the air-breathing Vertebrates. This — the " air " or " swim bladder " — is a sac containing gas, situated beneath the alimentary tube, and often communicating with the gullet by a duct. In the great majority of fishes the functions of the air-bladder are certainly hydrostatic — that is to say, it serves to maintain the necessary accordance between the specific gravity of the fish and that of the surrounding water. In the singular Mud-fishes, however, it acts as a respiratory organ, and is therefore not only the homologue, but also the analogue, of the lungs of the higher 35 2 MANUAL OF ZOOLOGY. Vertebrates. In most fishes the air-bladder is an elongated sac with a single cavity, but in many cases it is variously sub- divided by septa. In the Mud-fish the air-bladder is composed of two sacs, completely separate from one another, and divided into a number of cellular compartments. The duct leading in many fishes from the air-bladder (ductus pneumaticus) opens into the oesophagus, and is the homologue of the wind-pipe (trachea). The air contained in the swim-bladder is composed mainly of nitrogen in most fresh-water fishes, but in the sea- fishes it is mainly made up of oxygen. The nervous system of Fishes is of an inferior type of organ- isation, the brain being of small size, and consisting mainly of ganglia devoted to the special senses. As regards the special senses, there is one peculiarity which deserves special notice, and this is the conformation of the nasal sacs. The cavity of the nose is usually double, and is lined by an olfactory mem- brane, folded so as to form numerous plicae. Anteriorly, the water is admitted into the nasal sacs by a single or double nostril, usually by two apertures ; but posteriorly the nasal sacs are closed, and do not communicate with the pharynx by any aperture. The only exceptions to this statement are to be found in the Myxinoids and in the Leprdosiren. The essential portion of the organ of hearing (labyrinth) is present in almost all fishes, but in none is there any direct communi- cation between the ear and the external medium. As regards their reproductive system, fishes are, for the most part, truly oviparous, the ovaries being familiarly known as the " roe." The testes of the male are commonly called the " soft roe " or " milt." The products of the reproductive organs are often set free into the peritoneal cavity, ultimately finding their way to the external medium, either by means of an abdominal pore (or pores), or by being taken up by the open mouths of the " Fallopian tubes." In other cases the generative pro- ducts are directly conveyed to the exterior by the proper ducts of the reproductive organs. PH ARYNGOBR ANCHII. 353 DIVISIONS OF FISHES. CHAPTER LV. PHARYNGOBRANCHII AND MARSIPOBRANCHIL THE class Pisces has been very variously subdivided by dif- ferent writers ; but the classification here adopted is the one proposed by Professor Huxley, who divides the class into the following six orders, in the subdivisions of which Professor Owen has been followed : — ORDER I. PHARYNGOBRANCHII (= Cirrostomi, Owen; and Leptocardia, Miiller). — This order includes but a single fish, the anomalous Amphioxus lanceolattis, or Lancelet, the organ- isation of which differs in almost all important points from that of all the other members of the class. The order is defined by the following characters, which, as will be seen, are mostly negative : — No skull is present, nor lower jaw (mandible), nor limbs. The notochord is persistent ; and there are no verte- bral centra nor arches. No distinct brain nor auditory organs are present. In place of a distinct heart, pulsating dilatations are developed upon several of the great blood-vessels. The blood is pale. The mouth is in the form of a longitudinal fissure, surrounded by filaments or cirri. The walls of the pharynx are perforated by numerous clefts or fissures, the sides of which are ciliated, the whole exercising a respiratory function. The Lancelet is a singular little fish which is found burrow- ing in sandbanks, in various seas, but especially in the Medi- terranean. The body is lanceolate in shape, and is provided with a narrow membranous border, of the nature of a median fin, which runs along the whole of the dorsal and part of the ventral surface, and expands at the tail to form a lancet-shaped caudal fin. No true paired fins, representing the anterior and posterior limbs, are present. The mouth is a longitudinal fissure, situated at the front of the head, and destitute of jaws. It is surrounded by a cartilaginous ring, composed of many pieces, which give off prolongations, so as to form a number of cartilaginous filaments or " cirri " on each side of VOL. n. z 354 MANUAL OF ZOOLOGY. the mouth. (Hence the name of Cirrostomi, proposed by Professor Owen for the order.) The throat is provided on each side with vascular lamellae, which are believed by Owen Fig. 132. — Diagram of the Lancelet (Antphioxus). m Mouth, surrounded by cartila- ginous cirri ; / Greatly dilated pharynx, perforated by ciliated clefts ; i Intestine, terminating in anus (a) ; h Haemal system, with pulsating dilatations ; ch Notochord ; n Spinal cord. to perform the function of free branchial filaments. The mouth leads into a dilated chamber, which is believed to represent the pharynx, and is termed the " pharyngeal " or " branchial sac." It is an elongated chamber, the walls of which are strengthened by numerous cartilaginous filaments, between which is a series of transverse slits or clefts, the whole covered by a richly cili- ated mucous membrane. This branchial dilatation has given rise to the name Branchiostoma, often applied to the Lancelet. Posteriorly the branchial sac opens into an alimentary canal, to which is appended a long and capacious sac or caecum, which is believed to represent the liver. The intestinal tube termi- nates posteriorly by a distinct anus. Respiration is effected by the admission of water taken in by the mouth into the branchial sac, having previously passed over the free branchial filaments before mentioned. The water passes through the slits in the branchial sac, and thus gains access to the abdominal cavity, from which it escapes by means of an aperture with contractile margins situated a little in front of the anus, and called the " abdominal pore." There is no distinct heart, and the circulation is entirely effected by means of several rhythmi- cally contractile dilatations which are developed upon several of the great blood-vessels. The blood itself is colourless. No kidneys have as yet been discovered, and there is no lymphatic system. There is no skeleton properly so called. In place of the vertebral column, and constituting the whole endoskeleton, is the semi-gelatinous cellular notochord, enclosed in a fibrous sheath, and giving off fibrous arches above and below. The notochord is, further, peculiar in this, that it is prolonged quite to the anterior end of the body, whereas in all other Vertebrates MARSIPOBRANCHII. 355 it stops short at the pituitary fossa. There is no cranium, and the spinal cord does not expand anteriorly to form a distinct cerebral mass. The brain, however, may be said to be repre- sented, since the anterior portion of the nervous axis gives off nerves to a pair of rudimentary eyes, and another branch to a ciliated pit, believed to represent an olfactory organ. The generative organs (ovaria and testes) are not furnished with any efferent ducts (oviduct or vas deferens). The generative products, therefore, must be admitted into the abdominal cavity, and gain the external medium by the " abdominal pore." ORDER II. MARSIPOBRANCHII (= Cyclostomi, Owen ; and Cyclostomata, Miiller). — This order includes the Lampreys (Petromyzonida) and the Hag-fishes (Myxinidiz\ and is de- fined by the following characters : — The body is cylindrical, worm -like, and destitute of limbs. The skull is cartilaginous, without cranial bones, and having no lower jaw (mandible). The notochord is persistent, and there are either no vertebral centra, or but the most rudimentary traces of them. The heart consists of one auricle and one ventricle, but the branchial artery is not furnished with a bulbus arteriosus. The gills are sac-like, and are not ciliated. The type of piscine organisation displayed in the Marsipo- branchii is of a very low grade, as indicated chiefly by the persistent notochord without vertebral centra, the absence of any traces of limbs, the absence of a mandible, and the struc- ture of the gills. Fig. 133. — A, Lamprey (jPetromyzoti), showing the sucking-mouth and the apertures of the gill-sacs. B, Diagram to illustrate the structure of the gills in the Lamprey : a Pharynx ; b Tube leading from the pharynx into one of the gill-sacs ; c One of the gill-sacs, showing the lining membrane thrown into folds ; d External opening of the gill-sac. (In reality the gill-sacs do not open directly into the pharynx, but into a common respiratory tube, which is omitted for the sake of clearness.) Both the Lampreys (fig. 133, A) and the Hag-fishes are vermiform, eel-like fishes, which agree in possessing no paired fins, to represent the limbs, but in having a median fin running 356 MANUAL OF ZOOLOGY. round the hinder extremity of the body. The skeleton re- mains throughout life in a cartilaginous condition, the chorda dorsalis is persistent, and the only traces of bodies of vertebrae are found in hardly perceptible rings of osseous matter de- veloped in the sheath of the notochord. The neural arches of the vertebrae, enclosing the spinal cord, are only represented by cartilaginous prolongations. The mouth in the Hag-fish (Myxine) is of a very remarkable character, and enables it to lead a very peculiar mode of life. It is usually found, namely, embedded in the interior of some other larger fish, into which it has succeeded in penetrating by means of its singular dental apparatus. The mouth is sucker-like, destitute of jaws, but provided with tactile filaments or cirri. In the centre of the palate is fixed a single, large, recurved fang, which is firmly attached to the under surface of the cranium. The sides of this fang are strongly serrated, and it is by means of this that the Hag-fish bores its way into its victim, having previ- ously attached itself by its sucker-like mouth. In the Lam- preys the mouth has also the form of a circular cup or sucker, and is also destitute of jaws; but in addition to the palatine fang of the Myxine, the margins of the lips bear a number of horny processes, which are not really true teeth, but are hard structures developed in the labial mucous membrane. The tongue, also, is armed with serrated teeth, and acts as a kind of piston ; so that the Lampreys are in this manner enabled to attach themselves firmly to solid objects. A very remarkable peculiarity in the Hag-fishes, and one very necessary to remember, is found in the structure of the nasal sacs. In all fishes, namely, except these and the Mud- fishes (Lepidosiren\ the nasal sacs are closed behind, and do not open posteriorly into the throat. In the Myxinoids, how- ever, such a communication exists, and the nasal sac — for there is only one — is placed in communication with the cavity of the mouth by means of a canal which perforates the palate. In front the nasal cavity communicates with the external me- dium by a second tube, which opens on the top of the head by a single aperture, which is often called the " spiracle," and which is in reality an unpaired nostril. In the Lampreys, on the other hand, the single nasal sac has the same structure as in the typical fishes — that is to say, it is closed behind, and does not communicate in any way with the cavity of the mouth. Another very remarkable point in the Hag-fishes and Lam- preys is to be found in the structure of the gills, from which the name of the order is derived. In the Lampreys, in place TELEOSTEI. 357 of the single gill-slit, covered by a gill-cover, as seen in the ordinary bony fishes, the side of the neck, when viewed ex- ternally, exhibits six or seven round holes placed far back in a line on each side (fig. 133, A). In the Hag-fishes the external apertures of the gills are reduced to one on each side, placed below the head ; but the internal structure of the gills is the same in both cases. In both the Lampreys and the Hag-fishes, namely, the gills are in the form of sacs or pouches (fig. i33,B), the mucous membrane of which is thrown into folds or plaits like the leaves of a book, over which the branchial vessels ramify. Internally the sacs communicate with the cavity of the pharynx, either directly or by the intervention of a common respiratory tube. It follows from this, that the gill-pouches on the two sides, with their included fixed branchial laminae, com- municate freely with one another through the pharynx. The object of this arrangement appears to be mainly that of ob- viating the necessity of admitting water to the gills through the mouth, as is the case with the ordinary bony fishes. These fishes are in the habit of fixing themselves to foreign objects by means of the suctorial mouth ; and when in this position it is, of course, impossible that they can obtain the necessary water of respiration through the mouth. As the branchial pouches, however, on the two sides of the neck communicate freely with one another through the pharynx, water can readily pass in and out. This, in the Lampreys, is further assisted by a kind of elastic cartilaginous framework upon which the respiratory apparatus is supported, and which acts somewhat like the ribs of the higher Vertebrata. Water can also be admitted to the pharynx, and thence to the branchial sacs, by means of a tube which leads from the pharynx to an aperture placed on the top of the head. The Lampreys are, some of them, inhabitants of rivers ; but the great Sea-lamprey (Petromyzon marinus) only quits the salt water in order to spawn. The Hag- fish (Myxine glutinosa) is an inhabitant of the North Sea, and is commonly captured on the Norwegian coast. CHAPTER LVI. TELEOSTEI. ORDER III. TELEOSTEI. — This order includes the great ma- jority of fishes in which there is a well-ossified endoskeleton, 358 MANUAL OF ZOOLOGY. and it corresponds very nearly with Cuvier's division of the " osseous" fishes. The Teleostei are defined as follows : — The skeleton is usually well ossified ; the cranium is provided with cranial bones ; and a mandible is present ; whilst the vertebral column almost always consists of more or less completely ossi- fied vertebrae. The pectoral arch has a clavicle ; and the two pairs of limbs, when present, are in the form of fins supported by rays. The gills are free, pectinated or tufted in shape ; a bony gill-cover and branchiostegal rays being always devel- oped. The branchial artery has its base developed into a bul- bus arteriosus ; but this is never rhythmically contractile, and is separated from the ventricle by no more than a single row of valves. The order Teleostei comprises almost all the common fishes ; and it will be unnecessary to dilate upon their structure, as they were taken as the types of the class in giving a general description of the Fishes. It may be as well, however, to recapitulate very briefly some of the leading characters of the order. I. The skeleton, instead of remaining throughout life more or less completely cartilaginous, is now always more or less thoroughly ossified. The notochord is not persistent, and the vertebral column, though sometimes cartilaginous, consists of a number of vertebrae. The bodies of the vertebrae are what is called "amphicoelous" — that is to say, they are concave at both ends. It follows from this, that between each pair of vertebrae there is formed a doubly-conical cavity, and this is filled with the cartilaginous or semi-gelatinous remains of the notochord. By this means an extraordinary amount of flexi- bility is given to the entire vertebral column. In no fish except the Bony Pike (which belongs to the order Ganoidei) is the ossification of the vertebral centra carried further than this. The skull is of an extremely complicated nature, being com- posed of a number of distinct cranial bones ; and a mandible or lower jaw is invariably present. II. The anterior and posterior pairs of limbs are usually, but not always, present, and when developed they are always in the form of fins. The fins may be supported by " spinous" or " soft" rays, of which the former are simple undivided spines of bone, whilst the latter are divided transversely into a num- ber of short transverse pieces, and also are broken up into a number of longitudinal rays proceeding from a common root. (The Fishes with soft rays in their paired fins are termed " Malacopterygii" — those with spinous rays, " Acant/wpterygii") III. Besides the paired fins, representing the limbs, there is TELEOSTEI. 359 a variable number of unpaired or azygous integumentary ex- pansions, which are known as the "median fins." When fully developed (fig. 129), they consist of one or two fins on the back — the " dorsal " fins ; one or two on the ventral surface — the " anal " fins ; and one clothing the posterior extremity of the body — the " caudal" fin. The caudal fin is set vertically, and not horizontally, as in the Whales and Dolphins; and in all the bony fishes its form is " homocercal" — that is, it consists of two equal lobes, and the vertebral column is not prolonged into the superior lobe. In all the median fms the fin-rays are supported upon a series of dagger-shaped bones, which are plunged in the flesh of the middle line of the body, and are attached to the spinous processes of the vertebrae. These are the so-called "interspinous" bones. IV. The heart consists of two chambers — an auricle and a ventricle, and the branchial artery is furnished with a bulbus arteriosus. The arterial bulb, however, is not furnished with a special coat of striated muscular fibres, is not rhythmically con- tractile, and is separated from the ventricle by no more than a single row of valves (fig. 134, A). Fig. 134. — A, Heart of the Angler (Lophius piscatoriiis). B, Arterial bulb of Bony Pike (Lefiidosteus) cut open. C, Heart of the same, viewed externally : a. Auricle ; v Ventricle ; b Arterial bulb. V. The respiratory organs consist of free, pectinated, or tufted branchiae, situated in two branchial chambers, each of which communicates internally with the pharynx by a series of clefts, and opens externally on the side of the neck by a single aper- ture (or "gill-slit"), which is protected in front by a bony gill- cover, and is also closed by a " branchiostegal membrane," sup- ported upon "branchiostegal rays." The branchiae are attached to a series of bony branchial arches, which are connected in- teriorly with the hyoid bone and superiorly with the skull ; and 360 MANUAL OF ZOOLOGY. the water required in respiration is taken in at the mouth by a process analogous to swallowing. VI. The nasal sacs never communicate posteriorly with the cavity of the pharynx. The subdivisions of the osseous fishes are so numerous, and they contain so many families, that it will be sufficient to run over the more important sub-orders, and to mention the more familiar examples of each. SUB-ORDER A. MALACOPTERI, Owen (= Physostomata, Miil- ler). — This sub-order is defined by usually possessing a com- plete set of fins, supported by rays, all of which are " soft " or many-jointed, with the occasional exception of the first rays in the dorsal and pectoral fins. A swim-bladder is always present, and always communicates with the oesophagus by means of a duct, which is the homologue of the windpipe. The skin is rarely naked, and is mostly furnished with cycloid scales ; but in some cases ganoid plates are present. This sub-order is one of great importance, as comprising many well-known and useful fishes. It is divided into two groups, according as ventral fins are present or not. In the first group — Apoda — there are no ventral fins ; and the most familiar examples are the common Eels of our ' own country. More remarkable, however, than the ordinary Eels is the Gymnotus elcctricus, or great Electric Eel, which inhabits the marshy waters of those wonderful South American plains, the so-called " Llanos." This extraordinary fish (fig. 13.5) is from Fig. 135. — Electric Eel (Gymnotus electricus). five to six feet in length, and the discharge of its electrical organs is sufficiently powerful to kill even large animals. The following striking account is given by Humboldt of the manner in which the Gymnoti are captured by the Indians : — " A number of horses and mules are driven into a swamp which is closely surrounded by Indians, until the unusual disturbance excites the daring fish to venture an attack. Serpent-like, TELEOSTEI. 361 they are seen swimming along the surface of the water, striving cunningly to glide under the bellies of the horses. By the force of their invisible blows numbers of the poor animals are suddenly prostrated ; others, snorting and panting, their manes erect, their eyes wildly flashing terror, rush madly from the raging storm ; but the Indians, armed with long bamboo staves, drive them back into the midst of the pool. " By degrees the fury of this unequal contest begins to slacken. Like clouds which have discharged their electricity, the wearied eels disperse. They require long rest and nourish- ing food, to repair the galvanic force which they have so lavishly expended. Their shocks gradually become weaker and weaker. Terrified by the noise of the trampling horses, they timidly approach the banks of the morass, where they are wounded by harpoons, and drawn on shore by non-conducting pieces of dry wo6d. " Such is the remarkable contest between horses and fish. That which constitutes the invisible but living weapon of these inhabitants of the waters — that which, awakened by the con- tact of moist and dissimilar particles, circulates through all the organs of animals and plants — that which, flashing amid the roar of thunder, illuminates the wide canopy of heaven — which binds iron to iron, and directs the silent recurring course of the magnetic needle — all, like the refracted rays of light, flow from one common source, and all blend together into one eternal all-pervading power." The second group of the Malacopteri is that of the Abdomi- nalia, in which there are ventral fins, and these are abdominal in position. Space will not permit of more here than merely mentioning that in this section are contained amongst others the well-known and important groups of the Clupeidce (Herring tribe), the Pikes (Esoridce), the Carps (Cyprinidce), the Sternop- tixituz, and the Salmonidcs^ comprising the various species of Salmon and Trout. Also belonging to this group are the Sheat-fishes (Sihiridce), which are chiefly noticeable because they are amongst the small number of living fishes possessed of structures of the same nature as the fossil spines known as " ichthyodorulites." The structure in question consists of the first ray of the pectoral fins, which is largely developed and constitutes a formidable spine, which the animal can erect and depress at pleasure. Unlike the old "ichthyodorulites," how- ever, the spines of the Siluridce have their bases modified for articulation with another bone, and they are not simply hollow and implanted in the flesh. The " Siluroids " are also remark- able for their resemblance to certain of the extinct Ganoid 362 MANUAL OF ZOOLOGY. fishes (e. g., PtericMhys, Coccosteus, &c.), caused by the fact that the head is protected with an exoskeleton of dermal bones. SUB-ORDER B. ANACANTHINI. — This sub-order is distin- guished by the fact that the fins are entirely supported by " soft " rays, and never possess " spiny" rays ; whilst the ven- tral fins are either wanting, or, if present, are placed under the throat, beneath or in advance of the pectorals, and supported by the pectoral arch. The swim-bladder may be wanting, but when present it does not communicate with the oesophagus by a duct. As in the preceding order, the Anacanthini are divided into two groups, distinguished by the presence or absence of the ventral fins. In the first of these groups (Apoda) are only a few fishes, of which one of the most familiar examples is the little Sand-eel (Ammodytes lancea), which occurs on all our coasts. In the second group (Sub-brachiata) in which ventral fins exist, are the two important families of the Gadida and Pleuronectidce. The Gadidcz or Cod family, comprising the Haddock, Whiting, Ling, and Cod itself, is of great value to man, most of its members being largely consumed as food. In the Pleuroncctida or Flat-fishes are comprised the Sole, Plaice, Turbot, Halibut, Brill and others, in all of which there is a very curious modification in the form of the body. The body, namely, in all the Flat-fishes (fig. 136) is very much compressed Fig. 136. — Pleuronectidse. Rhombus punctate. Natural size (after Gosse). from side to side, and is bordered by long dorsal and anal fins. The bones of the head are twisted in such a manner that the two eyes are both brought to one side of the body. The fish usually keeps this side uppermost and is dark-coloured on this aspect, whilst the opposite side, on which it rests, is white. From this habit of the Flat-fishes of resting upon one flat sur- TELEOSTEI. 363 face, the sides are often looked upon as the dorsal and ventral surfaces of the body. This, however, is erroneous, as they are shown by the position of the paired fins to be truly the lateral surfaces of the body. SUB-ORDER C. ACANTHOPTERI. — This sub-order is charac- terised by the fact that one or more of the first rays in the fins are in the form of true, unjointed, inflexible, "spiny" rays. The exoskeleton consists, as a rule, of ctenoid scales. The ventral fins are generally beneath or in advance of the pectorals, and the duct of the swim-bladder is invariably obliterated. This sub-order comprises two families : — a. The Pharyngognathi, in which the inferior pharyngeal bones are anchylosed so as to form a single bone, which is usually armed with teeth. The family is not of much import- ance, the only familiar fishes belonging to it being the "Wrasses" (Cyclolabrida). b. The Acanthopteri veri, characterised by having always spiny rays in the first dorsal fin, and usually in the first rays of the other fins, whilst the inferior pharyngeal bones are never anchylosed into a single mass. This family includes many subordinate groups, and may be regarded as, on the whole, the most typical division of the Teleostean Fishes. It will not be necessary, however, to do more than mention as amongst the more important fishes contained in it, the Perch family (Percidce), the Mullets (Mugilidcz), the Mackerel family (Scom- beridcE), the Gurnards (Sdcrogenid InncrQ wirh driven by (/) the pulmonary artery to mixeO- DlOOQ- the lungs, and by (o) the aorta to the purely venous, and the body with purely arterial blood — as is the case with the higher Vertebrata. In the Crocodilia, as before said, the partition between the ventricles is a complete one, and consequently this mixture of the arterial and venous blood cannot take place within the heart itself. In these Reptiles, however, a direct communication exists between the pulmonary artery and aorta (the right and left aortas) by the so-called " foramen Panizzae," close to the point where these vessels spring respectively from the right and left ventricle. In these Reptiles, therefore, the same mixture of arterial blood with DIVISIONS OF REPTILES. 397 venous takes place as in the lower Reptilia, though probably not to so complete an extent. It is this peculiarity of the circulation in all Reptiles which conditions their low tempera- ture, slow respiration, and generally sluggish vital actions. The lungs in all Reptiles, except the Crocodiles, are less completely cellular than in the Birds and Mammals, and they often attain a very great size. In no Reptile is the cavity of the thorax shut off from that of the abdomen by a complete muscular partition or " diaphragm ; " though traces of this structure are found in the Crocodiles. The lungs, therefore, often extend along the whole length of the thoracico-abdominal cavity. In no case are the lungs connected with air-receptacles situated in different parts of the body; and not uncommonly there is only a single active lung, the other being rudimentary or completely atrophied (Ophidia). Lastly, all Reptiles are essentially oviparous, but in some cases the eggs are retained within the body till the young are ready to be excluded, and the animals are then ovo-viviparous. The egg-shell is usually parchment-like, but sometimes contains more or less calcareous matter. CHAPTER LXIII. DIVISIONS OF REPTILES. CHELONIA AND OPHIDIA. THE class Reptilia is divided into the following nine orders, of which the first four are represented by living forms, whilst the remaining five are extinct : — i. Chelonia (Tortoises and Turtles). 2. Ophidia (Snakes). 3. Lacertilia (Lizards). 4. Crocodilia (Crocodiles and Alligators). 5. Ichthyopterygia. 6. Sauropterygia. Recent. Anomodontia. Pterosauria. Deinosauria. Extinct. ORDER I. CHELONIA. — The first order of living Reptiles is that of the Chelonia, comprising the Tortoises and Turtles, and 398 MANUAL OF ZOOLOGY. distinguished by the following characters : — There is an osseous exoskeleton which is combined with the endoskeleton to form a kind of bony case or box in which the body of the animal is enclosed, and which is covered by a leathery skin, or, more usually, by horny epidermic plates. The dorsal vertebrae are immovably connected together, and are devoid of transverse processes. The ribs are greatly expanded (fig. 155, r), and are united to one another by sutures, so that the walls of the thoracic cavity are immovable. All the bones of the skull except the lower jaw and the hyoid bone are immovably united together. There are no teeth, and the jaws are encased in horn so as to form a kind of beak. The heart is three-chambered, the ventricular septum being imperfect. There is a large uri- narylbladder, and the anal aperture is longitudinal or circular. Of these characters of the Chelonia, the most important and distinctive are the nature of the jaws, and the structure of the exoskeleton and skeleton. As regards the first of these points, the lower jaw in the adult appears to consist of a single piece, its complex character being masked by anchylosis! The sepa- rate pieces which really compose each ramus of the jaw are immovably anchylosed together, and the two rami are also united in front by a true bony union. There are also no teeth, and the edges of the jaws are simply sheathed in horn, constituting a sharp beak. As regards the second of these points, the bony case in which the body of a Chelonian is enclosed consists essentially of two pieces, a superior or dorsal piece, generally convex, called the "carapace," and an in- ferior or ventral piece, generally flat or concave, called the " plastron." The carapace and plastron are firmly united along their edges, but are so excavated in front and behind as to leave apertures for the head, tail, and fore and hind limbs. The limbs and tail can almost always be withdrawn at will under the shelter of the thoracico-abdominal case formed in this way by the carapace and plastron, and the head is also generally retractile. The carapace or dorsal shield is composed of the following elements : — i. The spinous processes of the dorsal vertebra, which are much flattened out laterally and form a series of broad plates. 2. The ribs, which are also much flattened and expanded, and constitute what are known as the "costal plates" (fig. 155, r). They are generally eight in number on each side, and are commonly united throughout the whole of their lateral margins by sutures. In some cases, however, they leave marginal apertures towards their extremities, and these openings are DIVISIONS OF REPTILES. 399 simply covered by a leathery skin or by horny plates. 3. The margin of the carapace is completed by a series of bony plates, which are called the " marginal plates." These are variously Fig. 155. — Skeleton of Tortoise (Emys Europea), the plastron being removed, ca Carapace; r Ribs, greatly expanded, and united by their edges; ^ Scapular arch, placed within the carapace, and carrying the fore-limbs ; p Pelvic arch, also placed within the carapace, and carrying the hind-limbs. regarded as being dermal bones belonging to the exoskeleton, or as being endoskeletal, and as representing the ossified cartilages of the ribs (in this last case the marginal plates would correspond with what are known as the " sternal ribs " of Birds). The " plastron " or ventral shield is composed of a number of bony plates (nine in number), the nature of which is doubt- ful. By Professor Owen, the plastron is still regarded as a greatly-developed breast-bone or sternum. By Huxley and Rolleston, on the other hand, the Chelonia are regarded as being wholly without a sternum, and the bones of the plastron are looked upon as exclusively integumentary ossifications. Both the carapace and the plastron are covered by a leathery skin, or more generally by a series of horny plates (fig. 156), 40O MANUAL OF ZOOLOGY. which roughly correspond with the bony plates below, and which constitute in some species the " tortoise-shell " of com- merce. These epidermic plates, however, must on no account be confounded with the true bony box in which the animal is enclosed, and which is produced partly by the true endo- skeleton, and partly by dermal integumentary ossifications. The other points of importance as regards the endoskeleton are these : — Firstly, The dorsal vertebrae are immovably joined together, and have no transverse processes, the heads of the ribs uniting directly with the bodies of the vertebrae. Secondly, The scapular and pelvic arches, supporting the fore and hind limbs respectively (fig. 155, s and/), are placed within the carapace, so that the scapular arch is thus inside the ribs, instead of being outside, as it normally is. The scapular arch consists of the shoulder-blade or scapula, and two other bones, of which one corresponds with the acromion process of human anatomy, and the other to the coracoid process, or to the "coracoid bone" of the Birds. The clavicles, as is also the case with the Crocodilia, are absent. The order Chelonia is conveniently divided into three sec- Fig. i56.—Hawk's-bill Turtle (Chelonia imbricate^— after Bell. tions, according as the limbs are natatory, amphibious, or ter- restrial. In the first of these, the limbs are converted into most efficient swimming-paddles, all the toes being united by a common covering of integument. In this section are the well- CHELONIA. 401 known Turtles (Cheloniidce), all of which swim with great ease and power, but are comparatively helpless upon the land (fig. 156). The best-known species are the "edible" or Green Turtle (Chelonia my das) ^ the Loggerhead Turtle (Chdonia caou- anna), the Hawk's-bill Turtle ( C. imbricata\ and the Leathery Turtle (Sphargis coriacea). The Green Turtle is largely im- ported into this country as a delicacy, and occurs abundantly in various parts of the Atlantic and Indian Oceans. The Hawk's-bill Turtle is of even greater commercial importance, as the horny epidermic plates of the carapace constitute the " tortoise-shell" so largely used for ornamental purposes. The Leathery Turtle is remarkable in having the carapace covered with a leathery skin in place of the horny plates which are found in other species. In the second section of the Chelonia, in which the limbs are adapted for an amphibious life, are the Mud-turtles or Soft Tortoises (Trionyctdct\ and the Terrapenes (Emydidce). In the TrionyddcB the development of the carapace is imperfect, the ribs being expanded and united to one another only near their bases, and leaving apertures near their extremities. The entire carapace is covered by a smooth leathery skin, and the horny jaws are furnished with fleshy lips. All the Trionycidcs- inhabit fresh water and are carnivorous in their habits. One of the largest and best known is the so-called Snapping Turtle (Trionyxferox] of North America, but other species are found in Egypt and in the East Indies. The Terrapenes (Emys) have a horny beak, and have the shield covered with epider- mic plates. They are inhabitants of fresh water, and are most of them natives of America. The third section of the Chelonia comprises only the Land Tortoises (Testudinida), in which the limbs are adapted for ter- restrial progression, and the feet are furnished with short nails. The carapace is strongly convex, and is covered by horny epi- dermic plates ; the head, limbs, and tail can be completely re- tracted within the carapace. Though capable of swimming, the Tortoises are really terrestrial animals, and are strictly vegetable-feeders. The most familiar species is the Testudo Graca, which is indigenous in Spain, Italy, and Greece, but is commonly kept in this country as a domestic pet. DISTRIBUTION OF .CHELONIA IN TIME. — The earliest known traces of Chelonians occur in the Permian Rocks, in the lower portion, that is, of the New Red Sandstone of older geologists. These traces, however, are not wholly satisfactory, since they con- sist solely of the footprints of the animal upon the ripple-marked surfaces of the sandstone. Of this nature is the Chelichnus VOL. II. 2 C 4O2 MANUAL OF ZOOLOGY. i) described by Sir William Jardine in his classical work on the "Ichnology" of Annandale in Dumfriesshire. The ear- liest unequivocal remains of Chelonians are in the Oolitic Rocks (the Chelonia planiceps of the Portland Stone). Fossil Chdoniidce, Emydidcz, and Trionyddce occur, also, from the Upper Oolites to the present day, the Eocene period being peculiarly rich in their remains. In the Tertiary deposits of India (Sivalik Hills) there occurs a gigantic fossil Tortoise — the ColossocMys Atlas — which is believed to have been eighteen to twenty feet in length, and to have possibly survived to within the human period. ORDER II. OPHIDI^. — The second order of Reptiles is that of the Ophidia, comprising the Snakes and Serpents, and distinguished by the following characters : — The body is always more or less elongated, cylindrical, and worm-like, and whilst possessing a covering of horny scales, is always unprovided with a bony exoskeleton. The dorsal ver- tebrae are concave in front (proccelous), with rudimentary trans- verse processes. There is never any sternum, nor pectoral arch, nor fore-limbs, nor sacrum, and as a rule there are no traces of hind-limbs. Rudimentary hind-limbs, however, are occasionally present (e.g., in Python and Tortrix). There are always numerous ribs. The two halves or rami of the lower jaw are composed of several pieces, and the rami are united anteriorly by ligaments and muscles only, and not by cartilage or suture. The lower jaw further articulates with the skull by means of a quadrate bone (fig. 153, a\ which is always more or less movable, and is in turn united with the squamous por- tion of the temporal bone, which is also movable, and is not firmly united with the skull. Hooked conical teeth are always present, but they are never lodged in distinct sockets or alveoli. Functionally, they are capable of performing nothing more than merely holding the prey fast, and the Snakes are provided with no genuine masticatory apparatus. The heart has three chambers, two auricles and a ventricle, the latter imperfectly divided into two cavities by an incomplete septum. The lungs and other paired organs are mostly not bilaterally symmetrical, one of each pair being either rudimentary or absent. There is no urinary bladder, and the cloacal aperture is transverse. Of these characters of the Snakes, the most obvious and striking are to be found in the nature of the organs of locomo- tion. The front limbs, with the scapular arch and sternum, are invariably altogether absent; and the hind-limbs, if not wholly wanting, are never represented by more than a pair of rudimentary pelvic bones concealed within the muscles on each OPHIDTA. 403 side of the anal aperture, and never exhibiting any' outward evidence of their existence beyond the occasional presence of short horny claws or spurs ("calcaria"). In the entire absence, then, or rudimentary condition of the limbs, the Snakes progress by means of the ribs. These bones are always extremely nu- merous (sometimes amounting to more than three hundred pairs), and in the absence of a sternum they are, of course, ex- tremely movable. Their free extremities, in fact, are simply terminated by tapering cartilages, which are attached by mus- cular connections to the abdominal scales or " scuta " of the integument. By means of this arrangement the Serpents are enabled to progress rapidly, walking, so to speak, upon the ends of their ribs : their movements being much facilitated by the extreme mobility of the whole vertebral column, conditioned by the cup-and-ball articulation of the bodies of the vertebrae with one another. The body in the Snakes is covered with numerous scales, developed apparently in the lower layer of the epidermis, and covered by a thin, translucent, superficial pellicle, which is peri- odically cast off and renewed. On the head and along the abdomen these scales are larger than over the rest of the body, and they constitute what are known as the " scuta " or shields. The only other points in the anatomy of the Ophidia which demand special attention are the structure of the tongue, teeth, and eye. The tongue in the Snakes is probably an organ more of Fig. 157. — A, Diagram of the eye of a Serpent (after Cloquet): a Ball of the eye covered by a conjunctival sac, into which the lachrymal secretion is discharged ; b Optic nerve ; d Antocular membrane, formed by the epidermis ; e e Ring of scales surrounding the eye. B, Head of the common Viper (Pelias berus)— after Bell — showing the bifid tongue, and the poison-fangs in the upper jaw. touch than of taste. It consists of two muscular cylinders, united towards their bases, but free towards their extremities. The bifid organ, thus constituted, can be protruded and 404 MANUAL OF ZOOLOGY. retracted at will, being in constant vibration when protruded, and being in great part concealed by a sheath when retracted. As regards the eye of Serpents (fig. 157, A), the chief peculiarity lies in the manner in which it is protected exter- nally. There are no eyelids, and hence the stony unwinking stare of all snakes. In place of eyelids, the eye is surrounded by a circle of scales (e e), to the circumference of which is attached a layer of transparent epidermis, which covers the whole eye (d), and is termed the antocular membrane. This is covered internally by a thin layer of the conjunctiva, which is reflected forwards from the conjunctiva covering the ball of the eye itself. In this way a cavity or chamber is formed between the two layers of conjunctiva, and the lachrymal secretion by which the eye is moistened is received into this. The outer epidermic layer (antocular membrane) covering the ball of the eye in front, is periodically shed with the rest of the epidermis, the animal being rendered thereby blind for a few days. The pupil of the eye is round in most Snakes, but forms a vertical slit in the venomous Serpents and in the 'Boas. As regards the dental and maxillary apparatus of the Serpents, the following points require notice. Firstly, in consequence of the articulation of the lower jaw with a movable quadrate bone, which is often directed backwards, in consequence of the quadrate bone being connected with a movable squamosal bone, and in consequence of the rami of the jaw being united in front by ligaments and muscles only, the mouth in the Snakes is capable of opening to an enormous width, and the most astonishing feats in the way of swallowing can be performed. Secondly, this structure of the jaws accords exactly with the structure of the teeth, both concurring to render the Snakes wholly incapable of anything like mastica- tion, and at the same time capable of swallowing immense morsels entire. The teeth, namely, are simply fitted for seizing and holding the prey, but not in any way for dividing or chewing it. In the harmless and most typical snakes, the teeth are in the form of solid cones, which are arranged round the margins of the upper and lower jaws, a double row existing in the palate as well. Thirdly, in the venomous snakes, however, the ordinary teeth are usually wanting upon the superior maxillae, and these bones are themselves very much reduced in size. In place of the ordinary teeth, they carry the so-called poison-fangs (fig. 157, B). These are a pair of long, conical, curved fangs, one on each maxilla, which can be raised and depressed at will. Each tooth is perforated by a tube, opening by a distinct aperture at the apex of the tooth, OPHIDIA. 405 and conveying the duct of the so-called poison-gland. This is a gland, probably produced by a modification of one of the buccal salivary glands, situated behind and under the eye on each side, and secreting the fluid which renders the bite of these snakes dangerous or fatal. When the animal strikes its prey, the poison-fangs are erected, and the poison is forced through the tube which perforates each, partly by the con- tractions of the muscular walls of the gland, and partly by the muscles of the jaws. In most poisonous snakes the superior maxillae carry no other teeth except the poispn-fangs and their rudimentary successors, but in some cases there are a few teeth behind the fangs ; whilst the palatine teeth are always present, as in the harmless species. Some of the most deadly snakes, too, carry upon the upper maxillae long grooved or canaliculated fangs, which cannot be raised or depressed at will, and which have smaller solid teeth behind them. Others, again, not certainly known to be poisonous, have canaliculated fangs placed far back upon the superior maxillae, with small solid teeth in front of them. , Fourthly, in all the Serpents the teeth are anchylosed to the jaw, and are never sunk into distinct sockets or alveoli. A good classification of the Ophidia is still a desideratum, and probably, in the meanwhile, the one proposed by Dr Gray is the best. This eminent naturalist divides the snakes into the two sub-orders of the Viperina and Colubrina, the former having only two perforated poison -fangs on the superior maxillae, whilst these bones in the latter carry solid teeth, either with or without additional canaliculated fangs. The sub-order Viperina comprises the common Vipers ( Viperida), and the Rattlesnakes ( CrotaUd) uncinate processes ; c c bternal ribs. The scapular or pectoral arch consists of the shoulder-blade or scapula, the collar-bone or clavicle, and the coracoid bone, on each side. The scapula, as a rule (fig. 168, A, s s), is a simple elongated bone, not flattened out into a broad plate, and carrying no transverse ridge, or spinous process. Only a portion of the glenoid cavity for the articulation with the head of the humerus is formed by the scapula, the remainder being formed by the coracoid. The coracoid bones (fig. 168, A, k k) correspond with the coracoid processes of man, but in birds they are distinct bones and are not anchylosed with the scap- ula. The coracoid bone on each side is always the strongest of the bones forming the scapular arch. Superiorly it articu- lates with the clavicle and scapula, and forms part of the gle- noid cavity for the humerus. Inferiorly each coracoid bone articulates with the upper angle of the sternum. The position of the coracoids is more or less nearly vertical, so that they 430 MANUAL OF ZOOLOGY. form fixed points for the action of the wings in their down- ward stroke. The clavicles (fig. 168, A, c) are rarely rudimen- tary or absent, and are in some few cases separate bones. In the great majority, however, of birds, the clavicles are anchy- losed together at their anterior extremities, so as to form a single bone, somewhat V-shaped, popularly known as the "merry-thought," and technically called the "furculum." The outer extremities of the furculum articulate with the scapula and coracoid ; and the anchylosed angle is commonly united by ligament to the top of the sternum. The function of the clavicular or furcular arch is " to oppose the forces which tend to press the humeri inwards towards the mesial plane, during the downward stroke of the wing" (Owen). Consequently the clavicles are stronger, and their angle of union is more open, in proportion to the powers of flight possessed by each bird. We have next to consider the structure of the bones which compose the fore -limb or " wing " of the bird ; and as this organ is the one which chiefly conditions the pecu- liar life of the bird, it is in it that we find some of the most characteristic points of struc- ture in the whole skeleton. Though considerably modi- fied to suit its function as an organ of aerial progression, the wing of the bird is readily seen to be homologous with the arm of a man or the fore- limb of a Mammal (fig. 168, A, and fig. 169). The upper arm (brachium) is supported by a single bone, the humerus, which is short and strong, and articulates above with the arti- cular cavity formed partly by the scapula and partly by the coracoid (fig. 169, h). The humerus is succeeded distally by the fore-arm (antibrachiwn) constituted by the normal two bones, the radius and ulna (fig. 169, r, u\ of which the radius is much the smaller and more slender, and the ulna much P Fig. 169. — Fore-limb of the Jer-falcon. k Humerus; r Radius; u Ulna; t "Thumb;" -m Metacarpals, anchylosed at their extremities; pp Phalanges of fingers. CHARACTERS OF AVES. 431 the larger and stronger. The ulna and radius are followed inferiorly by the bones of the wrist or carpus; but these are reduced in number to two small bones, "so wedged in between the antibrachium and metacarpus as to limit the mo- tions of the hand to those of abduction and adduction neces- sary for the folding up and expansion of the wing ; the hand is thus fixed in a state of pronation ; all power of flexion, exten- sion, or of rotation, is removed from the wrist-joint, so that the wing strikes firmly, and with the full force of the con- traction of the depressor muscles, upon the resisting air" (Owen). One other bone of the normal carpus (namely, the " os magnum") is present, but this is anchylosed with one of the metacarpals. There are thus really three carpal bones, though only two appear to be present. The carpus is followed by the metacarpus, the condition of which agrees with that of the carpal bones. The two outermost of the normal five metacarpals are absent, and the remaining three are anchy- losed— together with the os magnum — so as to form a single bone (fig. 169, m). This bone, however, appears externally as if formed of two metacarpals united to one another at their extremities, but free in their median portion. The metacarpal bone which corresponds to the radius is always the larger of the two (as being really composed of two metacarpals), and it carries the digit which has the greatest number of phalanges. This digit corresponds with the " index" finger, and it is com- posed of two, or sometimes three, phalanges (fig. 169, /). At the proximal end of this metacarpal, at its outer side, there is generally attached a single phalanx, constituting the so-called " thumb " (fig. 169, /), which carries the " bastard-wing." The digit which is attached to the ulnar metacarpal corresponds to the' "ring finger," and never consists of more than a single phalanx (fig. 169). As regards the structure of the posterior extremity or hind- limb, the pieces which compose the innominate bones (namely, the ilium, ischium, and pubes) are always anchylosed to one another ; and the two innominate bones are also always an- chylosed, by the medium of the greatly-elongated ilia, to the sacral region of the spine. In no living bird, however, with the single exception of the Ostrich, are the innominate bones united in the middle line in front by a symphysis pubis. The stability of the pelvic arch, necessary in animals which sup- port the weight of the body on the hind-limbs alone, is amply secured in all ordinary cases by the anchylosis of the ilia with the sacrum. As in the higher Vertebrates, the lower limb (fig. 170, A) 432 MANUAL OF ZOOLOGY. consists of a femur, a tibia and fibula, a tarsus, metatarsus, and phalanges ; but some of these parts are considerably ob- scured by anchylosis. The femur or thigh-bone (fig. 170, A, /) is generally very short, comparatively speaking. The chief Fig. 170. — A, Hind-limb of the Loon (Colytttbus glacialis) — after Owen : i Innominate bone ; f Thigh-bone or femur ; / Tibia, with the proximal portion of the tarsus an- chylpsed to its lower end ; r Fibula ; m Tarso-metatarsus, consisting of the distal portion of the tarsus anchylosed with the metatarsus ; f / Phalanges of the toes. B, Tail of the Golden Eagle : s Ploughshare-bone, carrying the great tail-feathers. bone of the leg is the tibia (/), to which a thin and tapering fibula (r) is anchylosed. The upper end of the fibula, how- ever, articulates with the external condyle of the femur. The ankle-joint is placed, as in Reptiles, between the proximal and distal portions of the tarsus. The proximal portion of the tarsus is undistinguishably amalgamated with the lower end of the tibia. The distal portion of the tarsus is anchylosed with the whole of the metatarsus to constitute the most characteristic bone in the leg of the Bird — the " tarso-metatarsus " (m). In most of the long-legged birds, such as the waders, the dispro- portionate length of the leg is given by an extraordinary elon- gation of the tarso-metatarsus. CHARACTERS OF AVES. 433 The tarso-metatarsus is followed inferiorly by the digits of the foot. In most birds the foot consists of three toes directed forwards and one backwards — four toes in all. In no wild bird are there more than four toes, but often there are only three, and in the Ostrich the number is reduced to two. In all birds which have three anterior and one posterior toe, it is the posterior thumb or hallux (that is to say, the innermost digit of the hind-limb) which is directed backwards; and it invariably consists of two phalanges only. The most internal of the three toes which are directed forwards, consists of three phalanges; the next has four phalanges ; and the outermost or " little " toe is made up of Jive phalanges (fig. 170, A). This increase in an arithmetical ratio of the phalanges of the toes, in proceeding from the inner to the outer side of the foot, ob- tains in almost all birds, and enables us readily to detect which digit is suppressed, when the normal four are not all present. Variations of different kinds exist, however, in ,the number and disposition of the toes. In many birds — such as the Parrots — the outermost toe is turned backwards, so that there are two toes in front and two behind. In others, again, the outer toe is normally directed forwards, but can be turned backwards at the will of the animal. In the Swifts, on the other hand, all four toes are present, but they are all turned forwards. In many cases — especially amongst the Natatorial birds — the hallux is wholly wanting, or is rudimentary. In the Emeu, Cassowary, Bustards, and other genera, the hallux is in- variably absent, and the foot is three-toed. In the Ostrich both the hallux and the next toe (" index ") are wanting, and the foot consists simply of two toes, these being the outer toe and the one next to it. The digestive system of birds comprises the beak, tongue, gullet, stomach, intestines, and cloaca. Teeth are invariably wanting in birds, and the jaws are encased in horn, constitut- ing the bill. The form of the bill varies enormously in differ- ent birds, and it is employed for holding and tearing the prey, for prehensile purposes, for climbing, and in some birds as an organ of touch. In these last-mentioned cases the bill is more or less soft, and is supplied with filaments of the fifth nerve. In many birds, too, in which the bill is not soft, the base of the upper mandible is surrounded by a circle of naked skin, constituting what is called the " cere," and this, no doubt, serves also as a tactile organ. The tongue of birds can hardly be looked upon as an organ of taste, since it is generally cased in horn like the mandibles. It is, in fact, principally employed as an organ of 'prehension ; VOL. II. 2 E 434 MANUAL OF ZOOLOGY. but in some cases — as in the Parrots — it is soft and fleshy, and then, doubtless, is to some extent connected with the sense of taste. It is essentially composed of a prolongation of the hyoid bone (the glosso-hyal), which is sheathed in horn, and is variously serrated or fringed. Salivary glands are invariably present, but they are rarely of large size, and they have often a very simple structure. In accordance with the structure of the neck, the gullet in birds is usually of great length, and it is generally very dilatable. In the carnivorous, or Raptorial, and in the granivorous birds, the gullet (fig. 171, o] is dilated into a pouch, which is situated Fig. 171.— Digestive System of the Common Fowl (after Owen), o Gullet ; c Crop ; / Proventriculus ; g Gizzard ; sm Small intestine ; k Intestinal caeca ; / Large in- testine ; cl Cloaca. at the lower part of the neck, just in front of the merry-thought. This is what is known as the " crop " or " ingluvies " (c), and it may be either a mere dilatation of the tube of the gullet, or it may be a single or double pouch. The food is detained in the crop for a longer or shorter time, according to its nature, before it is subjected to the action of the proper digestive organs. The cesophagus, after leaving the crop, shortly opens into a second cavity, which is known as the " proventriculus " or " ventriculus succenturiatus " (/). This is the true digestive cavity, and its mucous membrane is richly supplied with gastric CHARACTERS OF AVES. 435 follicles which secrete the gastric juice. The proventriculus, however, corresponds, not with the whole stomach of the Mam- mals, but only with its cardiac portion ; and it opens into a second, muscular cavity, which corresponds to the pyloric division of the Mammalian stomach. The gizzard (g) is situ- ated below the liver, and forms in all birds an elongated sac, having two apertures above, of which one conducts into the duodenum or commencement of the small intestine, whilst the other communicates with the proventriculus. The two chief forms of gizzard are exhibited respectively by the Raptorial birds, which feed on easily - digested animal food, and the Rasores and some of the Natatores, which feed on hardly- digested grains. In the birds of Rapine the gizzard scarcely deserves the name, being nothing more than a wide membran- ous cavity with thin walls. In the granivorous birds, whose hard food requires crushing, the gizzard is enormously devel- oped ; its lining coat is formed of a thick, horny epithelium, and its walls are extremely thick and muscular. This consti- tutes a grinding apparatus, like the stones of a mill ; whilst the " crop " or cesophageal dilatation may be compared to the " hopper " of a mill, since it supplies to the gizzard " small successive quantities of food as it is wanted " (Owen). Sup- plementing the action of the muscular walls of the gizzard, and acting in the place of teeth, are the small stones or pebbles, which, as is so well known, so many of the granivorous birds are in the habit of swallowing with their food, or at other times. In fact there can be no doubt but that the gravel and pebbles swallowed by these birds is absolutely essential to ex- istence, since the gizzard, without this assistance, is unable properly to triturate the food. The intestinal canal extends from the gizzard to the cloaca, and is comparatively speaking short. The secretions of the liver and pancreas are poured into the small intestine, as in Mammals. The commencement of the large intestine is almost always furnished with two long " caeca " or blind tubes, the length of which varies a good deal in different birds (fig. 17 1, /£). They are sometimes wanting ; and their exact function is un- certain ; though they are most probably connected partly with digestion and partly with excretion. The large intestine is always very short — seldom more than a tenth part of the length of the body — and it terminates in the "cloaca" (fig. 171, cl). This is a cavity which in all birds receives the termination of the rectum, the ducts of the generative organs and the ureters ; and serves, therefore, for the expulsion of the faeces, the gen- erative products, and the urinary secretion. MANUAL OF ZOOLOGY. Respiration is effected in Birds more completely and actively than in any other class of the Vertebrata, and as the result of this, their average temperature is also higher. This extensive development of the respiratory process is conditioned by the fact that, in addition to true lungs, air is admitted into a greater or less number of the bones, and into a number of cavities — the so-called air-receptacles — which are distributed through vari- ous parts of the body. By this extensive penetration of air into various parts of the body, the aeration of the blood is effected, not only in the lungs, but also over a greater or less extent of the systemic circulation as well ; and hence in Birds this pro- cess attains its highest perfection. The cavities of the thorax and abdomen are not separated from one another by a complete partition, the diaphragm being only present in a rudimentary form. The lungs are two in num- ber, of a bright-red - colour, and spongy texture. They are confined to the back of the thorax, extend- ing along each side of the spine, from the second dorsal vertebra to the kidney. They differ from the lungs of the Mammals in not being freely suspended in a pleural membrane. The pleura, on the other hand, is reflected only over the anterior surface of the lungs. The bronchi, or primary divisions of the wind- pipe (fig. 172), diminish in size as they pass through the lung, by giving off branches, which, in turn, give off the true air-vesicles of the lung. When the bronchial tubes reach the surface of the lung, they open, by a series of dis- tinct apertures, into a series of "air-sacs." These are a series of openings of which are seen on the back of the bronchial tubes ; b b Bris- tles passed from the bronchi through ~~ the apertures on the surface of the membranOUS SaCS formed by the lung by which the bronchi communi- continuation of the Hning mem. ig by cate with the air-receptacles. brane of the bronchi, and sup- ported by reflections of the serous membrane of the thoracico- abdominal cavity. In those aquatic birds which, like the Penguin, do not enjoy the power of flight, the air-cells are CHARACTERS OF AVES. 437 restricted to the abdomen; but in most birds they are con- tinued along the sides of the neck and limbs. In some cases — as the Pelican and Gannet — air-receptacles are situated beneath almost the whole of the integument. The air-cells not only greatly reduce the specific gravity of the bird, and thus fit them for an aerial life, but also* assist in the mechanical work of respiration, and must also greatly promote the aeration of the blood. In connection with the air-receptacles, and as an extension of them, is a series of cavities occupying the interior of a greater or less number of the bones, and also containing air. In young birds these air-cavities do not exist, and the bones are filled with marrow as in the Mammals. The extent also to which the bones are " pneumatic " varies greatly in different birds. In the Penguin — which does not fly — all the bones contain marrow, and there are no air-cavities. In the large Running Birds (Cursores), such as the Ostrich, the bones of the leg, pelvis, spine, ribs, skull, and sternum are pneumatic; but the bones of the wings, with the exception of the scapular arch,, are without air - cavities, and permanently retain their marrow. All birds which fly, with the singular exception of the Woodcock, have air admitted to the humerus. In the Pelican and Gannet, all the bones of the skeleton, except the phalanges of the toes, are penetrated by air; and in the Horn- bill even these are pneumatic. The functions discharged by the air-cavities of the bones appear to be much the same as those of the air-receptacles — namely, that of diminishing the specific gravity of the body and subserving the aeration of the blood. The heart in all Birds consists of four chambers, two auricles and two ventricles. The right auricle and ventricle, constitut- ing the right side of the heart, are wholly concerned with the pulmonary circulation ; the left auricle and ventricle, forming the left side of the heart, are altogether occupied with the systemic circulation ; and no communication normally exists in adult life between the two sides of the heart. In all essen- tial details, both as regards the structure of the heart itself and the course taken by the circulating fluid, Birds agree with Mammals. The venous blood — namely, that which has circu- lated through the body — is returned by the venae cavae to the right auricle, whence it is poured into the right ventricle. The right ventricle propels it through the pulmonary artery to the lungs, where it is aerated, and becomes arterial. It is then sent back by the pulmonary veins to the left auricle, whence it is driven into the left ventricle. Finally, the left ventricle pro- MANUAL OF ZOOLOGY. pels the aerated blood to all parts of the body through the great systemic aorta. The chief difference between Birds and Reptiles as regards the course of the circulation is, that in the Birds the two sides of the heart are completely separated from one another, the blood sent to the lungs being exclusively venous, whereas that which is sent to the body is exclusively arterial. In Reptiles, on the other hand, the pulmonary and systemic circulations are connected together either in, or in the immediate neigh- bourhood of, the heart; so that mixed venous and arterial blood is propelled both through the lungs and through every part of the body. In accordance with their extended respiration and high mus- cular activity, the complete separation of the greater and lesser circulations, and the perfect structure of the heart, Birds main- tain a higher average temperature than is the case with any other class of the Vertebrata. This result is also to a consider- able extent conditioned by the non-conducting nature of the combined down and feathers which form the integumentary covering of Birds. The urinary organs of Birds consist of two elongated kid- neys and two ureters, but there is no urinary bladder. The ureters open into the cloaca, or into a small urogenital sac which communicates with the cloaca. As regards the reproductive organs, the males have two testes placed above the upper extremities of the kidneys, and their efferent ducts (vasa deferentid] open into the cloaca alongside of the ureters. A male organ (penis] may or may not be pre- sent, but there is no perfect urethra. The female bird, as a general rule, is provided with only one ovary and oviduct — that of the left side — the corresponding organs of the right side being rudimentary or absent. The oviduct is very long and tortuous, and the egg, during its passage through it, receives the albuminous covering which serves for the nutrition of the embryo, and which is known as the " white " of the egg. The lower portion of the oviduct is dilated, and the egg receives here the calcareous covering which constitutes the " shell." Finally, the oviduct debouches into the cloaca, into which the egg, when ready, is expelled. The further development of the chick is secured by the process of " incubation " or brooding, for which birds are peculiarly adapted, in consequence of the high temperature of their bodies. The development of the ovum belongs to physiology, and does not concern us here. It is sufficient to notice the means by which in many cases the chick is ultimately enabled to escape :HARA< from the egg. When development has reached a stage at which external life is possible, it is of course necessary for the chick to be liberated from the egg, the shell of which is often ex- tremely hard and resistant. To this end, in very many in- stances, the young bird is provided with a little calcareous knob on the point of the upper mandible, and by means of this it chips out an aperture through the shell. Having effected its purpose, this temporary appendage then disappears, without leaving a trace behind. The state of the young upon exclusion from the egg is very different in different cases, and in accordance with this, Birds have been divided into the two sections tff the Autophagi or Aves prcecoces, and the Heterophagi or Aves altrices. In the Autophagi the young bird is able to run about and help itself from the moment of liberation from the egg. In the Hetero- phagi the young are born in a blind and naked state, unable to feed themselves, or even to maintain unassisted the necessary vital heat. In these birds, therefore, the young require to be brooded over and fed by the parents for a longer or shorter period after exclusion from the egg. As regards their nervous system, the brain of birds is rela- tively larger, especially as regards the size of the cerebrum proper, than the brain of Reptiles. The cerebellum, though always present, consists simply of the central lobe (the " vermi- form process "), and is not provided with the lateral lobes which occur in the Mammals, or they are only present in a rudimen- tary form. The corpus callosum is absent, and the surface of the cerebral hemispheres is devoid of convolutions. As regards the organs of the senses, the eyes are always well developed, and in no bird are they ever rudimentary or absent. The chief peculiarity of the eye is that the cornea forms a segment of a much smaller sphere than does the eyeball pro- per, so that the anterior part of the eye is obtusely conical, whilst the posterior portion is spheroidal. Another peculiarity is that the form of the eye is maintained by a ring of from thirteen to twenty bony plates, which are placed in the anterior portion of the sclerotic coat. Eyelashes are almost universally absent ; but in addition to the ordinary upper and lower eye- lids, Birds possess a third membranous eyelid — the " membrana nictitans " — which is sometimes pearly-white, sometimes more or less transparent. This third eyelid is placed on the inner side of the eye, and possesses a special muscular apparatus, by which it can be drawn over the anterior surface of the eye like a curtain, moderating the intensity of the light. As to the organ of hearing, Birds possess no external ear or concha, by 440 MANUAL OF ZOOLOGY. which sounds can be collected and transmitted to the internal ear. In some birds, however, as in the Ostrich and Bustard, the external meatus auditorius is surrounded by a circle of feathers, which can be raised and depressed at will. The ex- ternal nostrils in Birds are usually placed on the sides of the upper mandible, near its base, in the form of simple perfora- tions, which sometimes communicate from side to side by the deficiency of the septum narium. In the singular Apteryx of New Zealand the nostrils are placed at the extreme end or tip of the elongated upper mandible. Sometimes the nostrils are defended by bristles, and sometimes by a scale (Rasores). Taste must be absent, or almost absent, in the great majority of birds, the tongue being nothing more than a horny sheath surrounding a process of the hyoid bone, and serving for deglu- tition or to seize the prey. In the Parrots, however, the tongue is thick and fleshy, and some perception of taste may be present. Touch or tactile sensibility, too, as already re- marked, is very poorly developed in Birds. The body is entirely, or almost entirely, covered with feathers ; the anterior limbs are converted into wings, and rendered thereby useless as organs of touch ; and the posterior limbs are covered with horny scales or feathers. The bill certainly officiates as an organ of touch, but it cannot possess any acute sensibility, as in most birds it is encased in a rigid horny sheath. In some birds, however, such as the common Duck, the texture of the bill is moderately soft, and it is richly supplied with filaments of the fifth nerve ; so that in these cases the bill doubtless con- stitutes a tolerably efficient tactile organ. The " cere," too, or the fleshy scale found at the base of the bill in some birds, is in all probability also used as a tactile organ. The last anatomical peculiarity of Birds which requires notice is the peculiar apparatus known as the " inferior larynx," by which the song of the singing birds is conditioned. "The air-passages of birds commence by a simple superior larynx^ from which a long trachea extends to the anterior aperture of the thorax, where it divides into the two bronchi, one for each lung. At the place of its division there exists in most birds a complicated mechanism of bones and cartilages, moved by appropriate muscles, and constituting the true organ of voice; this part is termed the inferior larynx" — (Owen.) The structure of the vocal apparatus is extremely complicated, and there is no necessity for entering upon it here. It is to be remembered, however, that those modifications of the voice which constitute the song of birds, are produced in a special and complex cavity placed at the point where the trachea DIVISIONS OF BIRDS. 44! livides into the two bronchi, and not in a true larynx situated at the summit of the windpipe. Lastly, the trachea of birds is always of considerable proportionate length, and it is often twisted or dilated at intervals, this structure, doubtless, having something to do with the production of vocal sounds.* Before passing on to the consideration of the divisions of Birds, a few words may be said as to the migration of birds. In temperate and cold climates comparatively few birds remain constantly in the same region in which they were hatched. Those which do so remain, are called " permanent birds " (aves manentes). Other birds, such as the Woodpeckers, wander about from place to place, without having any fixed direction. These are called "wandering birds" (aves erraticce), and their irregular movements are chiefly conditioned by the scarcity or abundance of food in any particular locality. Other birds, however, at certain seasons of the year, undertake long journeys, usually uniting for this purpose into large flocks. These birds — such as the swallows, for instance — are properly called " migratory birds " (aves migratoricz). The movements of these birds are conditioned by the necessity of having a certain mean temperature, and consequently they leave the cold regions at the approach of winter, and return again for the warmer season. CHAPTER LXVII. DIVISIONS OF BIRDS. i. GENERAL DIVISIONS OF AVES. 2. NATATORES. 3. GRALLATORES. OWING to the extreme compactness and homogeneity of the entire class Aves, conditioned mainly by their adaptation to an aerial mode of life, the subject of their classification has been one of the greatest difficulties of the systematic Zoologist. By Professor Huxley the Birds are divided into the following three orders : — i. SAURUR.E. — In this order the caudal vertebrae are numerous, and there is no ploughshare -bone. The tail is * The student desirous of fuller information as to the anatomy of Birds should consult the masterly article by Owen on "Aves" in the ' Cyclo- paedia of Anatomy and Physiology,' or the second volume of the ' Vertebrata ' of the same author, from which the preceding summary has been chiefly derived. 442 MANUAL OF ZOOLOGY. longer than the body, and the metacarpal bones are not anchy- losed together. This order includes only the single extinct bird the Archczopteryx macrura, in which the long lizard-like tail is only the most striking of several abnormalities. 2. RATIT.E. — This order comprises the Running birds, which cannot fly, such as the Ostriches, Emeus, and Cassowaries. It is characterised by the fact that the sternum has no median ridge or keel for the attachment of the great pectoral muscles. The sternum is therefore raft-like (from the Lat. rates, a raft), hence the name of the order. 3. CARINAT^E. — This comprises all the living Flying birds, and is characterised by the fact that the sternum is furnished with a prominent median ridge or keel (carina) ; hence the name of the order. This is probably the nearest approach to a strictly natural classification of Birds which has yet been proposed ; but the order Carinatcz is so disproportionately large as compared with the other two, that it would lead to considerable inconvenience if it were to be adopted here. For the purposes of the present work it will be better to adhere, with some modifications, to the classification of the Birds originally proposed by Kirby, and since sanctioned by the adoption of other distinguished naturalists. In this more generally current, but certainly artificial, arrangement, the Birds are divided into the following seven orders, founded chiefly on the habits and mode of life, and on the resulting anatomical or structural peculiarities. To these an eighth order must be added for the reception of the Mesozoic bird, the Archceopteryx, the discovery of which dates from a recent period. Before entering upon a consideration of the individual orders, it will be as well to present to the student, synoptically and in an easily-remembered form, the leading differences between these eight orders : — 1. Natatores or Swimmers. — These are characterised by the fact that the toes are united by a membrane or web ; the legs are short and are placed behind the point of equilibrium of the body. The body is closely covered with feathers, and with a thick coating of down next the skin. (Ex. Ducks, Geese, Pelicans, Gulls.) 2. Grallatores or Waders. — The Wading birds are charac- terised by the possession of long legs, which are naked or are not covered with feathers from the distal end of the tibia downwards. The toes are long, straight, and not united to one another by a membrane or web. (Ex. Curlews, Herons, Storks.) DIVISIONS OF BIRDS. 443 3. Cur sores or Runners. — The Cursorial birds have very short wings which are not used in flight, and the sternum is without a ridge or keel. The legs are exceedingly robust, and there are only two or at most three developed toes, the hind- toe or hallux being always absent or quite rudimentary. The order agrees with the Ratita of Huxley. (Ex. Ostrich, Emeu, Apteryx. ) 4. Rasores or Scratchers. — The Rasorial birds have usually strong feet with powerful blunt claws adapted for scratching, but sometimes for perching. All the four toes are present. The upper mandible is vaulted, and the nostrils are pierced in a membranous space at its base, and are covered by a cartilaginous scale. (Ex. Fowls, Game-birds, Pigeons.) 5. Scansores or Climbers. — The Climbing birds are charac- terised by the structure of the foot, in which two toes are turned backwards and two forwards, so as to give the bird unusual facilities in climbing trees. (Ex. Parrots, Toucans, Woodpeckers.) 6. Insessores or Perchers. — The Insessorial or Passerine birds are characterised by having slender and short legs, with three toes before and one behind, the two external toes generally united by a very short membrane, and the whole foot being adapted for perching. This is by far the largest order of birds, and includes all our ordinary songsters, such as the Thrushes, Linnets, Larks, &c., together with the Swallows, Humming- birds, and many others. 7. Raptores or Birds of Prey. — The Birds of Rapine are characterised by their strong, curved, sharp-edged and sharp- pointed beak, adapted for tearing animal food ; and by their robust legs armed with four toes, three in front and one behind, all furnished with long, strong, crooked claws or talons. (Ex. Eagles, Hawks, Owls.) 8. Saururce. — The metacarpal bones are not anchylosed together, and the tail is longer than the body, and consists of numerous free vertebrse, without a terminal ploughshare-bone. The only member of this order is the extinct Archceopteryx. ORDER I. NATATORES. — The order of the Natatores or Swim- mers comprises a number of birds which are as much or even more at home in the water than upon the land. In accordance with their aquatic habit of life, the Natatores have a boat- shaped body, usually with a long neck. The legs are short, and placed behind the centre of gravity of the body, this position enabling them to act admirably as paddles, at the same time that it renders the gait upon dry land more or less 444 MANUAL OF ZOOLOGY. awkward and shuffling. In all cases the toes are " webbed " or united by membrane to a greater or less extent (fig. 173, A). In many instances the membrane or web is stretched com- pletely from toe to toe, but in others the web is divided or split up between the toes, so that the toes are fringed with membranous borders, but the feet are only imperfectly webbed. As their aquatic mode of life exposes them to great reductions of temperature, the body of the Natatorial birds is closely covered with feathers and with a thick coating of down next the skin. They are, further, prevented from becoming wet in the water by the great development of the coccygeal oil-gland, by means of which the plumage is kept constantly lubricated and waterproof. They are usually polygamous, each male consorting with several females ; and the young are hatched in a condition not requiring any special assistance from the parents, being able to swim and procure food for themselves from the moment they are liberated from the egg. A Fig. 173. — Natatores. A, Foot of Cormorant (Phalacrocorax) ; B, Beak of the Bean-goose (A user segetunf), The Natatores are divided by Owen into the following four families : — JFdm. i. Brevipennate. — In this family of the swimming birds the wings are always short, and are sometimes useless as organs of flight, the tail is very short, and the legs are placed very far back, so as to render terrestrial progression very diffi- cult or awkward. The family includes the Penguins, Auks, Guillemots, Divers, and Grebes. In the Penguins (Sphenistidcz} the wings are completely rudimentary, without quills, and cov- ered with a scaly skin. They are useless, as far as flight is con- cerned, but they are employed by the bird as fins, enabling it to swim under water with great facility. The feet are webbed, and the hinder toe is rudimentary or wanting. The Pen- guins live in the seas of the southern hemisphere, on the coasts NATATORES. 445 of South Africa and South America, especially at Terra del Fuego, and in the solitary islands of the South Pacific. When on land the Penguins stand bolt upright, and as they usually stand on the shore in long lines, they are said to present a most singular appearance. In the Auks (Alcidce) the wings are better developed than in the Penguins, and they contain true quill- feathers • but they are still short as compared with the size of the body, and are of more use as fins than for flight. The great Auk or Gare-fowl (Alca impennis) is remarkable for being one of the birds which appear to have become entirely extinct within the human period, having been, in fact, destroyed by man himself. It used to abound in the arctic regions, and occasionally visited our own shores in the winter. The little Auk (Mergulus alba) occurs still in abundance in the seas of the arctic regions. Other well-known members of this group are the Razor-bill, the Puffins (Fratercula arctica], and the Guil- lemots (Una). In the Divers (Colymbidcz), comprising the true Divers and the Grebes, the power of flight is pretty well developed, but the bird still is much more active in the water, swimming or diving, than on land. The Grebes are not uncommon in our own country, and are largely killed for making muffs, collars, and other articles of winter dress. They have the membrane between the toes deeply incised. In the Divers proper the front toes are completely united by a membrane. The Nor- thern Diver or Loon (Colymbus glacialis) is a familiar example, and is found on the coasts of high northern latitudes. Fam. 2. Longipennatce. — This family of Natatores is charac- terised by the well-developed wings, the pointed, sometimes knife-like, sometimes hooked bill, and by never having the hallux united with the anterior toes by a membrane. The fol- lowing are the more important groups coming under this head : — a. Laridcz, or Gulls and Terns, having powerful wings, a free hinder toe, and the three anterior toes united by a membrane. The Gulls form an exceedingly large and widely distributed group of birds ; and the Terns or Sea-swallows are equally beautiful, if not quite so common. b. Procellarida, or Petrels, closely resembling the true Gulls, but having no hinder toe, and having the upper mandible strongly hooked. The smaller species of Petrel are well known to all sailors under the name of Storm-birds and Mother Carey's Chickens. The largest member of the group is the gigantic Albatross (Diomedea exulans), not uncommonly found far from land in both the northern and southern oceans. The 446 MANUAL OF ZOOLOGY. Albatross sometimes measures as much as fifteen feet from the tip of one wing to that of the other, and their flight is powerful in proportion. Fam. 3. Totipalmata, characterised by having the hinder toe or hallux more or less directed inwards, and united to the innermost of the anterior toes by a membrane (fig. 173, A). In • this family are the Pelicans, Cormorants, Gannets, Frigate- birds, Darters, and others. The Pelicans (Pduanida) are large birds, which subsist on fish, and are found in Europe, Asia, Africa, and the New World. They sometimes measure as much as from ten to fif- teen feet between the tips of the wings, and most of the bones are pneumatic, so that the skeleton is extremely light. The lower mandible is composed of two flexible branches which serve for the support of a large " gular " pouch, formed by the loose unfeathered skin of the neck. The fish captured by the bird are temporarily deposited in this pouch, and the parent birds feed their young out of it. In the Cormorants (Phalacrocorax) there is no pouch be- neath the lower mandible, but the skin of the throat is very lax and distensible. They are widely distributed over the world, one species being very abundant in many parts of Europe. The Gannets (Sula) have a compressed bill, the mar- gins of which are finely crenate or toothed. They occur abundantly on many parts of the coasts of northern Europe, one of the most noted of their stations being the Bass Rock at the mouth of the Firth of Forth. Another species (Sula varie- gata) is of greater importance to man, as being one of the birds from the accumulated droppings of which guano is derived. The Frigate-birds (Tachypetes) are chiefly remarkable for their extraordinary powers of flight, conditioned by their enormously long and powerful wings and long forked tail. They occur on the coasts of tropical America, and are often found at im- mense, distances from any land. The Darters (Plotus) are somewhat aberrant members of this group, characterised by their elongated necks and long pointed bills. They occur in America, Africa, and Australia, and catch fish by suddenly darting upon them from above. Fam. 4. Lamellirostres. — The last family of the Natatores is that of the Lamellirostres, including the Ducks, Geese, Swans, and Flamingos ; and characterised by the form of the beak (figs. 167, 173), which is flattened in form and covered with a soft skin. The edges of the bill are further furnished with a series of transverse plates or lamellae, which form a kind of fringe or " strainer," by means of which these birds sift the NATATORES. 447 mud in which they habitually seek their food. The bill is richly supplied with filaments of the fifth nerve, and doubtless serves as an efficient organ of touch. The feet are furnished with four toes, of which three are turned forwards, and are webbed, whilst the fourth is turned backwards, and is free. The trachea in the males is generally enlarged or twisted in its lower part, and co-operates in the production of the peculiar clanging note of most of these birds. The body is heavy, and the wings only moderately developed. The groups of the Ducks (Anatida>\ Geese (Anserina}, and Swans (Cygnid — /. e., are placed on the chest. There are no clavicles, and the digits have no more than three phalanges each. The testes are retained throughout life within the abdomen, but vesiculae seminales are present. The animal is diphyodont, the perma- nent teeth consisting of molars with flattened crowns adapted for bruising vegetable food, and incisors which are present in the young animal, at any rate. In the extinct Rhytina it does not appear that there were any incisor teeth. Fig. 192. — Sirenia. Dugong (Halicore). The only existing Sirenia are the Manatees (Manatus) and the Dugongs (Halicore), often spoken of collectively as " sea- cows," and forming the family of the Manatidce. The Manatees are characterised by the possession of numer- g g ous molar teeth (o~o), and of two small upper incisors, which are wanting in the adult. The tail-fin is oblong or oval in shape, and the anterior limbs are furnished with nails to the four outer digits. They occur on the east coast of North America, especially in the Gulf of Mexico, and another species is found on the west coast of Africa. They are generally found in considerable numbers about the mouths of rivers and estu- aries, and they appear to live entirely upon sea-weeds, aquatic plants, or the littoral vegetation. They are large awkward animals, attaining a length of from eight to ten feet as a rule, but sometimes growing to a length of nearly twenty feet. The Dugongs (Halicore, fig. 192) have -^ molar teeth in 2 2 the young condition, but only — - — when old. Inferior incis- ors are present in the young animal, but are wanting in the adult. The upper jaw carries two permanent incisors, which 504 MANUAL OF ZOOLOGY. are entirely concealed in the jaw in the females, but which increase in size in the males with the age of the animal, till they become pointed tusks. The anterior extremities are nail- less, and the tail-fin is crescentic in shape. In their general appearance and in their habits the Dugongs differ little from the Manatees, and they are often killed and eaten. They attain a length of from eight to ten, twelve, or more feet, and are found chiefly on the coasts of the Indian Ocean. The bones are remarkable for their extreme density, their texture being nearly as close as ivory. The Manatees and Dugongs, as before said, are the only living Sirenia; but besides these there is a very singular form, the Rhytina Stelleri, which is now extinct, having been exter- minated by man within a comparatively recent period. This remarkable animal was discovered about the middle of the eighteenth century in a little island (Behring's Island) off the coast of Kamschatka. Upon this island the celebrated voyager Behring was wrecked, and he found the place inhabited by these enormous animals, which were subsequently described by M. Steller, who formed one of his party. The discovery, however, was fatal to the Rhytina, for the last appears to have been seen in the year 1768. The Rhytina was an animal of great size, measuring twenty-five feet in length, and twenty feet at its greatest circumference. There can hardly be said to T y have been any true teeth, but the jaws contained — - large lamelliform fibrous structures, which officiated as teeth, and may be looked upon as molars. The epidermis was extremely thick and fibrous, and hairs appear to have been wanting. There was a crescentic tail-fin, and the anterior limbs alone were present ORDER V. CETACEA. — In this order are the Whales, Dol- phins, and Porpoises, all agreeing with the preceding in their complete adaptation to an aquatic life (figs. 195, 196). The body is completely fish-like in form ; the anterior limbs are con- verted into swimming - paddles or "flippers"; the posterior limbs are completely absent ; and there is a powerful, horizon- tally-flattened, caudal fin, sometimes accompanied by a dorsal fin as well. In all these characters the Cetacea agree with the Sirenia, except in the one last mentioned. On the other hand, the nostrils, which may be single or double, are always placed at the top of the head, constituting the so-called " blow-holes" or "spiracles"; and they are never situated at the end of a snout. The body is very sparingly furnished with hairs, or the adult may be completely hairless. The testes are retained CETACEA. 505 . throughout life within the abdomen and there are no vesiculse seminales. The teats are two in number and are placed upon the groin. The head is generally of disproportionately large size, and is never separated from the body by any distinct con- striction or neck. The lumbar region of the spine is long, and, as in the Sirenia, there is no sacrum, and the pelvis is only present in a rudimentary form. There are no clavicles, and some of the digits may possess more than three phalanges each. Lastly, the adult is either destitute of teeth or is mono- phyodont — that is to say, possesses but a single set of teeth, which are never replaced by others. When teeth are present, they are usually conical and numerous, and they are always of one kind only. The Cetacea may be divided into the three families of the Balanida or Whalebone Whales, the Delphinida or Dolphins and Porpoises, and the Catodontidce. or Sperm Whales. Of these, the Balcznidce are often spoken of as the " toothless " Whales, whilst the other two families are called the " toothed " Whales (Odontoceti). Fig. 193. — Skull of the Right Whale Bal&na mysticetus) — after Owen. Fam. i. Balcznidcz. — The J3al — 7 molars. 6 — o Three species of Tapir are known, of which the most familiar is the American Tapir (T. Americanus\ which inhabits the vast forests of South America. It is a large animal, something like a pig in shape, but brownish black in colour. It is nocturnal in its habits, and is strictly phytophagous. The proboscis is employed in conveying the food to the mouth, and the nostrils are placed at its extremity. It attains altogether a total length UNGULATA. 5 15 of from five to six feet. Another species, with longer hair (T. villosus), inhabits the Andes, and a still larger species (T. Ma- layanus] is found in Sumatra and Malacca. Nearly allied to the Tapirs is the fossil genus Palczotherium, found in the Eocene Rocks of France and other countries. Many species of the genus are known, all seeming to have possessed a short proboscis like that of the Tapirs. All the feet, however, were tridactylous. Fam. 3. Solidungula or Equida. — This family comprises the Horses, Asses, and Zebras, characterised by the fact that the feet have only a single perfect toe each, enclosed in a single broad hoof, without supplementary hoofs (fig. 197, A). There is a discontinuous series of teeth in each jaw ; and in the males, canines are present, but these are wanting in the females. The dental formula is — / 2=3. c ^1 ; pm 3=3 ; m 3-3 = 40. 3—3 i— i 3—3 3—3 The skin is covered with hair, and the neck is furnished with a mane. The family Equidcz is divided by Dr Gray into two sections or genera: Equus, comprising the Horse; and Asinus, com- prising the Asses and Zebras. The genus Equus is distinguished by the fact that the animal is not banded, and has no dorsal line, both the fore and hind legs have warts, and the tail is hairy throughout. The genus appears to contain no more than one well-marked species, as far as living forms are concerned — namely, the Equus caballus. From this single species appear to have descended all the in- numerable varieties of horses which are employed by man. The native country of the horse appears to have been Central Asia, but all the known wild individuals at the present day appear to be descendants of domestic breeds. The genus Asinus is characterised by the fact that there is always a distinct dorsal line, and the body is more or less banded, the fore-legs alone have warts, and the tail has a tuft of long hairs at its extremity. The Ass is probably a native of Asia (where the wild Ass is at present a native), and there ap- pears to be little doubt but that the common Ass is merely the domesticated form of the wild Ass (Equus onager]. The striped members of this section are known as Zebras and Quaggas, and are natives of the southern parts of Africa. SECTION B. ARTIODACTYLA. — In this section of the Ungu- lates the number of the toes is even — either two or four — and the third toe in each foot forms a symmetrical pair with the 5l6 MANUAL OF ZOOLOGY. fourth (fig. 197, B, C). The dorso-lumbar vertebrae are nineteen in number, and there is no third trochanter on the femur. If true horns are present, these are always in pairs, and are sup- ported by a bony horn-core. The antlers of the Deer are also paired, but they are not to be regarded as true horns. The stomach is always more or less complex, or is divided into se- parate compartments, and the caecum is comparatively small and simple. The section Artiodactyla comprises the Hippopotamus, the Pigs, and the whole group of the Ruminants, including Oxen, Sheep, Goats, Antelopes, Camels, Llamas, Giraffes, Deer, &c. Besides these there is an extensive series of fossil forms com- mencing in the Eocene or Lower Tertiary period, and in many respects filling up the gaps between the living forms. OMNIVORA. 1. HippopotamidcR. — This group contains only the single genus Hippopotamus, characterised by the massive heavy body, the short blunt muzzle, the large head, and the presence of 2~~^2 teeth of three kinds in both jaws. The incisors are > the 2 2 canines extremely large, - — , and the molars —^ or •? — -^ with crowns adapted for grinding vegetable substances. The feet are massive, and are terminated by four hoofed toes each. The eyes and ears are small, and the skin is extremely thick, and is furnished with few hairs. The tail is very short. Several extinct species of Hippopotamus are known, but there is only one well-established living form, the Hippopotamus am- phibius, and this is confined to the African continent. It is an enormously bulky and unwieldy animal, reaching a length of eleven or twelve feet. It is nocturnal in its habits, living upon grass and small shrubs, and it swims and dives with great facility. It is found in tolerable abundance in the rivers of Abyssinia, and occurs plentifully in South Africa. Another supposed species (H. Liberiensis) occurs on the west coast of Africa, but there is some doubt as to the specific distinct- ness of this. 2. Suida. — The group of the Suida, comprising the Pigs, Hogs, and Peccaries, is very closely allied to the preceding ; but the feet have only two functional toes, the other two toes being placed at some elevation above the ground, and being rudimentary. All the three kinds of teeth are present, but they vary a good deal. The canines always are very large, and in UNGULATA. 517 the males they usually constitute formidable tusks projecting from the sides of the mouth. The molars vary from three to ^ *y tj >y seven on each side of the mouth ( -^- or -—-). The stom- «$ ^ O I I ach is mostly slightly divided, and is not nearly so complex as in the Ruminants. The snout is truncated and cylindrical, and is capable of considerable movement. The skin is more or less abundantly covered with hair, and the tail is very short, or represented only by a tubercle. Of the true Swine, the best known and most important is the Wild Boar (Sus scrofa), from which it is probable that all our domestic varieties of swine have sprung. The Wild Boar formerly inhabited this country, and is still abundant in many of the forests of Europe. It is often hunted, and the size and sharpness of its canines render it a tolerably formidable adver- sary, as is also its congener, the Indian Hog (Sus Indicus). Another curious form, closely related to the Wild Boar, is the Babyroussa (Sus Babyrussa), which inhabits the Malayan Pen- insula, and some of the islands of the Indian Archipelago. It is remarkable for the great size and backward curvature of the upper canines. The African Wart-hogs, forming the genus Phacoch&rus, are distinguished by having a fleshy wart under each eye. They inhabit Abyssinia, the Guinea coast, and other parts of Africa. The American Peccaries (Dicotyles) represent the Swine of the Old World. They are singular for having only three toes on the hind-feet, the outer of the two supplemental hoofs being wanting. They are exclusively confined to America, and the commonest species is the Collared Peccary (Dicotyks torquatiis}. They are not at all unlike small pigs either in their appearance or in their habits, and they are gregarious, generally occurring in small flocks. Forming a kind of transition between the Swine and the true Ruminants, is the extinct group of the Anoplotheridce, from the Lower Tertiary Rocks. The Anoplotheria were slender in form, with long tails, and feet terminated by two hoofed toes each, sometimes with small accessory hoofs. The dentition consisted of six incisors in each jaw, small canines not larger than the incisors, and seven molars on each side, there being no interval or diastema between the molars and the canines. RUMINANTIA. The last section of the Artiodactyle Ungulates is the great and natural group of the Ruminantia^ or Ruminant animals. 5l8 MANUAL OF ZOOLOGY. This section comprises the Oxen, Sheep, Antelopes, Giraffes, Deer, Camels, &c., and is distinguished by the following char- acters : — The foot is what is called " cloven," consisting of a symmet- rical pair of toes encased in hoofs, and looking as if produced by the splitting into two equal parts of a single hoof. In addi- tion to these functional toes, there are usually two smaller sup- plementary hoofs placed at the back of the foot. The meta- carpal bones of the two functional toes of the fore-limb, and the metatarsal bones of the same toes of the hind-limb, coalesce to form a single bone, known as the "canon-bone." The stomach is complex, and is divided into several compartments, this being in accordance with their mode of eating. They all, namely, ruminate or " chew the cud" — that is to say, they first swallow their food in an unmasticated or partially-masticated condition, and then bring it up again, after a longer or shorter time, in order to chew it thoroughly. This process of rumination is so characteristic of this group, that it will be necessary to describe the structure of the stomach, as showing the mechanism by which this singular process is effected. The stomach (fig. 199) is divided into four compartments, which are usually so distinct from one another that they have generally been spoken of as so many separate stomachs. The gullet opens at a point situated between the first and second of these cavities or " stomachs." Of these the largest lies on the left side, and is called the " rumen" or "paunch" (fig. 199, r.) This is a cavity of very large capacity, having its interior furnished with numerous hard papillae or warts. It is the chamber into which the food is first received when it is swallowed, and here it is moistened and allowed to soak for some time. The second stomach, placed to the right of the paunch, is much smaller, and is known as the "reticulum" or "honeycomb -bag" (ti). Its inner surface is reticulated, or is divided by ridges into a number of hexagonal or many-sided cells, somewhat resem- bling the cells of a honeycomb. The reticulum is small and globular, and it receives the food after it has lain a sufficient time in the paunch. The function of the reticulum is to com- press the partially-masticated food into little balls or pellets, which are then returned to the mouth by a reversed action cf the muscles of the oesophagus. After having been thoroughly chewed and prepared for digestion, the food is swallowed for the second time. On this occasion, however, the triturated food passes on into the third cavity (/), which is variously known as the "psalterium," "omasum," or (Scoff ice) the "many- UNGULATA. 519 plies." The vernacular and the first of these technical names both refer to the fact that the inner lining of this cavity is thrown into a number of longitudinal folds, which are so close as to resemble the leaves of a book. The psalterium opens by a wide aperture into the fourth and last cavity, the " abo- masum" (a), both appearing to be divisions of the pyloric Fig. 199. — Stomach of a Sheep, o Gullet; r Rumen or Paunch ; h Honeycomb-bag or Reticulum; p Manyplies or Psalterium; a. Fourth Stomach or Abomasum. portion of the stomach. The mucous membrane of the abo- masum is thrown into a few longitudinal folds, and it secretes the true acid gastric juice. It terminates, of course, in the commencement of the small intestine — i.e., the duodenum. The intestinal canal of Ruminants, as in most animals which live exclusively upon a vegetable diet, is of great relative length. The dentition of the Ruminants presents peculiarities al- most as great and as distinctive as those to be derived from the digestive system. In the typical Ruminants (e.g-, Oxen, Sheep, Antelopes), there are no incisor teeth in the upper jaw, their place being taken by a callous pad of hardened gum, against which the lower incisors impinge (fig. 200). There are also no upper canine teeth, and the only teeth in the upper jaw are six molars on each side. In the front of the lower jaw is a continuous and uninterrupted series of eight teeth, of which the central six are incisors, and the two outer ones are regarded by Owen as being canines. Upon this view, canine teeth are present in the lower jaw of the typical Ruminants, and they are only remarkable for being placed in the same series as the incisors, which they altogether resemble in shape, size, and direction. Behind this continuous series of eight teeth in the lower jaw there is a vacant space, which is followed behind by six molars on each side. 520 MANUAL OF ZOOLOGY. The dental formula, then, for a typical Ruminant animal is — The departures from this typical formula occur in the Camelidce and in some of the Deer. Most of the Deer conform in their Fig, 200. — Skull of a hornless Sheep (after Owen), i Incisors ; c Canines ; in Molars and praemolars. dentition to the above formula, but a few forms (e.g., the Musk- deer) have canine teeth in the upper jaw. These upper canines, however, are mostly confined to the males ; and if they occur in the females, they are of a small size. The denti- tion of the Camelidce (Camels and Llamas) is still more aber- rant; there being two upper incisors and upper canines as well. The lower canines also are more pointed and stand more erect than the lower incisors, so that they are easily recognisable. The group of the Ruminantia includes the families of the Camelidce (Camels and Llamas), the Moschidce (Musk-deer), the Cervidce (Deer), the Camelopardalidce (Giraffe), and the Cavicorhia (Oxen, Sheep, Goats, Antelopes). a. Camelidce. — The Camels and Llamas constitute in many respects an aberrant group of the Ruminantia, especially in their dentition, the peculiarities of which have been spoken of above, and need not be repeated here. In their feet, too, the Camelidce are peculiar. The feet are long and terminate in UNGULATA. $21 only two toes, which are covered by an imperfect nail-like hoof, covering no more than the upper surface of each toe. The two hinder supplementary toes, which are generally pre- sent in the Ruminants, are here altogether wanting ; and the soles of the feet are covered by a callous horny integument upon which the animal walks. The head in all the Camelida is destitute of horns, and the nostrils can be closed at the will of the animal. The true Camels are peculiar to Asia and Africa, and two species are known, distinguished from one another by the possession of a double or single adipose hump on the back. The African or Arabian Camel ( Came/us Dromedarius) is often called the Dromedary, and has only one hump on its back. The two toes are united together by the callous sole ; and the chest, shoulders, and knees are furnished with callous pads, upon which they rest when they lie down. The hump is almost entirely composed of fat, and appears to act as a kind of reserve supply of food, as it is noticed to diminish much in size upon long journeys. The Camel can likewise support a very prolonged deprivation of water, as the paunch is furnished with large cells, which the animal fills when it has access to water, and then makes use of subsequently as occasion may require. The structure of the Camel adapts it admirably for locomotion in the sandy deserts of Arabia and Africa ; and as it is very docile and good-tempered, it is almost exclusively employed as a beast of burden in the countries in which it occurs. The Bactrian Camel ( C. Bactrianus) is distinguished by the possession of two humps ; but in other respects it does not differ from the Dromedary. The two species are said to breed together, and the hybrid offspring is stated to be occa- sionally fertile. The place of the Camels is taken in the New World by the Llama ; and Alpaca, with two other nearly-allied forms. These animals form the genus Auchenia^ and are in many respects similar to the true Camels. They are distin- guished, however, by having no hump upon the back, and by the fact that the sole of the foot is destitute of a callous pad. The Llamas are chiefly found in Peru and Chili, and consider- able doubt exists as to the number of species. They live in flocks in mountainous regions, and are much smaller than the Camels in size. The true Llama is kept as a domesticated animal, and used as a beast of burden. The Alpaca is still smaller than the Llama, and is not very unlike a sheep, having a long woolly coat. It is partially domesticated, and the wool is largely imported into Europe. 522 MANUAL OF ZOOLOGY. b. Moschida. — The second group is that of the Musk-deer, characterised by the total absence of horns in both sexes, and by the presence of canines in both jaws, those in the upper jaw being in the form of tusks in the males, but being much smaller in the females. The true Musk-deer (Moschns moschiferus) is an elegant little animal, which inhabits the elevated plains of central Asia. It is remarkable for the fact that the male has a glan- dular sac on the abdomen, by which the well-known perfume, musk, is secreted. c. Cervidce. — This family is of much greater importance than that of the Moschidce, including as it does all the true Deer. They are distinguished from the other Ruminants chiefly by the nature of the horns. With the single exception of the Reindeer, these appendages are confined to the males amongst the Cervidtz, and do not occur in the females. They do not consist, as in the succeeding group, of a hollow sheath of horn surrounding a central bony core, nor are they permanently re- tained by the animal. On the other hand, the horns, or, as they are more properly called, the antlers, of the Cervidce are deciduous, and are solid. They are bony throughout, and are usually more or less branched, and they are annually shed and annually reproduced at the breeding season. They increase in size and in the number of branches every time they are reproduced, until in the old males they may attain an enormous size. The antlers are carried upon the frontal bone, and are produced by a process not at all unlike that by which injuries of osseous structures are made good in man. At first the antlers are covered with a sensitive hairy skin ; but as develop- ment proceeds, the vessels of the skin are gradually obliter- ated, and the skin dies and peels off. In all the Deer there is a sebaceous gland, called the "lachrymal sinus," or " larmier," which is placed beneath each eye, and secretes a strongly- smelling waxy substance. The Cervidcs are very generally distributed, but no member of the group has hitherto been discovered in either Australia or South Africa, their place in the latter continent seeming to be taken by the nearly-allied Antelopes (distinguished by their hollow horns). Very many species of Cervidcs are known, and it is not pos- sible to allude to more than two or three of the more familiar and important forms. Three species occur in Britain — namely, the Roebuck, Red -deer, and Fallow-deer, the last being a doubtful native. The Roebuck (Capreolus caprcea) was once very generally distributed over Britain, but is almost confined UNGULATA. 523 to the wilder parts of Scotland at the present day. It is of small size, and the horns are without brow-tynes, and are of small size, with three terminal branches. The Red-deer, or Stag (Cervus elephus] is a much larger species, with well- developed spreading antlers. It is still found in the Lake- district and in Scotland, but it is gradually in process of exter- mination. The Red-deer of this country is represented in NortrriAmerica by a still larger species, known as the Wapiti (Cervus Canadensis). The third British species is the Fallow-deer (Dama platyceros), characterised by the fact that the antlers are palmated — that is, dilated towards their extremities. It is a doubtful native, and is never found in a wild state at the present day. Allied to the Fallow-deer is a gigantic extinct species, the Megaceros Hibernicus, which inhabited Ireland, the Isle of Man, Scotland, and probably the greater part of Europe, up to a comparatively modern date, probably having survived into the human period. It is often, but incorrectly, spoken of as the Irish " Elk," but it is really a genuine Stag. The animal was of very great size, and was furnished with enormous spreading and palmate antlers, which measure from ten to twelve feet between the tips. Of all the Deer, the largest living form is the true Elk (Alces palmatus\ which is generally distributed over the northern parts of Europe, Asia, and America, being often spoken of as the Moose. The antlers in the Elk are of very large size, and are very broad, terminating in a series of points along their outer edges. The only completely domesticated member of the Cervidce is the Reindeer (Cervus tarandus], which is remarkable for the fact that the female is furnished with antlers similar to, but smaller than, those of the males. At the present day the Rein- deer is exclusively confined to the extreme north of Europe and Asia, abounding especially in Lapland. Remains, however, of the Reindeer are known to occur over the greater part of Europe, extending as far south, at any rate, as the Alps, and occurring also in Britain. From this fact, taken along with many others, the existence of an extremely cold climate over the greater part of Europe at a comparatively recent period may be safely inferred. The Reindeer lives chiefly upon moss and a pecu- liar kind of lichen (Lichen rangiferind), and they are extensively used by the Laplanders both as beasts of burden and as sup- plying food. d. Camelopardalidcz. — This family includes only a single living animal — the Camelopardalis Giraffa, or Giraffe — some- times called the Camelopard, from the fact that the skin is 524 MANUAL OF ZOOLOGY. spotted like that of the Leopard, whilst the neck is long, and gives it some distant resemblance to a Camel. There are no upper canines in the Giraffe, and both sexes possess two small frontal horns, which, however, are persistent, and remain per- manently covered by a hairy skin. The neck is of extraordi- nary length, but, nevertheless, consists of no more than the nor- mal seven cervical vertebrae. The fore-legs appear to be much longer than the hind-legs, and all are terminated by two toes each, the supplementary toes being altogether wanting. The tongue is very long and movable, and is employed in stripping leaves off the trees. The Giraffe is the largest of all the Ruminants, measuring as much as from fifteen to eighteen feet in height. It is a harmless and inoffensive animal, but defends itself very effectually, if attacked, by kicking. It is found in Nubia, Abyssinia, and the Cape of Good Hope. Remains of gigantic Ruminants allied to the Giraffe have been found in France and Greece (Helladotherium) ; but the Sivatherium, sometimes referred to this family, appears to have been more nearly allied to the true Antelopes. e. Cavicornia. — The last family of the Ruminants is that of the Cavicornia or Bovidcz, comprising the Oxen, Sheep, Goats, and Antelopes. This family includes the most typical Rumi- nants, and those of most importance to man. The upper jaw in all the Cavicornia is wholly destitute of incisors and canines, the place of which is taken by the hardened gum, against which the lower incisors bite. There are six incisors and two canines in the lower jaw, placed in a continuous series, and the molars are separated by a wide gap from the canines. There are six molars on each side of each jaw. Both sexes have horns, or the males only may be horned, but in either case these appendages are very different to the " antlers " of the Cervidcz. The horns, namely, are persistent, instead of being deciduous, and each consists of a bony process of the frontal bone — or "horn-core" — covered by a sheath of horn. The feet are cleft, but are furnished with accessory hoofs placed on the back of the foot. The Cavicornia comprise the three families of the Antilopidcz, Ovidcz, and Bovidcz. The Antelopes form an extremely large section, with very many species. They are characterised by their slender deer-like form, their long and slender legs, and their simple cylindrical or twisted horns, which are usually confined to the males, but sometimes occur in the females as well. The Antelopes must on no account be confounded with the true Deer, to which they present many points of similarity. Th e structure of the horns, however, is quite sufficient to dis- UNGULATA. 525 tinguish them. The Antelopes are especially numerous, both in individuals and in species, in Africa, in which country they appear to take the place of the true Deer (only one species of Deer being indigenous to Africa). Amongst the better-known African species of Antelopes are the Springbok, Hartebeest, Gnu, Eland, and Gazelle. The only European Antelope is the Chamois (Rupicapra tragus), which inhabits the Alps and other mountain-ranges of southern Europe. The Sheep and Goats (Ovidce) have mostly horns in both sexes, and the horns are generally curved, compressed, and turned more or less backwards. The body is heavier, and the legs shorter and stouter than in the true Antelopes. In the true Goats (Capra) both sexes have horns, and there are no lachrymal sinuses. The throat is furnished with long hair, forming a beard, and this appendage is usually present in both sexes, though sometimes in the males only. The goats live in herds, usually in mountainous and rugged districts. The do- mestic Goat ( Capra hircus) is generally believed to be a descen- dant of a species which occurs in a wild state in Persia and in the Caucasus (the " Paseng," or Capra tzgagrus). The true sheep (Ovis) are destitute of a beard, and the horns are gener- ally twisted into a spiral. Horns may be present in both sexes, or in the males only. Lachrymal sinuses are almost in- variably present. Numerous varieties of the domestic Sheep (Ovis anes)a.re known, but it is not certainly known from what wild species these were originally derived. The Merino Sheep (a Spanish breed) and the Thibet Sheep are particularly cele- brated for their long and fine wool. With the exception of one species (the Big-horn, Ovis montano), all the Sheep appear to be originally natives of the Old World. The true Oxen (Bovidce) are distinguished by having simply rounded horns, which are not twisted in a spiral manner. There are no lachrymal sinuses. Most of the Oxen admit of being more or less completely domesticated, and some of them are amongst the most useful of animals, both as beasts of burden and as supplying food. The parent-stock of our nu- merous breeds of cattle is not known with absolute certainty ; the nearest approach to British Wild Cattle being a celebrated breed which is still preserved in one or two places. These " Chillingham Cattle" are a fine wild breed, which at one time doubtless existed over a considerable part of Britain. They are pure white, with a black muzzle, the horns white, tipped with black. Another large Ox, which formerly existed in Brit- ain, and abounded over the whole of Europe, is the Aurochs or Lithuanian Bison (Bos bison}. The Aurochs is of very large 526 MANUAL OF ZOOLOGY. size, considerably exceeding the common Ox in bulk. It still occurs in the forests of the Caucasus in a wild state, but it no longer occurs wild in Europe, if we except a herd maintained by the Czar in one of the forests of Lithuania. Nearly allied to the Aurochs is the American Bison or Buffalo (Bison Ameri- canns). This species formerly occurred in innumerable herds in the prairies of North America, but it has been gradually driven westwards, and has been much reduced in numbers. Two other very well known forms are the Cape Buffalo (Bu- balus Coffer) and the common Buffalo (Bubalus bubalis). The former of these occurs in southern and eastern Africa, and the latter is domesticated in India and in many parts of the south of Asia. The horns in both species are of large size, and their bases are confluent, so that the forehead is protected by a bony plate of considerable thickness. The last of the Oxen which deserves notice is the curious Musk-ox (Ovibos moschatus}. This singular animal is at the present day a native of Arctic America, and is remarkable for the great length of the hair. It is called the Musk-ox, because it gives out a musky odour. Like the Reindeer, the Musk-ox had formerly a much wider geographical range than it has at present ; the conditions of climate which are necessary for its existence having at that time extended over a very much larger area than at present. The Musk-ox, in fact, in Post- tertiary times is known to have extended over the greater part of Europe, remains of it occurring abundantly in certain of the bone-caves of France. CHAPTER LXXVIIL HYRACOIDEA AND PROBOSCIDEA. ORDER VII. HYRACOIDEA. — This is a very small order which has been constituted by Huxley for the reception of two or three little animals, which make up the single genus Hyrax. These have been usually placed in the immediate neighbour- hood of the Rhinoceros, to which they have some decided affinities, and they are still retained by Owen in the section of the Perissodactyle Ungulates. The order is distinguished by the following characters : — There are no canine teeth, and the incisors of the upper jaw are long and curved, and grow from permanent pulps, as they PROBOSCIDEA. $2? do in the Rodents (such as the Beaver, Rat, &c.) The molar teeth are singularly like those of the Rhinoceros. According to Huxley, the dental formula of the aged animal is — 2—2 o—o 4—4 3—3 The fore-feet are tetradactylous, the hind-feet tridactylous, and all the toes have rounded hoof-like nails, with the ex- ception of the inner toes of the hind-feet, which have an obliquely-curved nail. There are no clavicles. The nose and ears are short, and the tail is represented by a mere tubercle. The placenta is deciduate and zonary, whereas in the Ungulates it is non-deciduate. Two or three species si Hyrax are known, but they resemble one another in all essential particulars. They are all gregarious little animals, living in holes of the rocks, and capable of domestication. One species is said to be arboreal in its habits. The " coney" of Scripture is believed to be the Hyrax Syriacus, which occurs in the rocky parts of Syria and Palestine. Another species — the Hyrax C#//drozoon. HYDROSOMA (Gr. hudra; and soma, body). The entire organism of any Hydrozoon. HYDROTHECA (Gr. hudra; and the&e, a ease). The little chitinous cups in which the polypites of the Sertularida and Campanularida are protected. HYDROZOA (Gr. hudra ; and zob'n, animal). The class of the Ccelenterata, which comprises animals constructed after the type of the Hydra. HYMENOPTERA (Gr. humen, a membrane ; pteron, a wing). An order of In- sects (comprising Bees, Ants, &c.) characterised by the possession of four membranous wings. HTOID (Gr. U; eidos, form). The bone which supports the tongue in Ver- tebrates, and derives its name from its resemblance in man to the Greek letter U. HTPOSTOME (Gr. hupo, under ; stoma, mouth). The upper lip, or " labrum," of certain Crustacea (e.g., Trilobites). HYRACOIDEA (Gr. hurax, a shrew ; eidos, form). An order of the Mammalia constituted for the reception of the siugle genus Hyrax. ICHTHYODORTTLITE (Gr. ichthus, fish ; dorus, spear ; lithos, stone). The fossil fin-spines of Fishes. IOHTHYOMORPHA (Gr. ichthus ; morphe, shape). An order of Amphibians, often called Urodela, comprising the fish-like Newts, &c. ICHTHYOPHTHIRA (Gr. ichthus ; phtlwir, a louse). An order of Crustacea com- prising animals which are parasitic upon Fishes. ICHTHYOPSIDA (Gr. ichthus ; ops is, appearance). The primary division of Vertebrata, comprising the Fishes and Amphibia. Often spoken of as the Branchiate Vertebrata. ICHTHYOPTERYGIA (Gr. ichthus ; pterux, wing). An extinct order of Reptiles. ICHTHYOSAURiA(Gr. ichthus ; saura, lizard). Synonymous with Ichthyopterygia. ILIUM. The haunch-bone, one of the bones of the pelvic arch in the higher Vertebrates. IMAGO (Lat. an image or apparition). The perfect insect, after it has under- gone its metamorphoses. IMBRICATED. Applied to scales or plates which overlap one another like tiles. INCISOR (Lat. incido, I cut). The cutting teeth fixed in the intermaxillary bones of the Mammalia, and the corresponding teeth in the lower jaw. INEQUILATERAL. Having the two sides unequal, as in the case of the shells of the ordinary bivalves (Lamellibranchiata). When applied to the shells of the Foraminifera, it implies that the convolutions ot the shell do not lie in the same plane, but are obliquely woiind round an axis. INEQUIVALVE. Composed of two unequal pieces or valves. INFUNDIBDLUM (Lat. for funnel). The tube formed by the coalescence or apposition of the epipodia 'in the Cephalojwda. Commonly termed the " funnel," or " siphon." INFUSORIA (Lat. infusum, an infusion). A class of Protozoa, so called be- cause they are often developed in organic infusions. INGUINAL (Lat. inguen, groin). Connected with, or situated upon, the groin. GLOSSARY. 587 INOPERCULATA (Lat. in, without ; operculum, a lid). The division of pul- monate Gasteropoda in which there is no shelly or horny plate (operculum) by which the shell is closed when the animal is withdrawn within it. INSECTA (Lat. inseco, I cut into). The class of Articulate animals commonly known as Insects. INSECTIVORA (Lat. insectum, an insect ; voro, I devour). An order of Mammals. INSECTIVOROUS. Living upon Insects. INSESSORES (Lat. insedeo, I sit upon). The order of the Perching Birds, often called Passeres. INTERAMBULACRA. The rows of plates in an Echinoderm which are not per- forated for the emission of the " tube-feet." INTERMAXILL.E, or PR^MAXILL^E. The two bones which are situated between the two superior maxillae in Vertebrata. In man, and some monkeys, the prse- maxillse a-nchylose with the maxillse, so as to be irrecognisable in the adult. INTUSSUSCEPTION (Lat. intus, within ; suscipio, I take up). The act of taking foreign matter into a living being. INVERTEBRATA (Lat. in, without ; vertebra, a bone of the back). Animals without a spinal column or backbone. ISCHIUM (Gr. ischion, the hip). One of the bones of the pelvic arch, in Ver- tebrates. ISOPODA (Gr. isos, equal ; poda, feet). An order of Crustacea in which the feet are like one another and equal. JUGULAR (Lat. jvgulum, the throat). Connected with, or placed upon, the throat. Applied to the ventral fins of fishes when they are placed beneath or in advance of the pectorals. KAINOZOIC (Gr. kainos, recent ; zoe, life). The Tertiary period in Geology, comprising those formations in which the organic remains approximate more or less closely to the existing fauna and flora. KERATODE (Gr. keras, horn ; eidos, form). The horny substance of which the skeleton of many sponges is made up. KERATOSA. The division of Sponges in which the skeleton is composed of keratode. LABIUM (Lat. for lip). Restricted to the lower lip of Articulate animals. LABRUM (Lat. for lip). Restricted to the upper lip of Articulate animals. LABYRINTHODONTIA (Gr. labyrinthos, a labyrinth; odous, tooth). An extinct order of Amphibia, so called from the complex microscopic structure of the teeth. LACERTILIA (Lat. lacerta, a lizard). An order of Reptilia comprising the Lizards and Slow-worms. L^SMODIPODA (Gr. laima, throat; dis, twice; poda, feet). An order of Crus- tacea, so called because they have two feet placed far forwards, as it were under the throat. LAMELLIBRANCHIATA (Lat. lamella, a plate; Gr. Iragchia, gill). The class of Mollusca, comprising the ordinary bivalves, characterised by the possession of lamellar gills. LAMELLIROSTRES (Lat. lamella, a plate ; rostrum, beak). The flat-billed Swimming Birds (Natatores), such as Ducks. Geese, Swans, &c. LARVA (Lat. a mask). The insect in its first stage after its emergence from the egg, when it is usually very different from the adult. LARYNX. The upper part of the wind-pipe, forming a cavity with appropri- ate muscles and cartilages, situated beneath the hyoid bone, and concerned in Mammals in the production of vocal sounds. LENTICULAR (Lat. lens, a bean). Shaped like a biconvex lens. LEPIDOPTERA (Gr. lepis, a scale ; pteron, a wing). An order of Insects, com- prising Butterflies and Moths, characterised by possessing four wings which are usually covered with minute scales. LEPIDOTA (Gr. lepis, a scale). Formerly applied to the order Dipnoi, con- taining the Mud-fishes (Lepidosiren). 588 GLOSSARY. LEPTOCARDIA (Gr. leptos, slender, small ; cardia, heart). The name given by Miiller to the order of Fishes comprising the Lancelot, now called Pharyn- gobranchii. LIGAMENTUM NUCEUE (Lat. nucka, the nape of the neck). The band of elastic fibres by which the weight of the head in Mammalia is supported. LIGULA (Lat. ligula, a little tongue). The upper flexible portion of the labium or lower lip in Insects. LINGUAL (Lat. lingua, the tongue). Connected with the tongue. LISSENCEPHALA (Gr. lissox, smooth ; eykeplmlos, brain). A primary division of Mammalia, according to Owen, in which the cerebral hemispheres are smooth or have few convolutions. LlTHOCYSTS (Gr. litkos, a stone ; kustis, a cyst). The sense-organs or "mar- ginal bodies " of the Lncernarida or Steyanophthalmate Medusae. LONGIPENNAT.E (Lat. longus, long ; penna, wing). A group of the Natatorial birds. LONGIROSTRES (Lat. long us ; rostrum, beak). A group of the Wading birds. LOPHOPHORE (Gr. lopJtos, a crest ; andphero, I carry). The disc or stage upon which the tentacles of the Polyzoa are borne. LOPHYROPODA (Gr. lopJiouroSf having stiff hairs ; and poda, feet). An order of Crustacea. LORICA (Lat. a breast-plate). Applied to the protective case with which certain Infusoria are provided. LORICATA (Lat. lorica, a cuirass). The division of Reptiles comprising the Clielonia and CrocodiUa, in which bony plates are developed in the skin (derma). LUCERNARIDA (Lat. lucerna, a lamp). An order of the Hydrozoa. LUMBAR (Lat. lumbus, loin). Connected with the loins. LUNATE (Lat. luna, moon). Crescentic in shape. LYENCEPHALA (Gr. luo, I loose; egkephalos, brain). A primary division of Mammals, according to Owen. MACRODACTYLI (Gr. makros, long ; daktulos, a finger). A group of the Wading birds. MACRURA (Gr. makros, long; oura, tail). A tribe of Decapod Crustaceans with long tails (e.g., the Lobster, Shrimp, &c.) MADREPORIFORM. Perforated with small holes, like a coral ; applied to the tubercle by which the ambulacral system of the Echinoderms mostly com- municates with the exterior. MALACOSTRACA (Gr. malakos, soft ; ostrakon, shell). A division of Crustacea. Originally applied by Aristotle to the entire class Crustacea, because their shells were softer than those of the Molhisca. MALLOPHAGA (Gr. mallos, a fleece ; phago, I eat). An order of Insects which are mostly parasitic upon birds. MAMMALIA (Lat. mamma, the breast). The class of Vertebrate animals which suckle their young, MANDIBLE (Lat. mandibulum, a jaw). The upper pair of jaws in Insects ; also applied to one of the pairs of jaws in Crustacea and Spiders, to the beak of Cephalopods, the lower jaw of Vertebrates, &c. MANTLE. The external integument of most of the Mollusca, which is largely- developed, and forms a cloak in which the viscera are protected. Techni- cally called the "pallium." MANUBRIUM (Lat. a handle). The polypite which is suspended from the roof of the swimming-bell of a Medusa, or from the gonocalyx of a medusiform gonophore amongst the Hydrozoa. MANUS (Lat. the hand). The hand of the higher Vertebrates. MARSIPOBRANCHII (Gr. marsipos, a pouch ; Iragchia, gill). The order of Fishes comprising the Hag-fishes and Lampreys, with pouch-like gills. MARSUPIALIA (Lat. marsupium, a pouch). An order of Mammals in which the females mostly have an abdominal pouch in which the young are carried. MASTAX (Gr. mouth). The muscular pharynx or "buccal funnel" into which the mouth opens in most of the Rotifera. MASTICATORY (Lat. mastico, I chew). Applied to parts adapted for chewing. GLOSSARY. 589 MAXILLJE (Lat. jaws). The inferior pair or pairs of jaws in the Arthropoda (Insects, Crustacea, &c.) The upper jaw-bones of Vertebrates. MAXILLIPFIDES (Lat. maxillae, jaws ; pes, the foot). The limbs in Crustacea and Myriapoda which are converted into masticatory organs, and are com- monly called " foot-jaws." MEDULLA (Lat. marrow). Applied to the marrow of bones, or to the spinal cord, with or without the adjective " spinal is." MEDUSAE. An order of Hydrozoa, commonly known as Jelly-fishes (Disco- phora, or Acafephce), so called because of the resemblance of their tentacles to the snaky hair of the Medusa. Many Medusae are now known to be merely the gonophores of Hydrozoa. MEDCJSIFORM. Resembling a Medusa in shape. MEDUSOID. Like a Medusa; used substantively to designate the medusiform gonophores of the Hydrozoa. MEMBRANA NiCTfTANS (Lat. nicto, I wink). The third eyelid of Birds, &c. MENTUM (Lat. the chin). The basal portion of the labium or lower lip in Insects. MEROSTOMATA (Gr. meron, thigh ; stoma, mouth). An order of Crustacea in which the appendages which are placed round the mouth, and which offi- ciate as jaws, have their free extremities developed into walking or pre- hensile organs. MESENTERIES (Gr. mesos, intermediate ; enteron, intestine). In a restricted sense, the vertical plates which divide the somatic cavity of a Sea-anemone (Actinia) into chambers. MESOPODIUM (Gr. mesos, middle ; pom, foot). The middle portion of the " foot " of Molluscs. MESOSTERNUM (Gr. mesos, intermediate ; sternon, the breast-bone). The middle portion of the sternum, intervening between the attachment of the second pair of ribs and the xiphoid cartilage (xip/iisternum). MESOTHORAX (Gr. mesos; and thorax, the chest). The middle ring of the thorax in Insects. MESOZOIC (Gr. mesos; and zoe, life). The Secondary period in Geology. METACARPUS (Gr. meta, after ; karpos, the wrist). The bones which form the " root of the hand," and intervene between the wrist and the fingers. METAMORPHOSIS (Gr. meta, implying change ; morphe, shape). The changes of form which certain animals undergo in passing from their younger to their fully-grown condition. METAPODIUM (Gr. meta, after ; pous, the foot). The posterior lobe of the foot in Mollusca; often called the " operculigerous lobe," because it deve- lops the operculum when this structure is present. METASTOMA (Gr. meta, after ; stoma, mouth). The plate which closes the mouth posteriorly in the Crustacea. METATARSUS (Gr. meta, after ; tarsos, the instep). The bones which inter- vene between the bones of the ankle (tarsus) and the digits in the hind-foot of the higher Vertebrates. METATHORAX (Gr. meta, after ; thorax, the chest). The posterior ring of the thorax in Insects. MIMETIC (Gr. mimetikos, imitative). Applied to organs or animals which re- semble each other in external appearance, but not in essential structure. MOLARS (Lat. mola, a mill). The " grinders " in man, or the teeth in diphyo- dont Mammals which are not preceded by milk-teeth. MOLLUSCA (Lat. mollis, soft). The sub-kingdom which includes the Shell- fish proper, the Polyzoa, the Tunicata, and the Lamp-shells ; so called from the generally soft nature of their bodies. MOLLUSCOIDA (Mollusca ; Gr. eidos, form). The lower division of the Mollusca, comprising the Polyzoa, Tunicata, and Brachiopoda. MONADS (Gr. monas, unity). Microscopical organisms of an extremely simple character, developed in organic infusions. MONOCULOUS. Possessed of only one eye. MONODELPHIA (Gr. monos, single ; defphus, womb). The division of Mammalia in which the uterus is single. 5QO GLOSSARY. MONCECIOUS (Gr. monos, single ; oikos, house). Applied to individuals in which the sexes are united. MONOMYARY (Gr. monos, single ; imion, muscle). Applied to those bivalves (Lamellibranchiata) in which the shell is closed by a single adductor muscle. MONOPHYODONT (Gr. monos ; phuo, I generate; odous, tooth). Applied to those Mammals in which only a single set of teeth is ever developed. MONOTHALAMOUS (Gr. monos ; and thalamos, chamber). Possessing only a single chamber. Applied to the shells of Foraminifera and Mollusca. MONOTREMATA (Gr. monos ; trema, aperture). The order of Mammals com- prising the Duck-mole and Echidna, in which the intestinal canal opens into a " cloaca " common to the ducts of the urinary and generative organs. MULTILOCULAR (Lat. multus, many ; loculus, a little purse). Divided into many chambers. MULTIVALVE. Applied to shells which are composed of many pieces. MULTUNGULA (Lat. multus, many ; ungula, hoof). The division of Perisso- dactyle Ungulates, in which each foot has more than a single hoof. MYELON (Gr. muelos, marrow). The spinal cord of Vertebrates. MYRIAPODA (Gr. murios, ten thousand; poda, feet). A class of A rthropoda comprising the Centipedes and their allies, characterised by their numer- ous feet. NACREOUS (Fr. nacre, mother-of-pearl, originally Oriental). Pearly, of the texture of mother-of-pearl. NATATORES (Lat. nare, to swim). The order of the Swimming birds. NATATORY (Lat. nare, to swim). Formed for swimming. NAUTILOID. Resembling the shell of the Nautilus in shape. NECTOCALYX (Gr. necho, I swim; kalux, cup). The swimming-bell or "disc" of a Medusa or Jelly-fish. NEMATELMIA (Gr. nema, thread ; lidmins, a worm). The division of Scolecida comprising the Round-worms, Thread-worms, &c. NEMATOCYSTS (Gr. nema, thread ; Jcustis, a bag). The thread-cells of the Coe- lenterata. (See Cnidse). NEMATOIDEA (Gr. nema, thread ; eidos, form). An order of Scolecida compris- ing the Thread- worms, Vinegar-eels, &c. NEMATOPHORES (Gr. nema, thread ; p/iero, I carry). Caecal processes found on the coanosarc of certain of the Sertularida, containing numerous thread- cells at their extremities. NEMERTIDA (Gr. Nemertes, proper name). A division of the Turbellarian Worms, commonly called "Ribbon- worms." NERVURES (Lat. nervus, a sinew). The ribs which support the membranous wings of insects. NEURAL (Gr. neuron, a nerve). Connected with the nervous system. NEURAPOPHYSIS (Gr. neuron, a nerve ; apop/msis, a projecting part). The " spinous process " of a vertebra, or the process formed at the point of junc- tion of the neural arches. NEUROPODIUM (Gr. neuron, a nerve ; pous, the foot). The ventral or inferior division of the "foot-tubercle" of an Anndide ; often called the "ventral oar." NEDROPTERA (Gr. neuron; and pteron, a wing). An order of Insects charac- terised by four membranous wings with numerous reticulated nervures (e.g., Dragon-flies). NEUTER (Lat. neither the one nor the other). Havingno fully developed sex. NIDIFICATION (Lat. nidus, a nest ; facio, I make). The building of a nest. NOCTURNAL (Lat. nox, night). Applied to animals which are active by night. NORMAL (Lat. norma, a rule). Conforming to the ordinary standard. NOTOBRANCHIATA (Gr. nofos, the back ; and bragchia, gill). Carrying the gills upon the back ; applied to a division of the Annelida. NOTOCHORD (Gr. notos, back ; chorde, string). A cellular rod which is devel- oped in the embryo of Vertebrates immediately beneath the spinal cord, and which is usually replaced in the adult by the vertebral column. Often it is spoken of as the " chorda dorsalis." GLOSSARY, 591 NOTOPODIUM (Gr. notos, the back ; and pous, the foot). The dorsal division of one of the foot-tubercles or parapoclia of an Annelide ; often called the " dorsal oar." NUCLEATED. Possessing a nucleus or central particle. NUCLEOLUS. 1. The minute solid particle in the interior of the nucleus of some cells. 2. The minute spherical particle attached to the exterior of the " nucleus," or ovary, of certain Infusoria, performing the functions of a testicle. NUCLEUS (Lat. nucleus, a kernel). 1. The solid or vesicular body found in many cells. 2. The solid rod, or band-shaped body, found in the interior of many of the Protozoa, and having, in certain of|£hem, the functions of an ovary. 3. The " madreporiform tubercle " of the Echinodermata. 4. The embryonic shell which is retained to form the apex of the adult shell in many of the Mollusca. NUDIBRANCHIATA (Lat. nudus, naked ; and Gr. Iragchia, gill). An order of the Gasteropoda in which the gills are naked. NYMPHS. The active pupae of certain Insects. OCCIPITAL. Connected with the occiput, or the back part of the head. OCEANIC. Applied to animals which inhabit the open ocean (= pelagic). OCELLI (Lat. diminutive of oculus, eye). The simple eyes of many Echino- derms, Spiders, Crustaceans, Molluscs, &c. OCTOPODA (Gr. octo, eight ; pous, foot). The tribe of Cuttle-fishes with eight arms attached to the head. ODONTOCETI (Gr. odous, tooth; ketos, whale). The "toothed" Whales, in contradistinction to the "whalebone " Whales. ODONTOID (Gr. odous ; eidos, form). The " odontoid process " is the centrum or body of the first cervieal vertebra (atlas}. It is detached from the atlas, and is usually anchylosed with the second cervical vertebra (axis), and it forms the pivot upon which the head rotates. ODONTOPHORE (Gr. odous, tooth ; phero, I carry). The so-called "tongue," or masticatory apparatus of Gasteropoda, Pteropoda, and Cephalopoda. (ESOPHAGUS. The gullet or tube leading from the mouth to the stomach. OLIGOCH^TA (Gr. oligos, few; chaite, hair). An order of Annelida, compris- ing the Earth-worms, in which there are few bristles. OMASUM (Lat. bullock's tripe). The third stomach of Ruminants, commonly called the psalterium, or many -plies. OMNIVOROUS ( Lat. omnia, everything; voro, I devour). Feeding indiscrimin- ately upon all sorts of food. OPERCULATA (Lat. operculum, a lid). A division of pulmonate Gasteropoda, in which the shell is closed by an operculum. OPERCULUM. A horny or shelly plate developed in certain Mollusca upon the hinder part of the foot, and serving to close the aperture of the shell when the animal is retracted within it ; also the lid of the shell of a Balanus or Acorn-shell ; also the chain of flat bones which cover the gills in many fishes. OPHIDIA (Gr. ophis, a serpent). The order of Reptiles comprising the Snakes. OPHIDOBATRACHIA (Gr. ophis; latrachos, a frog). Sometimes applied to the order of Snake-like amphibians comprising the Ccecilice. OPHIOMORPHA (Gr. ophis; morphe, shape). The order of A mphibia comprising the Ccecilice. OPHIUROIDEA (Gr. ophis, snake ; oura, tail ; eidos, form). An order of Echin- odermata, comprising the Brittle-stars and Sand-stars. OPISTHOBRANCHIATA (Gr. opistJien, behind ; bragchia, gill). A division of Gasteropoda, in which the gills are placed on the posterior part of the body. OPISTHOCOELOUS (Gr. opisthen, behind ; koilos, hollow). Applied to vertebrae, the bodies of which are hollow or concave behind. ORAL (Lat. os, mouth). Connected with the mouth. ORNITHODELPHIA (Gr. ornis, a bird ; delphus, womb). The primary division of Mammals comprising the Monotremata. ORTHOPTERA (Gr. orthos, straight ; pteron, wing). An order of Insects. 592 GLOSSARY. OSCULA (Lat. diminutive of os, mouth). 1. The large apertures by which a sponge is perforated ("exhalant apertures''). 2. The suckers with which the Tteniada (Tapeworms and Cystic Worms) are provided. OSSICULA (Lat. diminutive of os, bone). Literally small bones. Often used to designate any hard structures of small size, such as the calcareous plates in the integument of the Star-fishes. OSTKACODA (Gr. ostrakon, a shell). An order of small Crustaceans which are enclosed in bivalve shells. OTOLITHS (Gr. ous, ear ; and lithos, stone). The calcareous bodies connected with the sense of hearing, even in its most rudimentary form. OVARIAN VESICLES or CAPSULES. The gonophores or generative buds of the Hydrozoa. OVARY (OVARIUM). The organ by which ova are produced. OVIPAROUS (Lat. ovum, an egg; and par io, I bring forth). Applied to animals which bring forth eggs, in contradistinction to those which bring forth their young alive. OVIPOSITOR (Lat. ovum and pono, I place). The organ possessed by some in- sects, by means of which the eggs are placed in a position suitable for their development. 0 vis AC. The external bag or sac in which certain of the Invertebrates carry their eggs after they are extruded from the body. OvoviviPAROUS (Lat. ovum, egg ; vivus, alive ; pario, I produce). Applied to animals which retain their eggs within the body until they are hatched. OVUM (Lat. an egg). The germ produced within the ovary, and capable under certain conditions of being developed into a new individual. PACHYDERMATA (Gr. pachus, thick ; derma, skin). An old Mammalian order constituted by Cuvier for the reception of the Rhinoceros, Hippopotamus, Elephant, &c. PALAEONTOLOGY (Gr. palaios, ancient ; and logos, discourse). The science of fossil remains or of extinct organised beings. PALAEOZOIC (Gr. palaios, ancient ; and zoe, life). Applied to the oldest of the great geological epochs. PALLIUM (Lat. pallium, a cloak). The mantle of the Molly sea. Pallial : re- lating to the mantle. Pallial line or impression : the line left in the dead shell by the muscular margin of the mantle. Pallial shell ; a shell which is secreted by, or contained within, the mantle, such as the "bone" of the Cuttle-fishes. PALLIOBRANCHIATA (Lat. pallium ; and Gr. bragchia, gill). An old name for the Bracldopoda, founded upon the belief that the system of tubes in the mantle constituted the gills. PALPI (Lat. palpo, I touch). Processes supposed to be organs of touch, de- veloped from certain of the oral appendages in Insects, Spiders, and Crus- tacea, and from the sides of the mouth in the Acephalous Molluscs. PAPILLA (Lat. for nipple). A minute soft prominence. PARAPODIA (Gr. para, beside ; poda, feet). The unarticulated lateral locomo- tive processes or " foot-tubercles " of many of the Annelida. PARIETAL (Lat. paries, a wall). Connected with the walls of a cavity or of the body. PARIETOSPLANCHNIC (Lat. paries ; Gr. splaychna, viscera). Applied to one of the nervous ganglia or the Mollusca, which supplies the walls of the body and the viscera. PARTHENOGENESIS (Gr. partlienos, a virgin ; and gignomai, to be born). Strictly speaking, confined to the production of new individuals from virgin females by means of ova without the intervention of a male. Sometimes used also to designate asexual reproduction by gemmation or fission. PATAGIUM (Lat. the border of a dress). Applied to the expansion of the in- tegument by which Bats, Flying Squirrels, and other animals support them- selves in the air. PATELLA. The knee-cap or knee-pan. A sesamoid bone developed in the tendon of insertion of the great extensor muscles of the thigh. GLOSSARY. 593 PECTINATE (Lat. pecten, a comb). Comb-like ; applied to the gills of certain Gasteropoda ; hence called Pectinibranchiata. PECTORAL (Lat. pectus, chest). Connected with, or placed upon, the chest. PERENNIBRANCHIATA (Lat. perennis, perpetual ; Gr. bragchia, gill). Applied to those Amphibia in which the gills are permanently retained throughout life. PEDAL (Lat. pes, the foot). Connected with the foot of Mollusca. PEDICELLARI^E (Lat. pedicdlm, a louse). Certain singular appendages found in many Echinoderms, attached to the surface of the body, and resembling a little beak or forceps supported on a stalk. PEDICLE (Lat. dim. of pes, the foot). A little stem. PEDIPALPI (Lat. pes, foot ; and palpo, I feel). An order of Aracknida com- prising the Scorpions, &c. PEDUNCLE (Lat. pedunculus, a stem or stalk). In a restricted sense applied to the muscular process by which certain Brachiopods are attached, and to the stem which bears the body (capitulum) in Barnacles. PEDUNCULATE. Possessing a peduncle. PELAGIC (Gr. pelayos, sea). Inhabiting the open ocean. PELVIS (Lat. for basin). Applied, from analogy, to the basal portion of the cup (calyx] of Crinoids. The bony arch with which the hind limbs are con- nected in Vertebrates. PERGAMENTACEOUS(Lat. pergamena, parchment). Of the texture of parchment. PKRICARDIUM (Gr. peri, around; hardia, heart). The serous membrane in which the heart is contained. PERIDERM (Gr. peri, around ; and derma, skin). The hard cuticular layer which is developed by the coenosarc of certain of the Hydrozoa. PERIGASTRTC (Gr. peri, around ; and gaster, stomach). The perigastric space is the cavity which surrounds the stomach and other viscera, corresponding to the abdominal cavity of the higher animals. PERIOSTRACUM (Gr. peri ; and ostrakon, shell). The layer of epidermis which covers the shell in most of the Mollusca. PERIPLAST (Gr. peri; and plasso, I mould). The intercellular substance or matrix in which the organised structures of a tissue are imbedded. PERISOME (Gr. peri; and soma, body). The coriaceous or calcareous integu- ment of the Echinodermata. PERISSODACTYLA (Gr. perissos, uneven ; daktulos, finger). Applied to those Hoofed Quadrupeds ( Ungulata) in which the feet have an uneven number of toes. PERISTOME (Gr. peri; and stoma, mouth). The space which intervenes be- tween the mouth and the margin of the calyx in Vorticeila ; also the space between the mouth and the tentacles in a Sea-anemone (Actinia) ; also the lip or margin of the mouth of a univalve shell. PERIVISCERAL (Gr. peri; and Lat. viscera, the internal organs). Applied to the space surrounding the viscera. PETALOID. Shaped like the petal of a flower. PHALANGES (Gr. phalanx, a row). The small bones composing the digits of the higher Vertebrate Normally each digit has three phalanges. PHARYNGOBRANCHII (Gr. pharugx, pharynx; Iragchia, gill). The order of Fishes comprising only the Lancelet. PHARYNX. The dilated commencement of the gullet. PHRAGMACONE (Gr. phragma, a partition ; and Jconos, a cone). The chambered portion of the internal shell of a Belemnite. PHYLACTOLJEMATA (Gr. phulasso, I guard; and laima^ throat). The divison of Polyzoa in which the mouth is provided with the arched valvular process known as the "epistome." PHYLLOCYSTS (Gr.phullon, leaf; and kmtis, a cyst). The cavities in the in- terior of the " hydrophyllia" of certain of the Oceanic Hydrozoa. PHYLLOPODA (Gr. phullon, leaf; andpous, foot). An order of Crustacea. PHYOGEMMARIA (Gr. phuo, I produce ; and Lat. gemma, bud). The small gonoblastidia of Velella, one of the Physophoridce. PHYSOGRADA (Gr. phusa, bellows or air-bladder ; and Lat. gradior, I walk). VOL. II. 2 P 594 GLOSSARY. Applied formerly to the PhysopJioridce, an order of Oceanic Hydrozoa, in which a "float" is present. PHYSOPHORID^E (Gr. phusa, air-bladder ; and phero, I carry). An order of Oceanic Hydrozoa. PHYTOID (Gr. phufon,:Si plant; and eidos, form). Plant-like. PHYTOPHAGOUS (Gr. pJiuton, a plant ; and phago, I eat). Plant-eating, or herbivorous. PINNATE (Lat. pinna, a feather). Feather-shaped, or possessing lateral pro- siaccaa PlNNlGRADA (Lat. pinna, a feather ; gradior, I walk). The group of Carni- vora comprising the Seals and Walruses, adapted for an aquatic life. Often called Pinnipedia. PINNULE (Lat. dim. of pinna). The lateral processes of the arms of Crinoids. PISCES (Lat. piscis, a fish). The class of Vertebrates comprisitig the Fishes. PLACENTA (Lat. a cake). The "after-birth," or the organ by which a vascu- lar connection is established in the higher Mammalia between the mother and the foetus. PLACENTAL. Possessing a placenta ; or connected with the placenta. PLACOID (Gr. plax, a plate ; eidos, form). Applied to the irregular bony plates, grains, or spines which are found in the skin of various fishes (Elas- mobranc/tii). PLAGIOSTOMI (Gr. plagios, transverse ; stoma, mouth). The Sharks and Rays, in which the mouth is transverse, and is placed on the under surface of the head. PLANARIDA (Gr. plane, wandering). A sub-order of the Turbellaria. PLANTIGRADE (Lat. planta, the sole of the foot ; gradior, I walk). Applying the sole of the foot to the ground in walking. PLANULA (Lat. planus, flat). The oval ciliated embryo of certain of the Hy- drozoa. PLASTRON. The lower or ventral portion of the bony case of the Chelonians. PLATYELMIA (Gr. platus, broad ; and helmins, an intestinal worm). The division of Scolecida comprising the Tapeworms, &c. PLATYRHINA (Gr. platus, broad ; rhines, nostrils). A group of the Quadrumana. PLEURA (Gr. the side). The serous membrane covering the lung in the air- breathing Vertebrates. PLEURON (Gr. pleiiron, a rib). The lateral extensions of the shell of Crustacea. PLUTEUS (Lat. a pent-house). The larval form of the Echinoidea. PNEUMATIC (Gr. pneuma, air). Filled with air. PNEUMATOCYST (Gr. pneuma, air ; and Jcustis, cyst). The air-sac or float of certain of the Oceanic Hydrozoa (PhysopJioridce). PNEUMATOPHORE (Gr. pneuma, air ; and phero, I carry). The proxima dilatation of the coenosarc in the Physophoridce which surrounds the pneumatocyst. PNEUMOSKELETON (Gr. pneuma; and skeletos, dry). The hard stnictures which are connected with the breathing organs (e.g., the shell of Molluscs). PODOPHTHALMATA (Gr. pous, foot; and ophthalmos, eye). The division of Crustacea in which the eyes are borne at the end of long foot-stalks. PODOSOMATA (Gr pous, foot ; soma, body). An order of Arachnida. POEPHAGA (Gr. poe, grass ; phago, I eat). A group of the Marsupials. POLLEX (Lat. the thumb). The innermost of the five normal digits of the anterior limb of the higher Vertebrates. In man, the thumb. POLYCYSTINA (Gr. polus, many ; and kustis, a cyst). An order of Protozoa, with foraminated siliceous shells. POLYGASTRICA (Gr. j)olus ; and gaster, stomach). The name applied by Ehrenberg to the Infusoria, under the belief that they possessed many stomachs. POLYPARY. The hard chitinous covering secreted by many of the Hydrozoa. POLYPE (Gr. polus, many ; pous, foot). Restricted to the single individual of a simple ActinozoSn, such as a Sea-anemone, or to the separate zoouis of a compound Actinozoon. Often applied indiscriminately to any of the Ccelen- terata, or even to the Polyzoa. ' GLOSSARY. 595 POLYPIDE. The separate zooid of a PolyzoSn. POLYPIDOM. The dermal system of a colony of a Hydrozoon, or Polyzob'n. POLYPITE. The separate zooid of a Hydrozoon. POLYSTOME (Gr. polus, many; and stoma, mouth). Having many mouths; applied to the Acinetce amongst the Protozoa. POLYTHALAMOUS (Gr. polus; and thalamos, chamber). Having many cham- bers ; applied to the shells of Foraminifera and Cephalopoda. POLYZOA (Gr. polus ; and zoo'n, animal). A division of the Molluscoida, com- prising compound animals, such as the Sea-mat. Sometimes called Bryozoa. POLYZOARIUM. The dermal system of the colony of a Polyzoon (= Poly- pidom). PORCELLANOUS. Of the texture of porcelain. PORIFERA (Lat. porus, a pore ; and Jero, I carry). Sometimes used to desig- nate the Foraminifera, or the Sponges. POST-ANAL. Situated behind the anus. POST (ESOPHAGEAL. Situated behind the gullet. POST-ORAL. Situated behind the mouth. PRJE-MAXILL.E (see Intermaxillce). PR^MOLARS (Lat. prce, before ; molares, the grinders). The molar teeth of Mammals which succeed the molars of the milk set of teeth. In man, the bicuspid teeth. PR^E-CESOPHAGEAL. Situated in front of the gullet. PR^E-STERNUM. The anterior portion of the breast-bone, corresponding with the manubrium sierni of human anatomy, and extending as far as the point of articulation of the second rib. PRESSIROSTRES (Lat. pressus, compressed; rostrum, beak). A group of the Grallatorial Birds. PROBOSCIDEA (Lat. proboscis, the snout). The order of Mammals comprising the Elephants. PROBOSCIS (Lat. or Gr. the snout). Applied to the spiral trunk of Lepidopter- ous Insects, to the projecting rnouth of certain Crinoids, and to the central polypite in the Mediisce. PROC(ELOUS (Gr. pro, front; Jcoilos, hollow). Applied to vertebrae, the bodies of which are hollow or concave in front. PROGLOTTIS (Gr. for the tip of the tongue). The generative segment or joint of a Tapeworm. PRO-LEGS. The false abdominal feet of Caterpillars. PRONATION (Lat. pronus, lying on the face, prone). The act of turning the palm of the hand downwards. PROPODIDM (Gr. pro, before ; pous, foot). The anterior part of the foot in Molluscs. PROSCOLEX (Gr. pro, before ; skolex, worm). The first embryonic stage of a Tapeworm. PROSOBRANCHIATA (Gr. proson, in advance of ; bragchia, a gill). A division of Gasteropodous Molluscs in whicn the gills are situated in advance of the heart. PROSOMA (Gr. pro, before ; soma, body). The anterior part of the body. PROTHORAX (Gr. pro ; and thorax, chest). The anterior ring of the thorax of insects. PROTOPODITE (Gr. protos, first ; and pous, foot). The basal segment of the typical limb of a Crustacean. PROTOPHYTA (Gr. protos; and phuton, plant). The lowest division of plants. PROTOPLASM (Gr. protos; and plasso, I mould). The elementary basis of or- ganised tissues. Sometimes used synonymously for the "sarcode" of the Protozoa. PROTOZOA (Gr. protos; and soon, animal). The lowest division of the animal kingdom. PROVENTRICULUS (Lat. pro, in front of; ventriculus, dim. of venter, belly). The cardiac portion of the stomach of birds. PROXIMAL (Lat. proximus, next). The slowly-growing, comparatively-fixed extremity of a limb or of an organism. GLOSSARY. PSALTERIUM (Lat. a stringed instrument). The third stomach of Ruminants. (See Omasum.) PSEUDEMBRYO (Gr. pseudos, false ; embruon, embryo). The larval form of an Echinoderm. PSEUDOBRANCHIA (Gr. pseudos, false ; bragchia, gill). A supplementary gill found in certain fishes, which receives arterialised blood only, and does not, therefore, assist in respiration. PSEUDOH^IMAL (Gr. pseudos, false ; and haima, blood). Applied to the vas- cular system of Annelida. PSEUDO-HEARTS. Certain contractile cavities connected with the atrial system of Brachiopoda, and long considered to be hearts. PSKUDO-NAVICELL^E (Gr. pseiidos, false ; and Navicula, a genus of Diatoms). The embryonic forms of the Gregarinidce, so called from their resemblance in shape to the Navicula. PSEUDOPODIA (Gr. pseudos; and pous, foot). The extensions of the body- substance which are put forth by the Rhizopoda at will, and which serve for locomotion and prehension. PSEUDOVA (Gr. pseudos; Lat. ovum, egg). The egg-like bodies from which the young of the viviparous Aphis are produced. PTEROPODA (Gr. pteron, wing ; and pous, foot). A class of the Mollusca which swim by means of fins attached near the head. PTEROSAURIA (Gr. pteron, wing; saura, lizard). An extinct order of Reptiles. PUBIS (Lat. pubes, hair). The share-bone ; one of the bones which enter into the composition of the pelvic arch of Vertebrates. PULMONARIA. A division of Arachnida which breathe by means of pulmo- nary sacs. PULMONATE. Possessing lungs. PULMONIFERA (Lat. puhno, a lung; and fero, I carry). The division of Mollusca which breathe by means of a pulmonary chamber. PULMOGASTEROPODA (= Pulmonifera). PUPA (Lat. a doll). The stage of an insect immediately preceding its appear- ance in a perfect condition. In the pupa-stage it is usually quiescent — when it is often called a " chrysalis " — but it is sometimes active — when it is often called a " nymph." PYLORUS (Gr. puloros, a gate-keeper). The valvular aperture between the stomach and the intestine. PYRIFORM (Lat. pyrus, a pear ; and forma, form). Pear-shaped. QUADRUMANA (Lat. quatuor, four; manus, hand). The order of Mammals comprising the Apes, Monkeys, Baboons, Lemurs, &c. RADIATA (Lat. ^radius, a ray). Formerly applied to a large number of animals which are now placed in separate sub-kingdoms (e.g., the Ccelenterata, the Bchvnodermata, the Infusoria, &c. ) RADIOLARIA (Lat. radius, a ray). A division of Protozoa. RADIUS (Lat. a spoke or ray). The innermost of the two bones of the fore- arm of the higher Vertebrates. It carries the thumb, when present, and corresponds with the tibia of the hind-limb. RAMUS (Lat. a branch). Applied to each half or branch of the lower jaw or mandible of Vertebrates. RAPTORES (Lat. rapto, I plunder). The order of the Birds of Prey. RASORES (Lat. rado, I scratch). The order of the Scratching Birds (Fowls, Pigeons, &c.) RATIT.E (Lat. rates, a raft). Applied by Huxley to the Cursorial Birds which do not fly, and have, therefore, a raft-like sternum without any median keel. RECTUM (Lat. rectus, straight). The terminal portion of the intestinal canal, opening at the surface of the body at the anns. REPTILIA (Lat. repto, I crawl). , The class of the Vertebrata comprising the Tortoises, Snakes, Lizards, Crocodiles, &c. RETICULARIA (Lat. reticulum, a net). Employed by Dr Carpenter to desig- GLOSSARY. 597 nate those Protozoa, such as the Foraminifera, in which the pseudopodia run into one another and form a network. RETICULUM (Lat. a net). The second division of the complex stomach of Ruminants, often called the "honeycomb bag." REVERSED. Applied to spiral univalves, in which the direction of the spiral is the reverse of the normal — i.e., sinistral. RHIZOPHAGA (Gr. rhiza, root ; phago, I eat). A group of the Marsupials. RHIZOPODA ((Jr. rhiza, a root ; and pous, foot). The division of Protozoa com- prising all those which are capable of emitting pseudopodia. RHYNCHOLITES (Gr. rhunckos, beak ; and lithos, stone). Beak-shaped fossils, consisting of the mandibles of Cephalopoda. RODENTIA (Lat. rodo, I gnaw). An order of the Mammals ; often called Glires (Lat. gli-s, a dormouse). ROSTRUM (Lat. rostrum, beak). The "beak" or suctorial organ formed by the appendages of the mouth in certain insects. ROTATORIA (= Rotifera). ROTIFERA. (Lat. rota, wheel ; and fe.ro t I carry). A class of the Scolecida (Annuloida) characterised by a ciliated "trochal disc." RUGOSA (Lat. rugosus, wrinkled). An extinct order of Corals. RUMEN (Lat. the throat). The first cavity of the complex stomach of Rumi- nants; often called the "paunch." RUMINANTIA (Lat. ruminor, I chew the cud). The group of Hoofed Quadru- peds (Ungulata) which " ruminate" or chew the cud. SACRUM. The vertebrae (usually anchylosed) which unite with the haunch- bonqs (ilia) to form the pelvis. SAND-CANAL (•= STONE-CANAL). The tube by which water is conveyed from the exterior to the ambulacral system of the Echinodermata. SARCODE (Gr. sarx, flesh ; eidos, form). The jelly-like substance of which the bodies of Protozoa are composed. It is an albuminous body containing oil- granules, and is sometimes called "animal protoplasm." SARCOIDS (Gr. sarx; and eidos, form). The separate amoebiform particles which in the aggregate make up the " flesh" of a Sponge. SAURIA (Gr. saura, a lizard). Any lizard-like Reptile is often spoken of as a "Saurian;" but the term is sometimes restricted to the Crocodiles alone, or to the Crocodiles and Lacertilians. SAUROBATRACHIA (Gr. saura; batracJios, frog). Sometimes applied to the order of the tailed Amphibians (Urodela). SAUROPSIDA (Gr. saura; and opsis, appearance). The name given by Huxley to the two classes of the Birds and Reptiles collectively. SAUROPTERYGIA (Gr. saura; pterux, wing). An extinct order of Reptiles, called by Huxley Plesiosauria, from the typical genus Plesiosaurus. SAURURJE (Gr. saura; oura, tail). The extinct order of Birds comprising only the Archceopteryx, SCANSORES (Lat. scand'o, I climb). The order of the Climbing Birds (Parrots, Woodpeckers, &c. ) SCAPHOGNATHITE (Gr. skaphos, boat; and gnatlios, jaw). The boat-shaped appendage (epipodite) of the second pair of maxillae in the Lobster ; the function of which is to spoon out the water from the branchial chamber. SCAPULA (Lat. for shoulder-blade). The shoulder-blade of the pectoral arch of Vertebrates ; in a restricted sense, the row of plates in the cup of Crinoids, which give origin to the arms, and are usually called the "axillary radials." SCLERENCHYMA (Gr. sMeros, hard ; and enchuma, tissue). The calcareous tissue of which a coral is composed. SCLERITES (Gr. skleros}. The calcareous spicules which are scattered in the soft tissues of certain A ctinozoa. SCLEROBASIC (Gr. skleros, hard ; basis, pedestal). The coral which is produced by the outer surface of the integument in certain Actinozoa (e.g., Red Coral), and forms a solid axis which is invested by the soft parts of the animal. It is called " foot- secretion" by Mr Dana. 598 GLOSSARY. SCLEKODERMIC (Gr. sUeros ; and derma, skin). Applied to the corallum which is deposited within the tissues of certain Actinozoa, and is called "tissue- secretion " by Mr Dana. SCLEROTIC (Gr. skleros, hard). The outer dense fibrous coat of the eye. SCOLECIDA (Gr. skolex, worm). A division of the Annuloida. SCOLEX (Gr. skolex). The embryonic stage of Tapeworm, formerly known as a "Cystic Worm." SCUTA (Lat. scutum, a shield). Applied to any shield-like plates ; especially to those which are developed in the integument of many Reptiles. SELACHIA or SELACHII (Gr. selachos, a cartilaginous fish, probably a shark The sub-order of Elasmobranchii comprising the Sharks and Dog-fishes. SEPIOSTAIRE. The internal shell of the Cuttle-fish, commonly known as the "cuttle-bone." SEPTA. Partitions. SERPENTIFORM. "Resembling a serpent in shape. SERTULARIDA (Lat. sertum, a wreath). An order of Hydrozoa. SESSILE (Lat. sedo, I sit). Not supported upon a stalk or peduncle ; attached by a base. SET.E (Lat. bristles). Bristles, or long stiff hairs. SETIFEROUS. Supporting bristles. SETIGERODS (= Setiferous). SETOSE. Bristly. SILICEOUS (Lat. silex, flint). Composed of flint. SINISTRAL (Lat. sinistra, the left hand). Left-handed; applied to the direc- tion of the spiral in certain shells, which are said to be " reversed." SINUS (Lat. sinus, a bay). A dilated vein or blood-receptacle. SIPHON (Gr. siphon, a tube). Applied to the respiratory tubes in the Mollusca; also to other tubes of different functions. SIPHONOPHORA (Gr. siphon; and phero, I carry). A division of the Hydrozoa, comprising the Oceanic forms (Calycophoridce and PhysophoriJce). SIPHONOSTOMATA (Gr. siphon ; and stoma, mouth). The division of Go.s- teropodous Molluscs, in which the aperture of the shell is not " entire," but possesses a notch or tube for the emission of the respiratory siphon. SIPHUNCLE (Lat. sipftunculus, a little tube). The tube which connects together the various chambers of the shell of certain Cephalopoda (e.g., the Pearly Nautilus). SIPUNCULOIDEA (Lat. siphunculus, a little siphon). A class of Anarthropoda (A nnulosa). SIRENIA (Gr. seiren, a mermaid). The order of Mammalia comprising the Dugongs and Manatees. SOLIDUNGULA (Lat. solidus, solid ; ungula, a hoof). The group of Hoofed Quadrupeds comprising the Horse, Ass, and Zebra, in which each, foot has only a single solid hoof. Often called Solipedia. SOMATIC (Gr. soma,, body). Connected with the body. SOMATOCYST (Gr. soma ; and fcu-stis, a cyst). A peculiar cavity in the coenosarc of the Calycophoridce (Hydrozoa}. SOMITE (Gr. soma,. A single segment in the body of an Articulate animal. SPERMARIUM. The organ in which spermatozoa are produced. SPERM ATO PROBES (Gr. sperma, seed ; phero, I carry). The cylindrical cap- sules of the Cephalopoda, which carry the spermatozoa ; sometimes called the " moving filaments of Needham." SPERMATOZOA (Gr. sperma, seed ; and zoon, animal). The microscopic fila- ments which form the essential generative element of the male. SPICULA (Lat. spiculum, a point). Pointed needle-shaped bodies. SPINNERETS. The organs by means of which Spiders and Caterpillars spin threads. SPIRACLES (Lat. spiro, I breathe). The breathing-pores, or apertures of the breathing-tubes (tracheae) of Insects. Also the single nostril of the Hag- fishes, the " blow-hole " of Cetaceans, &c. SPLANCHNOSKELETON (Gr. splaychna, viscera ; sMetos, dry). The hard GLOSSARY. 599 structures occasionally developed in connection with the internal organs or viscera. SPONGE-PARTICLES. (See Sarcoids.) SPONGIDA (Or. spogyos, a sponge). The division of Protozoa commonly known as sponges. SPORES (Gr. spora, seed). Germs, usually of plants; in a restricted sense, the reproductive "gemmules" of certain Sponges. SPOROSACS (Gr. spora, seed; and sakkos, a bag). The simple generative buds of certain Hydrozoa, in which the medusoid structure is not deve- loped. SQUAMATA (Lat. squama, a scale). The division of Reptiles comprising the 0/t/tidia and Lacertilla in which the integument develops horny scales, but there are no dermal ossifications. STATOBLASTS (Gr. statos, stationary ; blastos, bud). Certain reproductive buds developed in the interior of Polyzoa, but not liberated until the death of the parent organism. STEGANOPHTHALMATA (Gr. ster/anos, covered ; and ophthalmias, the eye). Applied by Edward Forbes to certain Medusce, in which the sense-organs ("marginal bodies") are protected by a sort of hood. The Steganoph- thalmata are now separated from the true Medusidce, and placed in a sepa- rate division under the name Lucernarida. STELLERIDA (Lat. stella, star). Sometimes employed to designate the order of the Star-fishes STKLLIFORM. Star-shaped. STEMMATA (Gr. stemma, garland). The simple eyes, or (t ocelli," of certain animals, such as Insects, Spiders, and Crustacea. STERNUM (Gr. sternon). The breast-bone. STIGMATA. The breathing-pores in Insects and Arachnida. STOLON (Gr. stolos, a sending forth). Offshoots. — The connecting processes of sarcode, in Foraminifera ; the connecting tube in the social Ascidians; the processes sent out by the coenosarc of certain Actinozoa. STOMAPODA (Gr. stoma, mouth ; pons, foot). An order of Crustacea. STOMATODE (Gr. stoma}. Possessing a mouth. The Infusoria are thus often called the Stomatode Protozoa. STREPSTPTERA (Gr strepho, I twist ; and pteron, wing). An order of Insects in which the anterior wings are represented by twisted rudiments. STREPSIRHINA (Gr. strepho, I twist ; rhines, nostrils). A group of the Quadrumana, often spoken of as Prosimice. STROBILA (Gr. strobilos, a top, or fir-cone). The adult tapeworm with its generative segments or proglottides ; also applied to one of the stages in the life-history of the Lucernarida. STYLIFORM (Lat. stylus, a pointed instrument ; forma, form). Pointed in shape. SUB-CALCAREOUS. Somewhat calcareous. SUB-CENTRAL. Nearly central, but not quite. SUB-PEDUNCULATE. Supported upon a very short stem. SUB-SESSILE. Nearly sessile, or without a stalk. SUPINATION* (Lat. $uf)imi$, lying with the face upwards). The act of turning the hand with the palm upwards. SUTURE (Lat. suo, I sew). The line of junction of two parts which are immovably connected together. Applied to the line where the whorls of a univalve shell join one another; also to the lines made upon the exterior of the shell of a chambered Cephalopod by the margins of the septa. SWIMMERETS. The limbs of Crustacea, which are adapted for swimming. SYMPFIYSIS (Gr. snmphusis, a growing together). Union of two bones in which there is no motion or but a very limited amount. SYNAPTICUL^E (Gr sunapto, I fasten together). Transverse props sometimes found in Corals, extending across the loculi like the bars of a grate. SYSTOLR (Gr. siistello, I contract). Applied to the contraction of any con- tractile cavity, especially the heart. 6OO GLOSSARY. TABULAE (Lat. tabula, a tablet). Horizontal plates or floors found in some Corals, extending across the cavity of the " theca," from side to side. TACTILE (Lat. tango, I touch). Connected with the sense of touch. TJBNIADA (Gr. tainia, a ribbon). The division of Scolecida comprising the Tapeworms. TJ3XIOID (Gr. tainia; and eidos, form). Kibbon-shaped, like a tapeworm. TARSO-METATARSUS. The single bone in the leg of Birds produced by the union and anchylosis of the lower or distal portion of the tarsus with the whole of the metatarsus. TARSUS (Gr. tarsos, the flat of the foot). The small bones which form the ankle (or " instep" of man), and which correspond with the wrist (carpus) of the anterior limb. TECTIBRANCHIATA (Lat. tectus, covered ; and Gr. bragchia, gills). A division of Opisthobranchiate Gasteropoda in which the gills are protected by the mantle. TEGUMENTARY (Lat. tegumentiim, a covering). Connected with the integu- ment or skin. TELEOSTEI (Gr. teleios, perfect; osteon, bone). The order of the "Bony" Fishes. TELSON (Gr. telson, a limit). The last joint in the abdomen of Crustacea; variously regarded as a segment without appendages, or as an azygos appendage. TENUIROSTRES (Lat. tennis, slender; rostrum, beak). A group of the Perching Birds characterised by their slender beaks. TERGUM (Lat. for back). The dorsal arc of the somite of an Arthropod. TERRICOLA (Lat. terra, earth ; and colo, I inhabit). Employed occasionally to designate the Earth-worms (Lumbncidte). TEST (Lat. testa, shell). The shell of Mollusca, which are for this reason sometimes called " Testacea ; " also, the calcareous case of Echinoderms.; also, the thick leathery outer tunic in the Tunicata. TESTACEOUS. Provided with a shell or hard covering. TESTIS (Lat. testis, the testicle). The organ in the male animal which pro- duces the generative fluid or semen. TETRABRANCHIATA (Gr. tetra, four ; bragchia, gill). The order of Cephalopoda, characterised by the possession of four gills. THALASSICOLLIDA (Gr. thalassa, sea; Jcolla, glue). A division of Protozoa. THECA (Gr. theke, a sheath). A sheath or receptacle. THECOSOMATA (Gr. theke; and soma, body). A division of Pteropodous Molluscs, in which the body is protected by an external shell. THERIOMORPHA (Gr. ther, beast ; morphe, shape). Applied by Owen to the order of the Tail-less Amphibians (Anoura.) THORAX (Gr. a breastplate). The chest. THREAD-CELLS. (SeeGmdse.) THYSANURA (Gr. t/iusanoi, fringes ; and oura, tail). An order of Apterous Tn sects. TIBIA (Lat. a flute). The shin-bone, being the innermost of the two bones of the leg, and corresponding with the radius in the anterior extremity. TOTIPALMAT.E (Lat. totiis, whole; palma, the palm of the hand). A group of Wading Birds in which the hallux is united to the other toes by mem- brane, so that the feet are completely webbed. TRACHEA (Gr. traclieia, the rough wind-pipe). The tube which conveys air to the lungs in the air-breathing Vertebrates. TRACHEAE. The breathing-tubes of Insects and other Articulate animals. TRACHEARIA. The division of Arachnida which breathe by means of tra- cheae. TREMATODA (Gr. trema, a pore). An order of Scolecida. TRICHOCYSTS (Gr. thrix, hair ; and kuxtis, a cyst). Peculiar cells found in certain Infusoria, and very nearly identical with the "thread-cells" of Ccelenterata. TRILOBITA (Gr. treis, three ; lobos, a lobe). An extinct order of Crustaceans. TRITOZOOIDS (Gr. tritos, third ; zoon, animal ; and eidos, form). The zooid GLOSSARY. 60 1 produced by a deuterozob'id ; that is to say, a zob'id of the third genera- tion. TROCHAL (Gr. trochos, a wheel). Wheel-shaped ; applied to the ciliated disc of the Rotifera. TROCHANTER (Gr. trecho, I turn). A process of the upper part of the thigh- bone (femur) to which are attached the muscles which rotate the limb. There may be two, or even three, trochanters present. TROCHOID (Gr. trockos, a wheel ; and eidos, form). Conical with a flat base ; applied to the shells of Foraminifera and Univalve Molluscs. TROPHI (Gr. trophos, a nourisher). The parts of the mouth in insects which are . concerned in the acquisition and preparation of food. Often called " instrumenta cibaria." TROPHOSOME (Gr. trepho, I nourish ; and soma, body). Applied collectively to the assemblage of the nutritive zob'ids of any Hydrozoon. TRUNCATED (Lat. trunco, I shorten). Abruptly cut off; applied to univalve shells, the apex of which breaks off, so that the shell becomes "decol- lated." TOBICOLA (Lat. tuba, a tube ; and colo, I inhabit). The order of Annelida which construct a tubular case in which they protect themselves. TUBICOLOUS. Inhabiting a tube. TUNICATA (Lat. tunica, a cloak). A class of Molluscoida which are enveloped in a tough leathery case or " test." TURBELLARIA (Lat. turbo, I disturb). An order of Scolecida. TURBINATED (Lat. turbo, a top). Top-shaped ; conical, with a round base. ULNA (Gr. olene, the elbow). The outermost of the two bones of the fore- arm, corresponding with the fibula of the hind-limb. UMBELLATE (Lat. umbella. a parasol). Forming an umbel — i.e., a number of nearly equal radii all proceeding from one point. UMBILICUS (Lat. for navel). The aperture seen at the base of the axis of certain univalve shells, which are then said to be "perforated" or "um- bilicated." UMBO (Lat. the boss of a shield). The beak of a bivalve shell. UMBRELLA. The contractile disc of one of the Lucernarida. UNCINATE (Lat. uncinus, a hook). Provided with hooks or bent spines. UNGUICULATE (Lat. unguis, nail). Furnished with claws. UNGULATA (Lat. ungula, hoof). The order of Mammals comprising the Hoofed Quadrupeds. UNGULATE. Furnished with expanded nails constituting hoofs. UNILOCULAR (Lat. unus, one ; and loculus, a little purse). Possessing a single cavity or chamber. Applied to the shells of Foraminifera and Mollusca. UNIVALVE (Lat. units, one ; valvce, folding doors). A shell composed of a single piece or valve. URODELA (Gr. oura, tail ; delos, visible). The order of the tailed Amphi- bians (Newts, &c. ) URTICATING CELLS (Lat. urtica, a nettle). (See Cnida?). VACUOLES (Lat. vacuus, empty). The little cavities formed in the interior of many of the Protozoa by the presence of little particles of food, usually surrounded by a little water. These are properly called "food-vacuoles," and were supposed to be stomachs by Ehrenberg. Also the clear spaces which are often seen in the tissues of many Coelenterata. VARICES (Lat. varix, a dilated vein). The ridges or spinose lines which mark the former position of the mouth in certain univalve shells. VASCULAR (Lat. vas, a vessel). Connected with the circulatory system. VELUM (Lat. a sail). The membrane which surrounds and partially closes the mouth of the " disc" of Medusae, or medusiform gonophores. VENTRAL (Lat. venter, the stomach). Relating to the inferior surface of the body. VENTRICLE (Lat. dim. ofvenfer, stomach). Applied to one of the cavities of the heart, which receives blood from the auricle. 6O2 GLOSSARY. VERMES (Lat. vermis, a worm). Sometimes employed at the present day in the same, or very nearly the same, sense as Annuloida, or as Annuloida plus the A narthropoda. VERMIFORM (Lat. vermis, worm ; and/orwa, form). Worm-like. VERTEBRA (Lat. verto, I turn). One of the bony segments of the vertebral column or back-bone. VKRTEBRATA. (Lat. vertebra, a bone of the back, from vertere, to turn). The division of the Animal Kingdom, roughly characterised by the possession of a back-bone. VESICLE (Lat. vesica, a bladder). A little sac or cyst. VIBRACULA (Lat. vibro, I shake). Long filamentous appendages found in many Polyzoa. VIBRIONES (Lat. vibro, I shake). The little moving filaments developed in organic infusions. VIPERINA (Lat. vipera, a viper). A group of the Snakes. VIVIPAROUS (Lat. vivus, alive; and pario, I bring forth). Bringing forth young alive. WHORL. The spiral turn of a univalve shell. XIPHISTERNUM (Gr. xipkos, sword ; sternon, breast-bone). The inferior or posterior segment of the sternum, corresponding with the " xiphoid carti- lage" of human anatomy. XIPHOSURA (Gr. xiphos, a sword ; and oura, tail). An order of Crustacea, comprising the JLimuli or King-Crabs, characterised by their long sword- like tails. XYLOPHAGOUS (Gr. xulon, wood; and phago, I eat). Eating wood; applied to certain Mollusca. Zoom (Gr. zoon, animal ; and eidos, like). The more or less completely inde- pendent organisms, produced by gemmation or fission, whether these re- main attached to one another or are detached and set free. ZOOPHYTE (Gr. zoon, animal ; phuton, plant). Loosely applied to many plant- like animals, such as Sponges, Corals, Sea-anemones, Sea- mats, &c. ZOOSPORES (Gr. zoon, animal; and spora, seed). The ciliated locomotive germs of some of the lowest forms of plants (Protophyta). INDEX. AARDVARK, 502. Aardwolf, 538. Abdominalia (Cirripedia), 198 ; characters of, 203 ; (Fishes), 361. Abranchiata (Vertebrata), 337. Abyla, 91. Acalephce, 95, 99. Acanthocephala, 158, 165; characters of, 168, 169. Acanthometrina, 58. Acanthopteri, 363. Acanthopterygii, 358. Acanthospongia, 64. Acarida, 226. Acarina, 224; characters and families of, 225, 226. Accipitrince, 465, 466. Acephala (Mollusca), 278. Acerotherium, 565. Acervulina, 53. Acetabula, 299, 300. Achetina, 244. Achtheres, 199. Acicula, 297. Acwulidce, 294, 297. Acineta, 71. Acipenser, 378. ,4cmoea, 295. Acorn-Shells, 200, 201. .Acrodlws, 373. uimrtreta, 275. Acteonm, 296. Actinia, 110, 112, 113, 127. Actinidce, 111-113; development of, 113. Actinomeres, 125. Actinophrys, 49, 50, 51. Actinosoma, 111. Actinozoa, 76; general characters of, 109- 111; divisions of, 111; distribution of, 129-133. Acnleus, 249. Adelarthrosomala, 224 ; characters and families of, 226, 227. JEginida}* 98. jEginnpsis, 98. jKoliddK, 292, 296. ^olis, 296. jEpiornis, 470. Agapornis, 458. Agathistega, 54. Agelacrinites, 151. Ailurus, 535. Air-bladder of Fishes, 351. Air-receptacles of Birds, 436, 437. Alcedo, 463. Alca, 445. Alces, 523. ^IZcwte, 445. Alcyonaria, 111; characters and divisions of, 119, 120 ; distribution of in time, 133. Alcyonidce, 120. Alcyonium, 120. Allantoidea, 337. Allantois, 337, 338. Alligator, 414. Alpaca, 521. Alveolus (Belemnite), 306, 307. Amber, Insects preserved in, 252. Amblyrliynchus, 413. Ambulacral system (Echinodermata), 137; of Echinus, 141 ; of Star-fishes, 145; of Ophiuroidea, 147 ; of Crinoidea, 151 ; of Holothuroidea, 153, 154. Ameivce, 411. Ametabolic Insects, 239, 241, 242. Ammodytes, 362. Ammonites, 310, 311, 312, 314. Ammonitidce, 309, 312; characters of, 310 ; distribution of, in time, 314. Amnion, 337. Amniota, 337. Amoeba, 6, 46; structure of, 47, 48; re- production of, 48. Amoebea, 47, 49, 50. Amoebina, 50. Amphibia, 337, 375; general characters of, 381, 383 ; development of, 381 ; re- spiratory organs of, 382 ; orders of, 384; distribution of, in time, 392. Amphiccelia (Crocodilia), 414, 415. Amphidiscs, 62, 63. Amphilestes, 560. Amphwxus, 326, 351, 353. Amphipneusta, 385. Amphipoda, 198; characters of, 212. Amphisbcenidce, 409. Amphispongia, 64. Amphitherium, 560, 561. Amphiuma, 385, 386. Ampullaria, 288, 295. Anacanthini, 362. Anallantoidea, 337. Anamniota, 337. Analogy, 16. Anarchropoda, 177. Anatidce, 447. Anatina, 285. Anatinidce, 284, 285. 604 INDEX. Ancyloceras, 310, 312, 314. Ancylus, 2v)6, 313. Andrias, 392. Androphores, 93. Angelina, 208. Anguillula, 171. Anguillulidce, 171. Anguis, 410. Animals and Plants, differences between, 7-11. Anisonema, 72. ^nweZida, 177; characters of, 179; pseudo- hseinal system of, 180 ; orders of, 181 ; distribution of, in time, 188; phosphores- cence of 72 ; urticating cells of, 76. Annulata (see Annelida). Annuloida, 14 ; characters and divisions of, 135-136. Annulosa, 14,177; primary divisions of, 177. Anodon, 284. Anomodontia, 419. Anomura, 214, 217. Anoplotherium, 517, 564. Anoplura, 242. Anoura, 382 ; characters of, 387-391. Anserince, 417. Ant-eaters, 500, 501. Antelopes, 518, 520, 524. Antennae, of Lobster, 197, 216 ; of Arach- nida, 222 ; of Myriapoda, 231 ; of In- secta, 238. Antennules, of Lobster, 197, 216; of Li- mulus, 210, 222. Anthracotherium, 5fi5. Anthropoid Apes, 556. Anthiw, 462. Antilopidce, 524. Antipatkidce, 116, 122, 123. Antipathes, 116. Antlia, 236, 247. Ants, 249; communities of, 250; slave- making instincts of, 250 ; relations with plant-lice, 251. Aphaniptera, 246. Aphides, 243 ; alleged parthenogenesis of, 30. Aphrodite, 186, 189. Apiocrinidce, 150, 156. Apes, 249. Aplacental Mammals, 484. Aplysia, 296. Aplysiadce, 292, 296." Apoda(Cirripedia),I9S, 204; (Amphibia), 384 .; (Fishes), 360, 362. Apodemata, 194. Apolemiadte, 94. Aporosa (Corals), 118, 133, 134. Aporrhais, 295. Appendicularia, 268, 270. Aptera, 239, 242. Apterygidce, 451, 452. Apteryx, 440, 443, 452. Aptornis, 470. Apus, 207, 220. Aquiferous system (see Water -vascular system). Ar'achnactis, 112, 113. Arachnida, 190, 191 ; characters of, 221- 224 ; somite of, 221 ; organs of the mouth of, 222 ; respiratory process of, 223 ; distribution of, in time, 230. Araince, 458. Araneida, 227; characters of, 228; webs of, 229 ; reproductive process of, 229 ; distribution of, in time, 230. Area, 284. Arcadoe, 283, 284. Arcella, 49. Arcellina, 50. Archceocidaris, 157. Archceocyathus, 64. Archceopteryx, 427, 442, 467, 469. Archencephala, 484. Archiulidce, 233. Archialus, 233. Arctisca, 225. Arctomys, 546. Ardea, 449. Ardeidce, 449. Arenicola, 187, 189. Argonauta, 256, 302 ; shell of, 303 ; re- productive process of, 302 ; hectocotylns of, 302. Argonautidce, 305. Aristotle's Lantern, 142. Armadillos, 483, 498, 500. Arms, of Star-fishes. 144; of Ophiuroidea, 147 ; of Crinoidea, 149 ; of Comatula, 150, 151 ; of Cystoidea, 152 ; of Brachio- poda, 272; of Cuttle -fishes, 300; of Nautilus, 308. Artemia, 207. Arthrogastra, 227. Arthropoda, 177; characters and divisions of, J90. Articulata, 190. Artiodactyla, 513, 515. Asaphus, 208. Ascaris, 170. Ascidiadce, 270. Ascidioida (see Tunicata). Ascidians, solitary, social, and compound, 269, 270. Ascoceras, 310. Asinm, 515. Asiphonida(LameUibranchiata\ 283, 284. Aspergillum, 2S6. Asplanchna, 176. Astarte, 285. Asteriadce, 146. Asterinidce, 146. Asteroidea, 137, 138 ; general characters of, 144, 146; families of, 146; distribu- tion of, in space, 155 ; in time, 157. Astrceidce, 132, 134. Astrognnium, 157. Astropecten, 145, 157. Astropectinidce, 146. Astrophydice, 148. Astrophyton, 147. ^l^^s, 555. Athorybiadce, 95. Athyris, 274. .4^anto, 296. ^an^dee, 293, 296. Atolls, 129, 130, 132. Atrial system (Brachinpodd), 273. Atrium (Tunicata), 267. ^Ittcftewa, 521. Auloporidce, 134. Aulosteges, 275. Aurelia, 105. Aurelia, 240. Auricula, 296. INDEX. 605 Auriculidce, 294, 296. Aurochs, 525, 566. Autophagi, 439. Aves, 337 ; general characters of, 423 ; feathers of, 424, 425 ; vertebral column of, 426, 427; beak of, 427; pectoral arch and fore-limb of, 429, 431; hind- limb of, 431, 432 ; foot of, 433 ; digestive system of, 433-435 ; respiratory system of, 436 ; circulatory system of, 437 ; ner- vous system and organs of sense of, 439; reproductive system of, 438 ; migrations of, 441 ; divisions of, 441 ; orders of, 442 ; distribution of, in time, 467-470. Avicula, 284. Avicularia, 261, 263. Aviculidce, 283, 284. Avocet, 448. Axinus, 284. Axolotl, 385, 386. Aye-Aye, 553. BABOON, 556. Babyroussa, 517. Bacteria, 35, 36. Bactrites, 315. Baculites, 310, 311, 312, 315. Badger, 536. Balcena, 505, 506, 508. Balcenidce, 505, 507, 508. Balcenodon, 564. Balcenoptera, 508. Balancers, 235, 246. Balanidce, 198, 200, 201, 203 ; distribution of, in time, 219. Balanus, 201, 202. Baleen, 505, 506, 507, 508. Balistidce, 363. Bandicoot, 495. Barrier-reefs, 129, 130, 131. Barnacle?, 200, 202. Bathybvus, 10, 55. Batides, 373. Batrachia, 387. Bats, 474, 475, 477, 487. Bear, 531, 534, 535. Beaver, 544. Bee-eaters, 463. Bees, parthenogenesis of, 31, 32 ; commu- nities of, 249. Belemnites, structure of, 307. Belemnitidce, 306, 307, 311. Belemnitella, 311. Belenmiteuthis, 311. Belinurus, 220. Bellerophina, 313. Bellerophon, 296, 313. Belodon, 415. Beloptera, 312. Beluga, 368. Beroe, 127. Beroidce, 128. Bimana, 488 ; general characters of, 558. Biology, definition of, 1. Bioplasm, 4. Bipinnaria, 146. Bird-lice, 242. Birds of Prey, 464. Bird's-head process, 261. Bison, 526. Bivalve Shell-fish, 256, 278. Bladder, contractile, of Roiifera, 174. Blastoidea, IBS'; general characters of, 152 ; distribution of, in time, 156. Blattina, 244. Blenniidce, 363. Blind-worm, 410. Boa, 406. Boidce, 406. Bombidce, 250. Book-scorpion, 227. Bopyridce, 213. Bos, 525, 566. Bothriocephaliis, 160. Botryllidce, 270. Bourgueticrinus, 150. Bovidce, 524, 525, 565. Brachiopoda, 253, 254, 255; general charac- ters of, 270-274; shell of, 271 ; arms of, 272 ; atrial system of, 273 ; nervous sys- tem of, 273; vascular system of, 273; di- visions of, 274, 275 ; distribution of, in space, 276 ; in time, 276. Brachiuna, 199. Brachymetopus, 220. Brachyura, 214; characters of, 217; de- velopment of, 217, 218. Bracts, 90 (see Hydrophyllia). Bradypodidce, 498, 563. Bradypus, 472, 499. Bramatherium, 565, 569. Branchial arches (Fishes), 345, 349. Branchial hearts (Cuttle-fishes), 301. Branchial sac (Tunicata), 267, 268, 260 ; (Lancelet), 354. Branchiata ( Vertebrata), 337. Branchi/era, 290, 294. Branchiogasteropoda, 288, 290. Branchiopoda, 206. Branchiostegal rays, 344. Branchiostoma, 354 (see Amphioxus). Branchipus, 207. Brevilinguia, 409. Brevipennatce, 444. Bruta, 498 (see Edentata). Bryozoa (see Polyzod). Bubalus, 526. Buccinidce, 291, 294. Buccinum, 291 294. • Buceridce, 460. Buffalo, 526. Bvfonidce, 390. Bulbus arteriosus, 350. Bulimus, 296. Bulla. 296. Bullidce. 292, 296. Bursaria, 71. ' Bustards, 450. Butterflies, 247. Byssus (of Lamellibranchiata), 283. CACHALOT, 509. Caducibranchiata (Amphibia), 382, 383. Cieca, intestinal (of Birds), 435. Caeca, pyloric (of Fishes), 351. Ccecilice, 384. Caiman, 415. Calamaries, 306. Calcarea (ST>onges), 63. Calceola, 275. Calceolidce, 275. Calcispongice, 63. Calice (Corals), 115. Callianiridce, 128. 6o6 INDEX. Callithrix, 555. Callograpms, 108. Catty midce, 128. Calycophoridce, 89-92; polypites of, 89; pyloric valve of, 90; tentacles of, 90; reproduction of, 91 ; development of, 91; distribution of, 108. Calyptrcea, 295. Calyptrceidce, 292, 295. Calyx (of Vurticslla), 68; (of Crinoids), 156. Camelidce, 471, 481, 520. Camelopardalidce, 520, 523. Camelus, 521. Campanularia, 88. Campanularida, 87, 88; medusiform go- nophores of, 88. Canals, of Sponges, 61 ; of A Icyonaria, 120 ; of Ctenophora, 125, 126, 127. Canidce, 538. Canis, 538, 539. Capitulum (Lepadidce), 200, 202. Capra, 525. Capreolus, 522. Caprimulgidce, 463. Caprinella, 284. Capybara, 543. Carapace, of Difflitgia, 49 ; of Arcella, 49 ; of Vaginicola, 70 ; of Crustacea, 194 ; of Lobster, 214, 215; of Crab, 217; of Chelouian Reptiles, 398, 399. Carcharias, 373. Carcharodon, 380. Carchesium, 71. Cardiadas, 284, 285. Cardimn, 285. Carinaria, 256, 293 ; distribution of, in time, 313. Carinatce, 442. Carnivora, 475, 484, 487; general charac- ters of, 530 ; divisions of, 531-541 ; dis- tribution of, in time, 567. Carpenteria, 55. Carriage spring apparatus (Brachiopoda), 272. Carteria, 117. Caryocaris, 220. Cas*s, 294. Cassowary, 452. Castor, 544. Castoridce, 544. Casuarius, 452. Catarhina, 552, 555. Catodontidce, 505, 509. Cats, 531, 539, 541. Cayia, 543. Cavicornia, 520, 524. Cavidce, 543. Cebicke, 554, 555. O.bus, 555. Cells, of Polyzoa, 258, 259, 261. Cellulose, in Ascidians, 8, 2(56. Cement-gland, of Cirripedes, 200, 201. Centipedes, 230, 231, 232. Cephalaspis, 369, 378. Cephalobranchiata. 184 (see Tubicola). Cephalopoda, 254, 255 ; general characters of, 299 ; arms of, 299, 300 ; suckers of, 299 ; funnel of, 300 ; ink-bag of, 301 ; mandibles of, 300 ; digestive system of, 301 ; branchiae of, 301 ; nervous system of, 301 ; vascular system of, 301 ; repro- duction of, 301 ; skeleton of, 303 ; divi- sions of, 304 ; distribution of, in time, 312,314. Cephalophora (Mollusca), 286. Ceplialothorax, of Crustacea, 192, 193 ; of Arachnida, 221. Cephaluna, 199. Cephea, 105. Ceratiocaris, 220. Ceratites, 310, 312, 314. Ceratodus, 377. Cercolabes, 544. Cercoleptes, 535, 536 Cere, of Birds, 433, 440. Cerianthus, 112, 127. Cerithiadce, 292, 295. Cerithmm, 295. Certhia, 462. Certhidce, 462. Cervidce, 520, 522, 565. Cervus, 623. Cestidce, 128. Cestoidea, 159 (see Tceniada). Cestracwn, 373, 379. Cestraphori, 373, 379. Cestum, 128. Cetacea, 472, 474, 475, 476, 477, 481, 483, 487 ; general characters, of, 504 ; groups of, 505-511 ; distribution of, in time, 5t54. Cetiosaurus, 415. Chceropotamus, 565. Chceropus, 496. Chcetognatha, 177, 189 Chcetonotus, 173. Chama, 284. Chameleo, 412. Chameleontidce, 412. Chamidce, 284. Charadriidce, 450. Cheilostomata, 265, 276. Cheiromydce, 553. Cheiromys, 553. Cheironectes, 496. Cheiroptera, 484, 487; general characters of, 546 ; sub-divisions of, 548 ; distribu- tion of, in time, 568. Cheir other ium, 391. Chelae, 19«; of King-crab, 209; of Scor- pion, 222, 228 ; of Book-scorpion, 227. Chelicerae, 222, 225, 228. Chelifer, 227. Chelichnus, 401. Chelonia, 397 ; general characters of, 397- 401 ; sub-divisions of, 4UO ; distribution of, in time, 401. Cheloniidce, 401, 402. Chelonobatrachia, 387 (see Anoura). Chemnitzia, 295. Chilognatha, 232. Chilupoda, 232. Chimcera, 372. Chimceridce, 371. Chimpanzee, 557. Chirotes, 410. Chiton, 256, 296. Chitonidce, 292, 295. Chlainyphorus, 500. Chlorophyll, in animals, 9. Chondropterygidce, 370. Chondrosteus, 378. Chonetes, 275. Chorda dor sails (see Notochord). Chromatophores, 299. INDEX. 607 Chrysalis, 240. Chrysochloris, 550. Chylaqueous Canals (Medusae), 96. Chylaqueous fluid, of liotifera, 175; of Annelida, 180, 186. Chylifie stomach, of Insects, 237. Chyme-mass, of Infusoria,. 67. Cicada, 243. Ciconia, 449. Cidaridce, 143. Cidaris, 140. Cilia, of Sponges, 61 ; of Infusoria, 66 ; of Actinozoa, 109; of Ctenophora, 125; of Echinus, 142 ; of Annelides, 181, 186. Cilia'a (Infusoria), 66-71. Cinclides, 113. Cimilia, 296. Cirrhi, of Annelides, 179; of Cirripedia, 200, 202; of Brachiopoda, 272; of Lance- let, 353. Cirrhopoda (see Cirripedia). Cirripedia, 198 ; general characters of, 200-203; development of, 201; shell of, 202; reproduction of, 203; divisions of, 203 ; distribution of, in time, 219. Cirrostomi, 353 (see Pharyngobranchii). Civet, 537. Cladocera, 198; characters of, 206. Clamatores, 453. Classification, 18. Clausilia, 296. Clavellinidce, 270. Cleodora, 297. Clepsine, 188. Cliidce, 298. Cliinacograpsus, 108. Clio, 298. Ciiona, 64, 65. Clitellum, 183. Cloaca, of Rotifera, 174; of Insecta, 237; of Tunicata, 267; of Amphibia, 381, 383; of Reptiles, 395; of Birds, 435; of Monotremata, 485, 489. Clupeidce, 361. Clypeastridce, 144. Cnidse, 76. Coati, 535, 536. Coccidce, 242. Coccoliths, 55, 56. Coccospheres, 55, 56. Coccosteus, 3C9, 378. Coccus, 243. Cocoon, 240. Coelenterata, 14, 74; characters of, 74-76; thread-cells of, 76; divisions of, 76. Coenenchyma, 115. Crenoecium, 259, 261. Ccenosarc, 77, 81; of Oceanic Hydrozoa, 89,92; ofPhysalia,Q5; of Velella, 94, 95. Coleoptera, 251 ; mouth of, 235; characters of, 251. Collosphcera, 59. Colobus, 555. Colossochelys, 402. Coluber, 406. Colubrina, 405, 406. Columba, 455. Columbacei, 453, 454, 455. Columbidce, 455. Colnmella, of Corals, 115; of the shells of Gasteropoda, 289. Column, of Act.inidce, 111. Colymbidce, 445. Colymbus, 445. Comarocy . Imperforata (Foraminifera), 51, 54. Implacentalia (Mammalia), 484. Individuality, general definition of, 25, 77 ; in Sponges, 65. Infundibulum, of Cephalopoda, 299, 300. Infusoria, spontaneous generation of, 35, 36 ; characters of, 66 ; divisions of, 66 ; affinities of, 72 ; Ciliated, 66 ; Suctorial, 71 ; Flagellate, 71 ; compared with Ro- tifera, 176. Inia, 511. Innocua (Ophidia), 406. Inoceramus, 284. Inoperculata, 204, 296. Insecta, 191, 233; general characters of, 233-241 ; organs of the mouth of, 235 ; wings of, 234 ; digestive system of, 236 ; tracheae of, 238 ; circulation of, 237 ; metamorphoses of, 239 ; parthenogene- sis of, 30, 31 ; sexes of, 240 ; orders of, 241 ; distribution of, in time, 252. Insectivora, 484, 488; general characters of, 549; families of, 550; distribution of, in time, 568. Insessores, 443 ; characters of, 458 ; sec- tions of, 460. Integro-pallialia, 282, 283, 284. Invertebrata, general characters of, 324, 325. Ischiodus, 372, 380. *Isis, 116, 122. Jsocardia, 285. ' Isopoda, 198; characters of, 212; distri- bution of, in time, 220. lulus, 232. Ixodes, 226. JAGUAR, 541. Jelly-fishes, urticating powers of, 76 ; na- ture of, 97, 98 ; former classification of, Jerboa, 545. KANGAROO, 493. Kangaroo-rat, 493, 494. Kellia, 285. Keratode, 60. Keratosa (Sponges), 63. King-crabs, 209, 210, 222. Kinkajou, 535, 536. Koninckia, 274. Koninckiadce, 274. LABIUM, of Lobster, 197 ; of Arachnida, 222 ; of Insecta, 236. Labrum, of Lobster, 197 ; of Trilobita, 208 ; of Scorpion, 222 ; of Insecta. 235, 236. Labyrinthodontia, 391, 392. Lacerta, 411. Lacertidce, 411. Lacertilia, 387, 397 ; general characters of, 408, 409 ; families of, 409-413 ; distribu- tion of, in time, 413. Lcemodipoda, 198; characters of, 211, 212. Lagena, 52. Lagopus, 454. Lamellibranchiata, 253, 254 ; general characters of, 278-283 ; shell of, 279 ; digestive system of, 280 ; circulatory system of, 281 ; mantle of, 280 ; bran- chiae of, 281 ; reproduction of, 282 ; muscles of, 282; habits of, 283; divi- sions of, 283 ; families of, 284, 285 ; dis- tribution of, in time, 312. Lamellirostres, 446. La-mprey, 350, 355, 356, 357. Lamp-shells, 271. Lancelot, 334, 336, 341 ; anatomy of, 353- 355. Land-salamanders, 387. Laniidce, 461. Laomedea, 88. Laridce, 445. Lark, 460, 461. Larva, of Echinodermata, 136, 137; of Echinoidea, 138 ; of 'Asteroidea, 146 ; of Ophiuroidea, 147 ; of Crinoidea, 149 ; of Holothuroidea, 153 ; of Tceniada, 161, 162,163; of Trematoda, 164; ofNemer- tida, 167 ; of Acanthocephala, 168 ; of Ichthyophthira, 199; of Cirripedia, 201 ; of Brachyura, 217; of Limulus, 211 ; of Myriapoda, 231 ; of Insecta, 239, 240 ; of Tunicata, 269 ; of Brachiopoda, 273 ; of Lamellibranchiata, 282 ; of Gastero- poda, 289. Leech, 181. Lemuridce, 553. Leopard, 541. Lepadidce, 198, 200 ; characters of, 202 ; distribution of, in time, 220. Lepas, 201. Lepidoganoidei, 367, 378. Lepidoptera, 247 ; mouth of, 236 ; charac- ters of, 247. Lepidosiren, 351, 352, 356; characters of, 375-377. Lepidosteus, 342, 3fi5, 367. Lepidota, 384 (see Dipnoi). Lepisma, 242. Leporidce, 543. Leptcena, 274. Leptocardia, 353 (see Pharyngobranchii). Lepus, 543. Lerncea, 34, 199. Libellulidce, 244. Lieberkuhnia, 5i). Ligula, 236. Limacidce, 294, 296. Limacina, 298. Limacinidce, 298. Limax, 256, 296. Limnadia, 207. Limncea, 296, 313. Limnceidce, 294, 296. Limnoria, 213. Limulus, 209, 210, 211, 220. Lingua (Insects), 236. Lingual Ribbon (Mollusca), 287. Linguatulina, 225. INDEX. 6l3 Lingula, 271, 275, 276, 277. Lingulidce, 274, 275. Lion, 531, 539, 540. Lissencephala, 484. Lithobius, 232. Lithocysts, 99, 104. Lithodomi, 283. Lithornis, 469. Littorina, 291, 295. Littorinidce, 292, 295. Lituites, 310, 312. Lituolida, 54. Liver-fluke, 165. Lizards, 408-411. Llama, 520, 521. Lobster, morphology of, 193-198 ; general anatomy of, 214-217. Lob-worm, 187, 189. Loculi, of shell of Foraminifera, 50 ; of Corals, 115. Locustina, 244. Loligo, 306, 311. Longipennatce, 445. Longirostres, 448, 450. Lophiidce, 363. Lophobranchii, 363. Lophopea, 265. Lophopore, 263, 265. Lophopus, 261, 262. Lophyropoda, 204. Loricata, 395. Love-bird, 458. Loxiadce, 460, 461. Lucernaria, 100. Lucernariadce, 99, 100. Lucernarida, 78; general characters of, 99; umbrella of, 99; divisions of, 99; development of, 101 ; structure of re- productive zooids of, 103, 104. Lucina, 285. Lucinidcf:, 284, 285. Luidia, 145. Lumbricidce, 182. Lutrtbricus, 183. Lutra, 537. Lutraria, 285. Lyencephala, 484. Lynx, 541. MACACUS, 556. Maccaw, 458. Macellodon, 413. Machairodus, 567. Maclurea, 296, 313. Macraiichenia, 569. Macrobiotidce, 225. Macrodactyli, 448. Macropodidce, 493. Macrospondyhis, 415. Macrotherium, 564. Macrura, 214; characters of, 214-217. Mactra, 285. Mactridce, 284, 285. Madreporidce, 134. Madreporiform tubercle ofEchinodermata, 137 ; of Echinoidea, 139 ; of Asteroidea, 145 ; of Ophiuroidea, 147 ; of Holothur- oidea, 154. Malacodermata (Zoantharia), 111, 129. Malacopteri, 360. Malacopterygii, 358. Malacostraca, 198; characters of, 211. Mallophaga, 242. Malpighian tubes, of Insects, 237. Mammalia, 337, 338 ; general characters of, 471-483; osteology of, 472-480 ; teeth of, 479, 480 ; digestive system of, 481 ; circulatory system of, 481 ; respiratory system of, 481 ; nervous system of, 482; reproductive system of, 482; integu- mentary system of, 483 ; primary di- visions of, 484, 485 ; orders of, 484-486 ; distribution of, in time, 559-570. Mammoth, 528, 529, 567. Manatee, 472, 502, 503. Manatidce, 503. Manatus, 503. Mandibles, of Lobster, 196; of Arachnida, 222; of Myriapoda, 232; of Insecta, 235, 236 ; of Cephalopoda, 300, 308; of Verte- brates, 330. Manidce, 501. Manis, 479, 483, 498, 501. Mantle, of Tunicata, 266 ; of Brachiopoda, 272 ; of Lamellibranchiata, 280 ; of Gas- teropoda, 287 ; of Cephalopoda, 299 ; of Nautilus, 308. Maimbrium, 82, 96. Marginal bodies, of Medusae, 96 ; of i«- cernarida, 99, 104. ' Marginella, 294. Marmoset, 554. Marmot, 546. Marsipobranchii, general characters of, 355-357; families of, 355; distribution of, in time, 378. Marsupial bones, 477, 489, 492. Marsupialia, 484, 485,486; general char- acters of, 491 ; families of, 492-497 ; dis- tribution of, in space, 491 ; in time, 560. Marsupites, 156. Mastax, 173. * Mastodon, 527, 529, 566. Maxillae, of Lobster, 196; of Arachnida, 222 ; of Insecta, 236. Maxillipedes, of Lobster, 196; of Centi- May-flies, 244. Meandrina, 119. Measles, of Pig, 163 ; of Ox, 163. Medusidce, 95-99 ; structure of, 96 ; exact nature of, 97, 98. Megaceros, 523, 565. Megaderma, 549. Megalonyx, 563, 569. Megalosaurus, 421. Megalotrocha, 173. Megaptera, 508. Megatherium, 563, 569. Melania, 295. Melaniadce, 292, 295. Meleagris, 454. Meleagrince, 454. Meles, 536. Melicerta, 173, 174, 175. Melidce, 536. Meliphagidce, 462. Mellivora, 536. Membrana nictitans (of Birds), 439 ; of Mammals, 483. Menobranchus, 385, 386. Menopoma, 385, 386, 392. Mentum, 236. Mephitis, 537. 614 INDEX. Mergulus, 445. Mcropidce, 463. Merostomata, 198 ; characters and divi- sions of. 209: distribution of. in time. 220. Merulidce, 461, 462. Merycotherium, 569. Mesenteries (of Actinozod), 110, 112, 113, 115, 127. Mesopodium, 287, 293. Mesothorax, 234. Metamorphosis, 33 ; of Myriapoda, 231 ; of Insecta, 239; incomplete, 239; com- plete, 240. Metapodium, 287, 293, 297. Metasoma, 299, 307. Metastoma, of Lobster, 216 ; of Euryp- terida, 210, 211. Metathorax, 234. Microconchus, 188. Microlestes, 559, 560. Milwla, 51. Miliolida, 54. MUleporidce, 134. Millipedes, 230, 232. Mites, 221. Mitra, 294. Modeeria, 97. Modiola, 284. Mole, 474, 477, 483, 550. Mollusca, 14 ; general characters of, 253- 257 ; digestive system of, 253 ; circula- tory system of, 254 ; respiratory organs of, 254 ; nervous system of, 255 ; sense- organs of, 255 ; reproduction of, 255 ; shell of, 255-257 ; divisions of, 257 ; dis- tribution of, in time, 275, 312. Mollusca Proper, 257 ; characters of, 278 ; divisions of, 278 ; distribution of, in time, «2. uscoida, 257 ; characters and divisions of, 258 ; distribution of, in space, 275 ; in time, 276. Monads, 35, 36. Monitor, 411. Monkeys, 475, 476, 482, 483. Monodelphia, 485. Monodon, 511. Monomerosomata, 224, 225. Monomyaria, 283. Monostega, 54. Monothalamia, 52. Monotremata, 473, 474, 482, 484, 485, 486; general characters of, 489 ; distribution of, in space, 490 ; in time, 560. Mopsea, 133. Morphology, 11. Morse, 533. Mosasaurus, 413. Moschidce, 520, 522. Moschus, 522. Motacillince, 462. Mother-of-pearl, 256. Moths, 247. Mud-fish, 375. Mugilidce, 363. Mulleria, 284. Multivalve shells, 256, 286, 290. Murchisonia, 295. Murex, 294. Muricidce, 291, 294. Muridce, 544, 545. Mus, 545. Musca, 247. Muscicapidce, 461. Musk-deer, 520, 522. Musk-ox, 526. Mustela, 536. Mustelidce, 536. Mutilata, 503. Mya, 283, 285. Myacidce, 284, 285. Mycetes, 555. Mylodon, 563, 569. Myochama, 285. My odes, 545. Myopotamus, 543. My ox idee, 545. Myoxus, 545. Myriapoda, 191 ; general characters of, 230 ; development of, 231 ; distribution of, in time, 232. Myrmecobius, 495, 496. Myrmecophaga, 479, 501. Myrmecophagidce, 501. Myrmeleo, 244. Mytilidce, 283, 284. Mytilus, 284. Myxine, 356, 357. Myxinidce, 355. Myxinoids, 352, 356. NACREOUS shells, 256. Naididce, 182, 183. Nais, 183, 188. Naja, 406. Narwhal, 510, 511. Nassa, 294. Nasua, 535, 536. Natatores, 442; general characters of, 443, 444. Nathetes, 413. Natica, 294. Naticidce, 292, 294. Nautilidce, characters of, 309 ; sections of, 312; distribution of, in time, 314. Nautiloid shells (of Foraminifera), 53, 54. Nautilus, Paper, 299; shell of, 303; Pearly, 299 ; anatomy of, 307'; shell of, 304. Nebalia, 220. Nectocalyces, 89 ; structure of, 90 ; in Calycophoridce, 90 ; in Medusidce, 96 ; distinguished from the umbrella of Lucernarida, 99. Nectosac, 90. Needham, moving filaments of, 302. Nematelmia, 158 ; characters of, 168. Nematocysts, 76. Nematoda, 158, 168; characters of, 169 ; parasitic forms of, 169-171 ; free forms of, 171. Nematophores, 87. Nemertes, 167. Nemertida, 159 ; characters of, 167 ; de- velopment of, 167. Nereidcn, 188. Nereidea, 185. Nereis, 189. Nerita, 295. Neritina, 295. Neritidce, 292, 295. Nervures, 234. Neuropodium, 179. INDEX. 6l5 Neuroptera, 244, 252. Newts, 386, 387. Nidaruental ribbon, 255. Noctiluca, 72. Nodosaria, 52, 53. Nothosaurus, 418. Notidanus, 380. Notochord, 323, 325. Notommatina, 175. Notonecta, 243. Notopoclium, 179. Notornis, 449. Nucleobranchiata,- 291 (see Heteropoda). Nucleolus of Paramoecium, 67. Nucleus of Protozoa, 42 ; of Amoeba, 47, 48 ; of G-regarina, 44 ; of Paramcecium, 67 ; of Vorticella, 69 ; of Echinoder- mata, 145 (see Madreporiform tubercle) ; of the shell of Mollusca, 256, 289. Nudibranchiata, 256, 288 ; characters of, 292 ; divisions of, 296. Numenius, 450. Numida, 454. Nummulites, 53, 56, 57. Nummulitic Limestone, 57. Nycticebidce, 553. Nymph, 239. Nymphon, 225. ; 275. Oceanic Hydrozoa, 89 ; divisions of, 89 ; distribution of, in space, 108. Ocelli, of Medusce, 97; of EcMnoidea, 139; of Asteroidea, 146; of Planarida, 167 ; of Rotifera, 175 ; of Annelida, ISO ; of Chcetognatha, 189 ; of Limulus, 209; ofArachnida, 224; of Myriapoda, 231 ; of Insecta, 238 ; of Tunicata, 255, 268 ; of Lamellibranchiata, 255. Octopoda, 305, 311. Octopodidce, 305. Octopus, 302, 303, 311. Oculinidce, 134. Odontaspis, 380. Odontoceti, 505, 509. Odontophora, 278, 286. Odontophore, 287. Oedicnemus, 450. *0ldhamia, 108, 276. Oligochceta, 182, 188. OZiwa, 294. Ommastrephes, 311. Omnivora (Ungulata), 516. Onchuna, 199. Onchus, 379. Oncidiadcv, 294, 296. Oncidium, 296. Oniscus, 213. Onychoteuthis, 300, 311. Opemilata, 294, 296. Operculum, of Balanidce, 202 ; of Gaster- opoda, 287 ; of Heteropoda, 293 ; of Pteropoda, 297 ; of Fishes, 344, 349. Ophidia, 397 ; general characters of, 402- 405 ; divisions of, 405 ; distribution of, in time, 407. Ophidobatrachia, 384. Ophiocoma, 157. Ophioderma, 157. Ophiolepis, 147. Ophiomorpha, 384. Ophiura, 147, 14*. Ophiuridea, 148. Ophiuroidea, 137, 138 ; general characters of, 146 ; families of, 148 ; distribution of, in space, 155 ; in time, 157. Opisthobranchiata, 291, 292, 296. Opisthoccelia (Crocodilia), 415. Opossum, 495, 496. Orang-outang, 557. Orbitoides, 57. Orbitolites, 53. Greasier, 157 Organ of Bojanus, 273, 282. Organ-pipe Coral, 120. Organs of the mouth of Insects, 235, 236. Ornithodelphia, 485, 489. Ornithorhynchus, 479, 482, 485, 489, 490. OrMis, 274. Orthisina, 274. Orthoceras, 310, 211, 312, 314. Orthoceratidce, 312, 314. Orthoptera, 242, 243, 244. Orycteropidoe, 501. Orycteropus, 498, 501. Oscula, of Sponges, 60, 61 ; of Tape-worm, 161. Osteolepis, 367, 378. Ostraciontidce, 363. Ostracoda, 198 ; characters of, 205 ; dis- tribution of, in time, 220. Ostracostei, 368. OsZrea, 283, 284. Ostreidce. 283, 284. Ostrich, 451, 452. Otaria, 533. OttdO!, 450. Otter, 537. Oudenodon, 419. Ovarian vesicles, of Sertularida, 87. Otfibos, 526. Owidce, 524, 525. Ovipositor, 235, 249. Ovis, 525. Ovulum, 294. Owls, 464, 465. Oxen, 518, 520, 525. Oxyuris, 170. Pachydermata, 511, 512. Paddle-fish, 368. Pcecilopoda, 209 (see Xiphosurd). Paguridce, 217. Palceaster, 157. Pt'lcjechinus, 157. Palceocoryne, 108. Palceodiscus, 157. Palceophis, 407. Palceospongia, 64. Palocotherium, 515, 564. Palapteryx, 470. Pali (Corals), 115. Pallial line, 280, 281. Pallial sinus, 282. Palliobranchiata, 270. Pallium (see Mantle). Paludicella, 263. Paludicellea, 265. Paludina, 295, 313. Paludinidce, 292, 295. Paludomus, 295. Palythoa, 117. Pamphagus, 49. Pangolin, 501. 6i6 INDEX. Panopea, 285. Panspermy, 35. Pantopoda, 225. Paper Nautilus, 299, 303. 305. Papio, 556. Paradiseidce, 460. Paramcecium, 66; structure of, 66, 67; reproduction of, 07. Parapodia, 179. Parince, 462. Parmacella, 296. Parmophorus, 295. Parra, 458. Parrakeets, 458. Parrots, 457. Parthenogenesis, 30-32; of Ostracode Crustaceans, 205 ; of Insects, 30-32, 250. Passerine Birds (Passeres), 458. Patagium, 420, 488, 546. Patella, 289, 295. Patellidoe, 292, 295. Pavo, 455. Pavonince, 454. Peaehia, 112, 127. Pearly Nautilus, 299, 300, 303, 304, 307. Peccary, 517, 569. Pecten, 283, 284. Pectunculus, 284. Pedicellarise, 140. Pedicellina, 263. Pedicellinea, 265. Pediculus, 242. Pedipalpi, 227. Pelagia, 100, 101, 105. Pelagidee, 100, 101 ; structure of genera- tive zooids of, 103. Pelias, 405. Pelicanidee, 446. Pelonaia, 256. Pen, of Cuttle-fishes, 303. Penguin, 444. Peniculns, 199. Pennatula, 121. Pennatulidce, 120, 122, 123 ; distribution of, in time, 133. Pentacerotidce, 146. Pentacrinus, 149, 150. Pentamerus, 274. Pentastomida, 225. Pentatoma, 243. Pentremites, 153, 156. Perameles, 495. Perchers, 458. Percidce, 363. Perdix, 454. Perennibranchiala (Amphibia), 381, 382, 383. Perforata(Foraminifera\51, 54; (Corals), 118. Pericardium, of Crustacea, 191, 197 ; of Nautilus, 309. Periderm, 87. Peridinium, 72. Perigastric space, ofPolyzoa, 263. Periostracum, 257. Perischoechinidce, 157, Perissodactyla, 513. Peristome, of Vorticella, 68 ; of the shell of Gasteropoda, 290. Peristomial space of Actinia, 112. Peritoneum (Tunicata), 267. Peri visceral space,of Actinozoa, 110. Petaurus, 495. Petraster, 157. Petromyzon, 357. Petromyzonidce, 355. Petrospongiadce, 64. Pezophaps, 456, 470. Pezoporince, 458. Phacochcerus, 517. Phcenicopteridce, 447. Phcenicopterus, 447. Phalacrocorax, 446. Phalangers, 494, 495. Phalangidce, 227. Phalangistidce, 495. Pharyngobranchii, 353-355. Pharyngognathi, 363. Pharynx of Ascidians, 267, 268, 269; of Lancelet, 354. Phascolarctos, 494. Phascolomys, 492. Phascolotherium, 560, 561. Phasianidce, 454. Phasianus, 454. Pheasant, 454. Philine, 296. Phillipsia, 220. Phoca, 533. Phoccena, 510. Phocidce, 532. Pholadidce, 256, 286. Pholadomya, 285. P/iotas, 283, 286. Phorus, 295. Phosphorescence of the Sea, 72. Phragmacone, 256 ; of Spirilla, 313, 306 ; of Belemnite, 307. Phragmoceras, 312. Phryganeidce, 244. Phylactolcemata, 265. Phyllidia, 296. Phyllidiadce. 292, 296. Phyllirrhoe, 296. Phyllirrhoidce, 292, 296. Phyllocyst, 90. Phyllopoda, 198 ; characters of, 207 ; dis- tribution of, in time, 220. Phyllostoma, 549. Phyllostomidce, 548, 549. Phyogernmaria, 94. Physa, 296. Physalia, 76, 93. Physaliadce, 94. Physeter, 509. Physeteridce, 509. Physiology, 12. Physophora, 93. Physophoridce, 89 ; characters of, 92, 93 ; tentacles of, 93 ; reproduction of, 93 ; distribution of, in space, 108. Physostomata, 360. Picidce, 457. Pigeons, 455. Pigment-spot, of Infusoria, 71 ; of .fio£i- /era, 175. Pileolus, 295. Pileopsis, 295. Pilidium, 167. Pmna, 283, 284. Pinnigrada, 531. Pinnipedia, 531. Pinnoctopus, 311. Pipe-fish, 364. INDEX. 6l7 Pipidce, 390. Pisces, 337, 338; general characters of, 340 ; scales of, 340 ; skeleton of, 341- 345; limbs of, 345; tail of, 348; diges- tive system of, 351 ; respiratory system of, 349; heart of, 350; swim-bladder of, 351 ; nervous system of, 352 ; repro- ductive system of, 352 ; orders of, 353- 377 ; distribution of, in time, 377-380. Placenta, 472, 484. Placentalia (Mammalia), 484. Placodus, 419. Placoganoidei, 367, 368, 378. Placoid (scales of Fishes), 341, 370. Placoidei, 370. Plagiaulax, 560, 562. Plagiostomi, 370, 371 ; characters of, 372- 374. Planarida, 166, 167, 176. Planorbis, 289, 296. Plantigrada, 531, 534. Planula, 101. Plastron, 398, 399. Plataleadce, 450. Platanista, 511. Platyelmia, 158, characters of, 159. Platyrhina, 552, 554. Plecotus, 548. Plectognathi, 363. Plesipsauria, 417. Plesiosaurus, 418. Pleura, of Lobster, 194 ; of Trilobite, 209. Pleur acanthus, 380. Pleurobrachia, 124; ctenophores of, 125; canal system of, 125, 126 ; development of, 127 ; homologies of, 127. Pleur obrachiadce, 128. Pleurobranchiadce, 292, 296. Pleurobranchus, 296. Pleuronectidce, 362, 373. Pleuronema, 72. Pleurotoma, 294. Pleurotomaria, 295. Pliolophus, 564. Pliopithecus, 568. Plotus, 446. Plough-share bone, 427. Plumaster, 157. Plumularia, 87. Pluteus, 137, 138. Pneumatic filaments of Physophoridce, 93. Pneumatocyst, 92. Pneumatophore, 92, 93, 94. Pneumodermon, 298. Podophthalmata, 198 ; characters of, 213. Podosomata, 225. Podura, 235, 242. Polyarthra, 175. Potycaelia, 133. Polycystina, 58, 59. Polydesmus, 232. Polygastrica (of Ehrenberg), 67. Polynoe, 186. Polypary, 77, 81. Polype, 110. Polypide, 259, 260. Polypidom, 77. Polypite, 77. Polypterus, 367. Polystome Infusoria, 71. Polythalamia (Foraminifera), 52. Polytrema, 56. Polyxenia, 97 Polyzoa, 253, 254, 255 ; characters of, 258- 265 ; distinctions from Hydrozoa, 258, 259 ; typical polypide of, 260 ; avicularia of, 261 ; lophophore of, 263 ; nervous system of, 263; digestive system of, 263 ; reproduction of, 264 ; statoblasts of, 264 ; development of, 265 ; relations to Tunicata, 269 ; divisions of, 265 ; orders of, 265 ; distribution of, in space, 275 ; in time, 276. Polyzoarium, 258, 259. Pontobdella, 188. Porambonites, 274. Porcellanous shells, 256, Porcellia, 313. Porcupine, 544. Pores of Sponges, 60, 61. Parties, 132. Poritidce, 134. Porpoise, 505, 510. Portuguese man-of-war, 76, 89, 93. Potamides, 295. Poulpe, 302, 305. Praya, 91. Prayidce, 92. Pressirostres, 448, 450. Prestwichia, 220. Priapulacea, 179. Pristis, 374. Proboscidea, 484, 487; characters of, 527; distribution of, in time, 566, 567. Proboscis, of Medusae, 96 ; of Crinoidea, 149; of Planarida, 167; of Acantho- cephala, 168 ; of Gephyrea, 178 ; of Errantia, 186 ; of Lepidoptera, 236 ; of Proboscidea, 527. Procellaridce, 445. Proccelia (Crocodilia), 414, 415. Procyon, 535. Producta, 275. Productidce, 275, 276. Proglottis, 160. Pro-legs, 249. Promeropidce, 462. Pro-ostracum, 30t>, 307. Propodite, 196. Propodium, 287, 293. Proscolex, 161, 162. Prosimice, 553. Prosobranchiata, 291 ; divisions of, 291, 294. Prosoma, 299, 307. Prosoponiscus, 220. Prostomium, of Planarida, 167 ; of An- nelides, 180. Protaster, 157. Proteles, 538. Proteolepas, 204. Proteus, 336, 385, 390. Proteus-animalcule, 47. Prothorax, 234. Protoplasm, 4. Protopodite, 196. Protopteri, 375 (see Dipnoi). Protornis, 469. Protovirgularia, 133. Protozoa, 14 ; general characters of, 42, 43 ; classification of, 43, 44. Proventriculus, of Earthworms, 183 ; of Birds, 434. Proximal, 77. 6i8 INDEX. Psammobia, 285. Pseudembryo, 138. Pseudobranchia, 366. Pseudohsemal system, ISO. Pseudo-hearts, 273. Pseudonavicellse, 45. Pseudopodia, 43, 46, 48. Pseudoscorpionidce, 227. Psittacidce, 457, Psolus, 158. Psorospermice, 46. Ptarmigan, 454. Pteraspis, 369, 378. Pterichthys, 368, 378. Pteroceras, 294. Pterodactyles, 419, 420. Pteromys, 546. Pteropidce, 549. Pteropoda, 253, 286; general characters of, 297, 298; foot of, 297; shell of, 297; di- visions of, 298; distribution of, in space 298 ; in time, 313. Pteropus, 549. Pterosauria, 397; general characters of, 419 ; distribution of, in time, 420. Pterygotus, 210, 211. Ptilodictija, 276. Ptilograpsus, 106. Ptilopora, 276. Ptychoceras, 310, 315. Pulicidce, 246. Pulmogasteropoda, 288, 290. Pulmonaria (Arachnida), 224, 227. Pulmonifera (Mollusca), 290, 293, 296. Puma, 541. Pupa, 239, 240. Pupa, 296, 313. Pupina, 297. Purples, of Wheat, 172. Purpura, 294. » Pycnogonum, 225. Pygidium, 208. Pyramidella, 295. Pyramidellidce, 292, 295. Pyrosomidce, 270. Pyrula, 294. Python, 402, 406. QUADRATE Bone, 330, 402, 404. Quadrumana, 475, 476; 478, 484, 488; characters of, 552 ; sections of, 552 ; dis- tribution of, in time, 568. Quagga, 515. BABBIT, 542, 543. Racoon, 535. Radiata, 74. Radiolaria, 57; characters of, 58. Radiolites, 284. Raia, 374. Rallidce, 448. Rallus, 449. Ramphorhynchus, 419, 421. /tawa, 390. Ranidoe, 390. Raptores, 443 ; characters of, 464 ; sections of, 468. Rasores, 443 ; characters of, 453 ; sections of, 453. Rastrites, 106. Rat, 545. Ratel, 536. Ratitce, 442. Rays, 370, 373, 374, 380. Red Coral, 122, 129. Regnum Protisticum, 7. Rein-deer, 522, 523, 565. Reproduction, general phenomenaof,23-33; sexual, 23; non-sexual, 24-33. Reptilia, 337, 393 ; general characters of, 393-397; jaw of, 394; teeth of, 395; cir- culation of, 396; respiration of, 397; orders of, 397. Respiratory tree, of Holothurians, 154. Respiratory tubes, of Rotifera, 174. Reticulosa, 51, 53 (see Foratrtmifera). Retiolites, 106. Reversed shells, 257. Rhabdoccela, 167. Rhabdoidea, 54. Rhabdopleura, 106, 263. Rhamphastidce, 457, 458. Rhea, 452. Rhinoceridce, 513, 565. Rhinoceros, 512, 513, 514, 565. Rhino tophidce, 548. Rhinolophus, 549. Rhizocrinus, 150, 155. Rhizophysiadce, 95. Rhizopoda, 44 ; character^ of, 46 ; pseudo- podia of, 46 ; divisions of, 47. Rhizostoma, 104, 105. Rhizostomidce, 99; definition of, 101; de- velopment of, 101-103; structure of re- productive zooids of, 104, 105. Rhynchonelli , 274V 277. Rhynchonellidce, 272, 274. Rhynchosaurus, 419. Rhynchota (see Ilemiptera). Rhytina, 479, 503, 504. Ribbon-worms, 167. Rissoa, 295. Rodentia, 475, 484, 487; general characters of, 541 ; families of, 543; distribution of, in time, 568. Rorqual, 508. Rot, of Sheep, 165. Rotalina, 53. Rotatoria, 172 (see Roti/era). Rotifera, 135, 158; general characters of, 172 ; wheel-organ of, 173 ; water-vascular system of, 174; masticatory organs of, 173; affinities of, 176; vitality of, 5; dis- tinctions from Infusoria, 176. Round Worms, 169. Rugosa, 111, 124 ; characters of, 123 ; dis- tribution of, in time, 132; families of, 134. Ruminantia, 511, 512; characters of, 517; dentition of, 519; stomach of, 518; fa- milies of, 520; distribution of, in time, 565. Rupicapra, 525. SabeUa, 184, 188. Sagittd, 189. Salamanders, 386, 387, S92. Salamandra, 387, 390. Salmonidce, 361. Salpa, 269. Salpidce, 270. Sand-pipers, 450. Sand-worms, 181, 185. Sanguisuga, 181, 182. Sarcode, 42 ; characters of, 43. INDEX. 619 Sarcoids, of Sponges, 61, 64. Sarcoptes, 226. Sarcorhampus, 466. Sarsia, 28, 98. Sauria, 409. Saurillus, 413. Saurobatrachia, 384 (see Urodela). Sauropsida, 338, 393. Sauropterygia, 416; general characters of, 417 ; distribution of, in time, 418. Saururce, 441, 443; characters of, 467; distribution of, in time, 469. Saw-fish, 374. Saxicava, 286. Scalaria, 295. Scalpellum, 203. Scansores, 443 ; characters of, 457 ; fami- lies of, 457. Scaphites, 312, 314. Scaphognathite, 196. Scincidce, 410. Scincus, 411. Scissurella, 295. Sciuridai, 545. Sciurus, 545. Sclerenchyma, 115. Sclerobasica (Zoantharia), 113 ; divisions of, 116. Sclerobasic, corallum, 114, 115, 116. Sclerodermata (Zoantharia}, 117 ; divi- sions of, 118. Sclerodermic, corallum, 114, 115, 116, 117. Sclerogenidce, 363. Scolecida, 135 ; characters and divisions of, 158. Scolex, 161, 162. Scolites, 188. Scolopacidce, 450. Scolopendra, 232. Scomberidce, 363. Scorpion, 221, 222. Scorpionidce, 227 ; characters of, 227 ; dis- tribution of, in time, 230. Scyllcea, 296. Scyllaridce, 193. Scythrops, 457. Sea-anemones, 111, 129. Sea-cucumbers, 153. Seals, 531, 532. Sea-mouse, 186, 189. Sea- slugs, 292. Sea-spiders, 225. Sea-squirts, 8. Sea-worms, 177, 181, 185. Segmcntal organs, of Leeches, 182; of earth-worm, 183 ; of Errant Annelides, 186. Selachii, 370 ; characters of, 373. Semnopithecus, 556. Sepia, 307, 312. Sepiadce, 306, 312, 315. Sepiostaire, 303, 306. Septa, of Corals, 115 ; of the shell of Tet- rabranchiate Cephalopods, 309, 310. Seriatoporidce, 134. Serpula, 184, 185, 188. Sertularida, 79 ; characters of, 86 ; hydro- thecfe of, 86 ; polypites of, 87 ; reproduc- tion of, 87 ; development of, 87 ; distri- bution of, in space and time, 107, 108. Setse, of Annelides, 179, 183, 184, 186. Sharks, 350, 370, 373, 380. Sheat-fishes, 361. Sheep, 518, 520, 525. Shell, of Brachiopoda, 271 ; of Lamelli- branchiata, 279 ; of Gasteropoda, 289 ; of Heteropoda, 293 ; of Pteropoda, 297 ; of Argonauta, 304 ; of Nautilus, 304 ; of Tetrabranchiate Cephalopods, 309. Shrew-mice, 550. Shrikes, 462. Siamang, 557. Sigaretus, 294. Silicea (Sponges), 63. Siluridce, 361. Simia, 557. Simosaurus, 418. Sinupallialia, 284, 285. Siphonia, 65. Siphonida, 283, 2S4. Siphonophora, 78 ; characters of, 89 ; di- visions of, 89. Siphonostomata (Gasteropoda), 290, 291, 294, 313. Siphonotreta, 275. Siphons, of Lamellibranchiata, 281 ; of Gasteropoda, 288. Siphuncle, of the shell of Nautilus, 307, 308, 309 ; of Belemnites, 307 ; of Tetra- branchiata, 309; of Nautilidw, 309; of Ammonitidce. 310 ; of Orthoceras, 311. Sipunculacea, 179. Sipunculoidea,' 177. Sipunculus, 178. Siredon, 385, 386. Siren, 385, 395, Sirenia, 472, 473, 477, 484, 486 ; charac- ters of, 502 ; distribution of, in time, 564. Sirenidce, 385. Sitta, 462. Sivatherium, 524, 565, 569. Slimonia, 220. Sloth, 472, 486, 498, 499. Snakes, 397, 402, 403, 404, 405, 407. Solarium, 295. Solaster, 146. Solecurtus, 285. Solen, 285. Solenidce, 284, 285. Solidungula, 511, 512, 515, 565. Solipedia (see Solidungula}. Solitaire, 456. Solpugidce, 227. Somatic cavity, of Ccelenterata, 74, 75; of Eydrozoa, 76 ; of Hydra, 80 ; of Actin- ozoa, 109. Somatocyst, 89. Somite, 190; of Crustacea, 194; of Arach- nida, 221. Sorex, 550. Soricidce, 550. Soroidea, 54. Sparsispongia, 64. Spatangidce, 144. Spatularia, 368. Species, definition of, 19 ; origin of, 37-39. Spermatophores, 302. Sperm-whale, 505, 509. Sphceroma, 213. Sphceronectidce, 92. Sphcerozoum, 59. yhagodus, 379. ohargis, 401. " -.niscidce. 444. 620 INDEX. Spicula, of Sponges, 60, 63; of Radiolaria, 58, 60; ofActinozoa, 115, 121. Spider-monkey, 555. Spiders, 228, 229, 230. Spinax, 371. Spiniferites, 65. Spinnerets of Spiders, 229 ; of Caterpillars, 248. Spirialis, 298. Spirifer, 274. Spiriferidce, 274, 276. Spiriferina, 274. Spirorbis, 185, 188. Spirula, 303, 306, 312. Spirulidce, 306. Spirulirostra, 312. Splanchnoskeleton, 303. Spondylus, 284. Spongida, 60-65 ; skeleton of, 60 ; sarcoids of, 61 ; aquiferous system of, 61 ; repro- duction of, 62 ; classification of, 63 ; dis- tribution of, in space, 64; in time, 64; affinities of, 65 ; individuality of, 65. Spongilla, 47 ; reproduction of, 62, 63 ; sarcoids of, 64. Spoon-bill, 450. Spoon-worm, 177, 178. Spores, of Sponges, 63. Sporosac, of Corynida, 82. Spring-tails, 242. Squamae, of Aphrodite, 186. Squamata (Reptilia), 395. Squids, 304, 306. Squilla, 214. Squirrel, 545. Staggers, of Sheep, 163. Statoblasts, 26, 264. Stauridce, 134. Stauridia, 84. Steganodictyum, 65. Steganophthalmata (Medusae), 96, 101, 105. Stem-muscle, of Vorticella, 68. Stemmata (see Ocelli). Stenaster, 157. Steneosaurus, 415. Stentor, 9, 70, 71. Stephanoceros, 173, 175. Stephanomiadce, 94. Sterelmintha, 165. Stereognathus, 560, 561. Sternaspis, 178. Sternoptixince, 361. Sternum, of Crustacea, 194 ; of Arach- nida, 221 ; of Chelonia, 399 ; of Aves, 428 ; of Mammalia, 474. Stichostega, 54. Stigmata. ofPhysophoridce,Q3; of Leeches, 182; of Arachnida, 224; of Insecta, 238. Stolons, of Foraminifera, 52; of composite Actinozoa, 118; of social Tunicata, 255. Stomapoda, 198; characters of, 214; dis- tribution of, in time, 220. Stomatodendra, 104. Stork, 449. Strepsiptera, 251. Strepsirhina, 552, 553. Streptospondylus, 415. Strigidce, 464. Stringocephalus, 274. Strobila, of Rhizostomidce, 102 ; of Tceni- ada, 162. Strombidce, 255, 291, 294. Strombus, 294. Strophalosia, 275. Strophomena, 274. Strophomenidce, 274, 276. Struthio, 452. Struthonidce, 451. Sturgeon, 367, 368. Sturionidce, 368, 378. Sturnidce, 460, 461. Stylops, 250. Sub-brachiata, 362. Sub-kingdoms, 14. Suchosaurus, 415. Suctoria (Infusoria), 66, 71. Swcto, 516, 565. SWa, 446. Surinam Toad, 390. SMS, 517. Suspecta (Ophidia), 406. Swallow, 463. Swarm-spores, of Sponges, 63. Swifts, 463. Swim-bladder, of Fishes, 351. Swimmerets, of Lobster, 195, 196, 216. Swimming-bells, 90. Sylviadce, 461, 462. Synapta, 155. Synapticulse, 118. Synaptidce, 153, 155. Syndactyli, 463. Syndendrium, 104. Syngnathidce, 364. Syrinx, 178. Tabanidce, 247. Tabulse, of Corals, 117. Tabulata, 118, 133. T achy petes, 446. Tcenia, 160, 161, 162, 163, 164. Tceniada, JOI ; characters and develop- ment of, M2-1&4 Talitrus, 2l!P TWpa. 550. Talpidce, 550. Tank-worms, 171. Tantalince, 449. Tape-worm, 159, 160, 161, 162, 163, 164. Tapir, 513, 514. Tapiridce, 514. Tardigrada, 224, 225. Tectibranchiata, 292, 296. Teleosaurus, 415. Teleostei, characters of, 357-360 ; sub- divisions of, 360-364 ; distribution of, in time, 378, 380. Tellina, 285. Telllnidce, 285. Telson, of Crustacea, 192 ; of Lobster, 194 ; of Limulus, 209 ; of Scorpion, 227. Tentacles, of Hydra, 80 ; of Calycophoridce, 90 ; of Physophoridce, 93 ; of Medusidce, 96 ; , of Hydra-tuba, 101 ; of Actinia, 112; of Alcyonaria, 119; of Pleuro- brachia, 125 ; of Holothirroidea, 154 ; of Polyzoa, 258, 262; of Tunicata, 267; of Cuttle-fishes, 300, 306. Tentaculites, 188, 313. Tenthredinidce, 249, Tenuirostres, 460, 462. Terebella, 185 ; development of, 184. Trebratella, 274. INDEX. 621 Terebratula, 256, 272, 273, 274. Terebratulidce, 274, 277. Terebratulina, 274. Teredo, 286. Terguin, of the exoskeletou of Crustacea, 194 ; of Arachnida, 221. Terricola, 182 (see Oligochceta). Termites, 244 ; communities of, 245. Test, of Foraminifera, 50, 51 ; of Echin- oidea, 138, 142 ; of Tunicata, 266. Testacella, 256, 296. Testudinidce, 401. Testudo, 401. Tetrabranchiata (Cephalopoda), 304; characters of, 307 ; divisions of, 309 ; distribution of, in time, 314. Tetranychus, 226. Tetrao, 454. Tetraonidce, 454. Teuthidce, 306, 311, 315. Thalassarctos, 535. Thalassemacea, 179. Thalassicolla, 59, 60. Thalassicollida, 59. Theca, 298, 313. Theca, of sclerodermic corallum, 115. Thecaphora, 86, 88. Thecididce, 274. Thecidium, 274. Thecod-ontia, 415. Thecodontosaurus, 415. Thecosomata, 298. Thelyphonidce, 228. Theriomorpha, 387 (see .4noi«'a). Thoracica (Cirripedia), 198, 203. Thread-cells. 76. Thread-worms, 169, 170. Thylacinus, 497. Thylacoleo, 562. Thysanura, 242. Ticks, 225, 226. Tiger, 531, 539, 541. Tipula, 247. Toad, 390. Tongue, of Insects, 236 ; of Gasteropoda, 287 ; of Cephalopoda, 300 ; of Fishes, 344 ; of Snakes, 403 ; of Lizards, 409 ; of Crocodile, 414; of Birds, 433, 434, 440. Tornatella, 296. Tornatellidce, 292, 296. Torpedo, 374. Tortoise Encrinite, 156. Tortoises, 394, 395, 397, 401, 402. Tortrix, 402. Totipaimaice, 446. Toucan, 457, 458. Toxoceras, 310. Toxodon, 493. Tracheae, 223 ; of Arachnida, 223 ; of Myriapoda, 231 ; of Insecta, 238. Trachearia (Arachnida), 224. Trachyderma, 188. Trachynema, 98. Trachynemidce, 98. Transformation, 33. Trematis, 275. Trematoda, 158 ; general characters of, 164, 165 ; development of, 164 : habitat of, 164. Tremoctopus, 311 ; reproduction of, 302. Triarthra, 175. Trichecidce, 532, 533. Trichecus, 533. Trichina, 170. Trichocysts, 71. Triconodon, 560, 562. Tridacna, 285. Tridacnidce, 284. Trigonia, 284. Trigoniadce, 283, 284. Trilobita, 198, 2u7; structure of the crust of, 208 ; distribution of, in time, 220. Tringidce, 450. Trionycidce, 401, 402. Trionyx, 401. Triton (Mollusca), 294 ; (Amphibia), 387. Tritonia, 296. Tritoniadce, 292, 296. Trochilidce, 462. Trochoceras, 310, 312. Trochoid shell, of Foraminifera, 53 ; of Gasteropoda, 289. Trochus, 295. Troglodytes, 462, 557. Trogontherium, 568 Trophi, of Insects, 235, 236. Trophosome, 78. Truncated Shells, 257. Tube-feet of Echinus, 141; of Asteroidea, 145; of Ophiuroidea, 147 ; ofCrinoidea, 149 ; of Holothuroidea, 153. Tubicola, 181 ; characters of, 184 ; deve- lopment of, 184 ; distribution of, in time 188. Tubifex, 183, 188. Tubiporidce, 120, 124. Tubularia, 81, 85. Tubularida, 81 (see Corynida). Tubulosa, 118, 134. Tunicata, 254, 255 ; characters of, 265 ; respiratory process of, 268 ; circulation of, 268 ; reproduction of, 268 ; homolo- gies of, 269 ; divisions of, 270 ; distribu- tion of, in space, 276 ; in time, 276. Tunics, of Ascidians, 266. Turbellaria, 158; characters of, 166; di- visions of, 166. Turbinated Shells, 289. Turbinidce, 292, 295. Turbo, 295. Turkey, 454. Turrilites, 310, 311, 312, 315. Turritella, 291, 295. Turrit ellidce, 292, 295. Turtles, 398, 401. Tylenchus, 171. Tylodina, 296. Type, morphological, 14. UMBILICATED shell of Gasteropoda 290 Umbo, 256, 279. Umbrella, 296. Umbrella of Lucernarida, 99. Ungulata, 484, 487; characters of, 511-513; divisions of, 513-526; distribution of, in time, 564-566. Unto, 284. Unionidce, 283, 284. Univalve Shells, 256, 286, 289. Upupidce, 462. Uria, 445. Uraster, 146. Urnatella, 263. 622 INDEX. Urodela, 382 ; characters of. 384. Ursidce, 534. Ursits, 535, 568. Urus, 566. VACUOLES, of Protozoa, 47, 48 ; of Infu- soria, 67, 70. Vaginicola, 70, 71. Vaginulus, 296. Valkeria, 262. Valvata, 295, 313. Varanidce, 411. Varanus, 411. Varices, 290. Veil, of gonophores, 83 ; of nectocalyces, 90 ; of naked-eyed Medusae, 96. Velella, 94. Velellidce, 95. Venenosa (Ophidia), 406. Veneridce, 284, 285; distribution of, in time, 313. Venerupis, 285. Ventriculites, 64. Femts, 285. Venus' girdle, 128. Vermes, 135. Vermetus, 289, 295 Femtcidee, 198, 203; distribution of, in time, 219. Vertebra, structure of, 327-329. Vertebrata, 323 ; general characters of, 323-327 ; skeleton of, 327-332 ; digestive system of, 332 ; blood of, 334 ; respira- tion of, 335; nervous system of, 336; reproduction of, 337 ; development of, 324 ; divisions of, 337. Vesicle, contractile, of Protozoa, 43 ; of Amoeba, 48; of Paramoecium, 67; of Epistylis, 70. Vesicles, of Medusae, 96, 97. Vespidce, 250. Vespertilio, 548. Vespertilionidce, 548. Vibracula, 261. Vibrios, 35, 36. Viperina, 405, 407. Virgularia, 121. Visceral arches, of the embryo of Verte- brates, 326. Vitrea (Sponges), 63. Viverra, 537. Viverridce, 536, 537. Vogtia, 90. Valuta, 294. Volutidce, 291, 294. Vorticella, 66 ; structure of, 68 ; reproduc- tion of, 69. Vorticlava, 81. Vulpes, 539. Vulturidce, 465, 466. WAH, 535. Waldheimia, 274. Walrus, 531, 532, 533. Warblers, 461. Wasps, 249, 250. Water-hen, 448. Water-vascular system, of Annulnida, 135; of Echinoidea, 141 ; of Asteroidea, 145; of Ophiuroidea, 147 ; of Crinoidea, 151 ; of Holothuroidea, 154 ; of Scolecida, 158; of Tceniada, 159; of Trematoda, 164; of Turbellaria, 166; of Acantho- cephala, 168 ; of Nematoda, 169 ; of Rotifera, 174. Weasel, 536. Websteria, 133. Whales, 472, 473, 476, 479, 483, 504, 505. Wolverine, 536 Wombat, 492, 493. Wood-pecker, 457. Wrasse, 363 Wry-neck, 457. Xanthidia, 65. Xiphosura, 198; characters of, 209; dis- tribution of, in time, 220. XyloUus, 233. Xylophaga, 286. ZEBRA, 515. Zeuglodon, 564. Ziphius, 564. Zoantharia, 111; Malacodermata, 111, 129, 133 ; Sclerobasica, 113, 133 ; Scleroder- mata, 117, 124, 133. Zoanthidce, 113. Zoanthus, 113. Zoea, 218. Zonites, 313. Zooid, 78. Zoology, definition of, 1. Zootoca, 411. THE END. PRINTED BY WILLIAM BLACKWOOD AND SONS, EDINBURGH. 14 DAY USE RETURN TO DESK FROM WHICH BORROWED This book is due on the last date stamped below, or on the date to which renewed. Renewed books are subject to immediate recall. i AN 2n 1950 LD 21-100m-6,'56 (B9311slO)476 General Library University of California Berkeley