OiijjH THE LIBRARY OF THE UNIVERSITY OF CALIFORNIA PRESENTED BY PROF. CHARLES A. KOFOID AND MRS. PRUDENCE W. KOFOID OUTLINES Off COMPARATIVE ANATOMY. INTENDED PRINCIPALLY FOR THE USE OF STUDENTS. BY ANDREW FYFE. EDINBURGH: Printed by 7. Pillans & Sons, TOR ADAM BLACK, SOUTH BRIDGE STREET, EDINBURGH; AND THOMAS UNDERWOOD, 32. FLEET STREET, AND 40. WEST SMITHFIELD, LONDON. 1813. ADVERTISEMENT. THE Author thinks it necesssary to acknow- ledge here, that much of the information con- tained in the following Outlines is derived from modern Zootomists, particularly BLUMENBACH and CUVIER, whose works deserve to be care- fully perused by every one who proposes to make Comparative Anatomy a particular object of pursuit. ARRANGEMENT OF ANIMALS, ACCORDING TO THEIR ANATOMICAL STRUCTURE. ANIMALS are divided into, 1. Such as have a Vertebral Column and Red Blood; and, 2. Those which want Vertebra^ and have in general Colourless Blood. Vertebral Animals are subdivided into those with warm, and such as have cold Blood. In warm-blooded Animals, there are two classes, Mammalia and Birds. Cold-blooded Vertebral Animals consist also of two classes, Reptiles and Fishes. Invertebral Animals consist of Mollusca, Crustacea, Insects, JVormS) and Zoophytes. CLASS viii ARRANGEMENT OF ANIMALS, CLASS I. A, Vertebral warm-blooded Animals. MAMMALIA. In the Mammalia, the Females are viviparous, and suckle their young. The greater number of them are Quadrupeds, and these, for the most part, are covered with Hair, and walk on the Earth j the rest have a sleeked Skin, and inhabit the Ocean. They consist of the following Orders : 1. BIMANUM;. Two-handed, Thumbs separate on the Superior Extremities only. Homo, Man. / 2. QUADBUMANA. Four-handed, the Thumb or Great Toe capable of being opposed to the other Fingers or Toes on each of the four Extremities. Simi&i Apes, which have no Tails ; Baboons, which have short Tails; and Monkeys, which have long Tails. "Lemur, Makis or Macoucos, (a kind of link be- tween the Simiae and other Quadrupeds; hav- ing the hand-like Paw and flat Nail of the former, and the crooked Nail of the latter.) 5. BRADYPODA. Slow-moving Animals, with their Bo- dies generally covered by a hard crust. Some want the Incisor Teeth; others want the Incisors and Cus- pidati ; in others, the Jaws are (destitute of Teeth. Bradypug, or Sloth. Merme~ ARRANGEMENT OF ANIMALS. i*. Mermecopliaga,) Ant-eaters. Manis, Scaly Lizard, or Pangolin. Dasypus, Armadillos. OrnithorrynchuS) Duck-billed Animal. 4. CHEIROPTERA.- Having the Fingers elongated, for the expansion of Membranes which act as Wings. VespertiliOy Bat. 5. GLIRES, seu RODENTIA. Gnawing Animals, having large Incisors in each Jaw, by which they divide hard substances, Canine Teeth wanting. Sciurus, Squirrel. Glisy seu MyoxuSy Dormouse. MuSy Mouse and Rat. Marmota, Marmot. Cavictj Guinea Pig. Lepus, Hare and Rabbit. Jaculusy Jerboa. Castor, Beaver. Kangurus, Kanguroos. Hystrixy Porcupine. <3, FER^E. Predaceous and Carnivorous Animals; large Canine Teeth, the Molares forming pointed minences for tearing and cutting the Food. Erinaceusy Hedge-hog. Sorex 9 Shrew. Talpa, Mole. MeleSy Badges UrsuSy Bear. Didelphis, Opossum. Fiverra, Weasel, Ferret, Pole-cat, Civ^a Mustela, Skunk, Stoat, &c. Canis 9 Dog, Wolf, Jackal, Fox., Hyena. X ARRANGEMENT OF ANIMALS. JFelts, Cat, Lion, Tiger, Leopard, Lynx, Pan- ther, &c. Lutra, Otter. Phoca, Seal or Sea-calf. 7 SOLIDUNGULA, seu SOLIPEDA. A single Toe or Hoof on each Foot. Six Incisor Teeth in each Jaw. All herbivorous. Equus, Horse, Ass, Zebra, Quagga, &c. 8. PECORA, seu BISULCA, seu RUMINANTIA. Two Toes or Hoofs on each Foot. No Incisors in the Upper Jaw. All herbivorous, and ruminate the Food. Camelus, Camel, Dromedary, Lama. Ovis, Sheep. Capra, Goat. ^ntilope, Antelope, Chamois. Bos, Ox, Buffalo. Giraffa, Girraf or Camelopard* Cervus, Elk, Deer kind, Moschus, Musk. 9. BELLUJE, seu PACHYDERMATA. Animals of unshape- ly form, and tough thick hide. Have more than two Toes. Incisors in both Jaws. Some have enormous Tusks. * Sus, Pig, Pecari, Babiroussa. Tapir, Tapir. Elephas, Elephant. Rhinoceros, Rhinoceros. Hippopotamus, River-horse. Trichecusy seu Morse, Walrus, or Sea-cow. 10. CE * The Sus Scrofa Domestica of Linnaeus has undivided Hoofs. ARRANGEMENT OF ANIMALS. xi. 10. CETACEA. Whale kind, living in the Sea> and breathing through a hole on the top of the .Head. Bodies in the form of Fishes. Tail flattened hori- zontally. Monodon, Narwal, or Sea-unicorn. Bal&na, proper Whales. Physcter, Cachalot, Spermaceti Whales. jDelphinus, Dolphin and Porpoise. CLASS II. BIRDS. Birds are Oviparous ; have two Feet and two Wings. They have a horny Bill, and are covered with Feathers and Down. They form two divisions, Terrestrial and Aquatic. TERRESTRIAL BIRDS* 1. ACCIPITRES. Birds of prey, with strong hooked Bills and curved Talons. Vultur, Vulture. Falcoy Falcon, Hawk, Kite. Strix 9 Owl. Lanius, Shrike or Butcher Bird. 2. LEVIROSTRES. Light-billed Birds, having a large, light, hollow Bill. PsittacuSy Parrot kind. Ramphostos, Toucan. Buceros, Rhinoceros Bird. 3. PIOE, or Pies. Picus, Wood-pecker. xlf ARRANGEMENT OF ANIMAL*. Junx, Wry- neck. Sitta, Nuthatch. Alcedo, King's-fisher. Trochilus, Humming Birds. &c. &c. 4. COR ACES. Coraceous Birds, the character not de- fined. Corvus, Crow, Raven, Jackdaw, Magpie, Jay, &c. Coracias, Roller. Paradisea, Birds of Paradise. Cuculus, Cuckoo. &c. c. 5. PASSERES. Small Singing-birds, &c. something ia the form of the Passer, or Sparrow. Alauda, Lark. Sturnus, Starling. Turdusy Thrush, Blackbird. Emberiza, Bunting. Fringilla, Finches^ Canary Bird, Linnet, Spar- row. Motacitta, Nightingale, Red-breast, Wren. HirundO) Swallows, Martins, &c. Caprimulgus, Goat- sucker, &c. 6. GALLING. Gallinaceous Birds, mostly domesticat- ed ; possessing a large Crop and strong Muscular Gizzard. Columba, Pigeons. Tetrao, Grous, Quail, Partridge , Numiddy Guinea Fowl. Meleagris, Turkey. Pavo 9 ARRANGEMENT OF ANIMALS. xiil Pavo 9 Pea-fowl. Otisy Bustard. 7. STRUTHIONES. Struthious Birds. The largest of the class ; with Wings too small for flight. StruthiOy Ostrich. Casuarius, Cassowary. AQUATIC BIRDS. 1. GRALUE. Waders; frequenting marshes and streams ; long naked Legs ; long Neck ; cylindri- cal Bill of different lengths. Ardea, Crane, Stork, Heron, Bittern. Scolopax, Woodcock, Snipe, Curlew. TringUy Lapwing, Ruffs, and Reeves. Charadrius, Plover. Fidica, Coot. Eallusy Rail. PhanicopteruSy Flamingo. Tantalus, Tantalus, &c. 2. ANSERES. Swimming-birds ; web-footed. Bill broad and flat. Colymbusy Diver. Larus, Gull. Procellaria, Petrel, Diomedea, Albatross. Pelecanus, Pelican, Cormorant. Anas, Swan, Duck, Goose. Mergus, Merganser or Goosander. Alca y Auk, Puffin. Aptenodyta 9 Penguin. CLASS ARRANGEMENT' OF ANIMALS. CLASS III. B. Vertebral cold-blooded Animals. REPTILES. Their Body is covered with a Shell, or with Scales, or is quite naked. They have neither Hair, Mammae, Feathers, nor radiated Fins. They breathe through the Mouth and Nose by means of Lungs ; are ovipa- rous and amphibious. They are divided into Reptiles strictly so called, and Serpents. 1. REPTILIA. Having generally four, seldom two Feet. Testudo, Tortoise, Turtle. Rana 9 Frog, Toad. Lacerta, Lizards, Crocodile, Chaniaeleon, Newt, Salamander, Iguana, &c. 2. SERPENTIA. No Feet- Some are ovi-viviparous, having the Egg hatched in the Oviduct. Crotalus, Rattle-snake. Boa, huge Serpents of India and Africa. Coluber, Viper. Anguis, blind Worm. Amphisbtena, Amphisbaena. Cacilia, Cascilia. CLASS ARRANGEMENT OF ANIMALS. xv CLASS IV. FISHES. They possess Branchiae or Gills in place of Lungs, live in water, and do not breathe. Body scaly or naked. Have radiated Fins in place of Feet and Wings. They are divided into those with Cartilagi- nous, and such as have Osseous Skeletons. CARTILAGINOUS FISHES. 1. CHONDROPTERYGII. Having BranchiaB fixed, and no Gill-flap. Petromyzon, Lamprey. Gastrobranchus, Hag-fish. Raja, Skate, Torpedo, Stingray. Squalus, Shark, Saw- fish. Lopkius, Sea devil, Frog-fish. Balistesy File-fish. Chimcera, Sea-monster. 2. BRANCH IOSTEGI. Having Branchiae free, and a Gill-flap. Accipenser, Sturgeon, Beluga, Ostracion, Trunk-fish. Tetrodon^ Sun-fish. Diodon, Porcupine-fish. Cyclopterus, Lump-sucker. Centriscus, Trumpet-fish, Syngnathus, Pipe-fish. Pegasus, Pegasus. OSSEOUS xvi ARRANGEMENT OF ANIMALS, OSSEOUS FISHES. Osseous Fishes are arranged according to the situa- tion of their Fins. 1. APODES. No Ventral Fins. Murtena, Eel kind. GymnotuSy Electrical Eel. AnarrhichaS) Sea-wolf. Xiphias> Sword-fish. Ammoditesy Launce. Ophidium, Ophidium. Stromateus, Stromateus, Trichiums, Trichiurus. 2. THORACICI. Ventral Fins directly under the Tho- racic. Echeneis, Sucking Fish. CorypJicena^ Dorado. Zeus, Dory. Pleuronectesy Flounder, Plaice, Dab, Holibut, Sole, Turbot. Chatadorty Chaetadon. Sparus, Sparus. Percciy Perch. Scomber, Mackerel, Bonito, Tunny. Mullus, Mullet. &c. &c. 3. ABDOMINALES. Ventral Fins behind the Thoracic; chiefly inhabit fresh water. Cobitis, Loach. Silurus, Silurus. ARRANGEMENT OF ANIMALS. xvii Sahno, Salmon, Trout, Smelt. Esox 9 Garfish, Pike. Clupea, Herring, Sprat, Shad, Anchovy* Cyprinus, Carp, Tench, Gold-fish, Minnow, &c. 4-. JUGULARES. Ventral Fins in front of the Thoracic. Gadusy Haddock, Cod, Whiting, Ling. Uranoscopusy Star-gazer. Blennius, Blenny. Callionymus, Dragonet. Trachinus, Weaver. CLASS V. Invertebral and cold-blooded Animals. MOLLUSCA. Mollusca have soft fleshy Bodies, from which they derive their name. No articulated Members. Have a Heart and Blood-vessels ; Brain and Nervous System. Respire by means of Gills. Some are destitute of an external covering, and called Mollusca Nuda ; others are inclosed in a Shell, and termed Mollusca Testacea. When the Shell consists of one, two, or more separate pieces, it is called Univalvular, Bivalvular, and Multi- valvular. They are divided into the following orders: J . CEPHALOPODA. The Head surrounded by the Feet, which are the Tentacula. Sepia, Cuttle Fish. B Argonauta^ xviii ARRANGFMENT OF ANIMALS. Argonmita^ Paper Nautilus. Nautilus, Pearl Nautilus. 2. GASTEROPODA. The Head free. They crawl upon the Belly, which serves them as Feet. A consi- derable number are univalvuiar, or multivalvular. None are bivalvular. Limaxy Slug, or naked Snail. Aplysia, Aplysia. Doris, Sea Lemon, &c. a/o, Clio. Pat el la > Limpet. Helix, Snail. Haliotis, V r enus's Ear. Murexy Caltrop, or Rock-shell. Scrombus, Screw. Buccinum, Whelk. &c S. ACEPHALA. No distinct Head. Bivalvular. Ascidia, Ascidia. Thalia, Thalia. Ostrea, Oyster. Solen, Razor- shell. Cardium, Cockle. Mytdus, Muscle. &c. CLASS VI. CRUSTACEA. Crustacea possess a hard external covering, and nu- Rierous articulated Limbs. Antennae and Palpi. A Heart, ARRANGEMENT OF ANIMALS. xix Heart, with Circulating Vessels and Gills. A Nervous System. Cancer, Crab, Lobster, Cray-fish, Shrimp. Monoculus, having sometimes but one Eye, or two so close as to appear but one. CLASS VII. INSECTS. Insects have Antennae, Palpi, and articulated Limbs. Those which fly metamorphose, or pass through cer- tain changes in their Body, before they become com- plete Insects. They breathe by means of Tracheae, but have no Cellular Lungs. They have a Nervous System and Blood-vessels, but no Heart. They are divided into the following orders : 1. COLEOPTERA. Having a hollow horny Case, under which the Wings are folded. Scarab&us, Beetle. LucantiSy Stag-beetle. Dermestes, Dermestes. Coccinellcty Lady-bird. Curculio, Weevil. Lampyris, Glow-worm. Meloe, Spanish Fly. Staphylinus, Staphylinus. Forficula, Ear-wig. 2. HEMIPTERA. Four Wings, either stretched straight out, or resting across each other. Blatta, Coack roach. Gry Hits, Locust, Grasshopper. 2 Fulgora, xx ARRANGEMENT OF ANIMALS. Fulgora, Lantern-fly. Cimen, Bug. &c. 3. LEPIDOPTERA. Soft hairy Body, and four expand- ed Wings. Papilio, Butterfly. Sphinx, rtr , Moths. Phal&na, 4. NEUROPTERA. Four reticulated wings. Libellula, Dragon-fly. Ephemera, Ephemera, &c. 5. HYMENOPTERA. Generally possessing a Sting, Vespa, Wasp, Hornet. Apis> Bee. Formica, Ant. Termes, White Ant. Ichneumon, Ichneumon. &c. S. DIPTERA. Two Wings. JEstrus, Gad-fly. Musca, Common Fly. Culex, Gnat, Mosquito. Hippobosca, Horse Leech. &c. 7. APTERA. No Wings. Podura, Spring-tail. Pediculus, Louse. Pulex, Flea, Chigger. Acarus, Tick, Mite. Aranea, Spider. Scorpio, Scorpion. &c. CLASS ARRANGEMENT OF ANIMALS. xxi CLASS VIII. WORMS. Worms have neither Limbs, Antennae, nor Heart. Some have Circulating Vessels without Nerves ; others have both Vessels and Nerves. They do not metamor- phose. They may be divided into Internal, or such as inhabit the Bodies of other Animals, and External. 1. INTEENA. Some have distinct Vessels for carrying in their nourishment ; but few of them have any visible Nerves. Gordius, Guinea-worm, Hair-worm. Ascaris, Thread-worm, Round-worm. Trichuris, sen Tricocephalus. Fasciola, Fluke-worm. Ttenia, Tape- worm, Hydatis, Hydatid. 2. EXTERNA. Have Circulating Vessels; a Nervous Cord with Ganglia ; an elongated Body composed of Rings. , Aphrodita, Sea-mouse. Hirudo, Leech. Nereis, Nereis. Naisy Nais. Planaria, Planaria. LwnbricuS) Earth-worm. &c. B 3 CLASS xxii ARRANGEMENT OF ANIMALS, CLASS IX. ZOOPHYTES. Zoophytes, or Animal Plants, resemble Vegetables in their external structure, but are real Animals. The greater part of them are inhabitants of the Sea. They have the parts of their Bodies radiated, with their Mouth in the centre of the Radii. They have no articulated Limbs, nor Heart, though some have Ves- sels running from the Stomach through the Body. They have neither Brain nor Nerves. They consist of the following Orders: 1. ECHINODEKMATA. Covered by a hard and Coria- ceous Skin. Echinus, Sea- urchin or Egg. Asterias, Star-fish. Holothuria, Holotlmria. Sipunculus, Sipunculus. 2. GELATINOUS ZOOPHYTES. With Stomachs hollow- ed out in the Body. Medusa, Sea- blubber, Sea-nettle. Actinia, Sea-anemone. Hyara, Fresh- water Polypus. 3. INFUSORIA. Animalcula of Infusions. Vorticella, Wheel- animal. Brauhionus, Brachionus. Vibrio, Eel of Vinegar. Volvox, Volvox. Monas. c. 4. Zoo- ARRANGEMENT OF ANIMALS, xxiii 4. ZOOPHYTES strictly so called. The productions of Polypi, having a Medullary Body traversed by a Horny Substance, and the Branches terminated by the Polypi. Tubularia, Tubulated Coralline. Sertularia, Sea-moss. fee, 5. ESCHARA. Where each Polypus is contained in a Calcareous or Horny Shell, without any central Axis. Flustra, Mat weed. Corallina, Common Corallines. &c. 6. CERATOPHYTA. Where there is a Horny Axis, co- vered with a Fleshy Substance, from the cavities of which Polypi occasionally appear. Gorgonia , Sea- fan . Corallium, Coral. Pennatula, Feather- like Coralline, or Sea-pen. &c. 7. LYTHOPHYTA. In which there is a Stony Axis, with cavities serving as the Receptacles of, and formed by, Polypi. Madripora, Madripore. Millepora, Millepore. S. SPONGIA. With a Spongy, Friable, and Fibrous Substance. Alcinom, Alcionum. Sjuongia, Sponge. i? 4- CONTENTS CONTENTS OF THE FOURTH VOLUME. PART L OF MAMMALIA, 4*11 OF THE BONES IN GENERAL, 3 OF THE SKELETON, 4? BONES OF THE HEAD, 5 Os HYOIDES, - - 10 TRUNK, - 11 ANTERIOR EXTREMITIES, - - 16 POSTERIOR EXTREMITIES, - - 21 OF THE MUSCLES, - 25 COMMON INTEGUMENTS, - 41 BRAIN, 50 Of the Cerebral Nerves, - 55 Of the Spinal Marrow and Vertebral Nerves, 57 OF THE EYE, - 59 . EAR, - - 6* OF XXTI CONTENTS. Pag. OF THE NOSE, - 72 MOUTH and THROAT, with their Appen- dices, . 80 Lips, . ib. Tongue, ib. Salivary Glands, - - 82 Throat, . . 85 T?M, . 87 " HEART and BLOOD-VESSELS, - 98 ABSORBENTS, - . 104 - LARYNX, &c. - . 107 LUNGS, 113 STOMACH, . 107 - INTESTINES, . 122 - LIVER, PANCREAS, and SPLEEN, - 132 Liver, ib. Pancreas, - 135 Spleen, - - 136 ' OMENTUM, - 137 KIDNEYS, . 133 Renal Glands, - - 140 BLADDER, - - 142 - MALE ORGANS of GENERATION, 143 Testes, ib. Penis, - 148 FCMALE ORGANS of GENERATION, - 154 GRAVID UTERUS, - -' 157 " FOETUS, and Organs which nourish it for . some time, after Delivery, 161 PART CONTENTS. xxvii PART II. OF BIRDS. Pag. OF THE BONES, - 164? MUSCLES, - 171 INTEGUMENTS, - 1*76 BRAIN, &c. 180 Nerves, - 1 82 EYE, 183 EAR, 188 NOSE, - 190 MOUTH, THROAT, &c. 192 Tongue and Salivary Glands, - ib. HEART and BLOOD- VLSSELS, 195 ABSORBENT SYSTEM, - 196 ORGANS of VOICE and RESPIRATION, 19$ ALIMENTARY CANAL, - 204- Granivorous Birds, - - ib. Carnivorous Birds, 207 ASSISTANT CHYLOPOIETIC VISCERA, - 210 Liver, ib. Spleen, 211 Pancreas, 212 KIDNEYS, - ib, Renal Glands, 213 MALE ORGANS OF GENERATION, - ib. FEMALE ORGANS OF GENERATION, 215 PART CONTENTS. PART III. OF REPTILES. OF THE BONES, . . 222 - MUSCLES, - _ 227 - INTEGUMENTS, - . 231 - BRAIN, - 233 - EYE, - - 236 - EAR, - , - 237 - - NOSE, 239 ' MOUTH, - . 24*0 - HEART and BLOOD-VESSELS, - 242 - ABSORBENTS, - - 246 - - ORGANS of VOICE and RESPIRATION, 24-8 - - ALIMENTARY CANAL, - 251 - LIVER, PANCREAS, and SPLEEN, - 253 Liver, - - 253 Pancreas, - - 254 Spleen, * - 255 " KIDNEYS, - , ib. MALE ORGANS of GENERATION, - 257 - - ORGANS of APPREHENSION, - 259 - - FEMALE ORGANS of GENERATION, -^ ib. PART IV. OF FISHES. OF THE BONES, ... 262 - MUSCLES, . 266 OP CONTENTS. xxix Pag. OF THE INTEGUMENTS, - 267 - BRAIN, &c. 270 - - EYE, 276 - EAR, 280 - NOSE, - - 284 - TONGUE, - 285 - HEART and BLOOD-VESSELS, - 286 i ABSORBENT VESSELS, - 289 - ORGANS of RESPIRATION, - 292 - ALIMENTARY CANAL, - 293 - AIR-BAG, 296 - LIVER, &c. - 299 - URINARY ORGANS, - 301 - -- MALE ORGANS of GENERATION, 302 -- FEMALE ORGANS of GENERATION, - 304? PART V. OF MOLLUSCA, 307 Jaws Epidermis Muscles-- Nervous System Eye Organ of Hearing Organ of Smell Mouth Lips Tongue Salivary Glands CV- culating System Organs of Respiration Ali- mentary Canal Liver- Organs of Generation. PART VL OF CRUSTACEA, 320 Jaws Skin Muscles Feet Nervous System Organ of Hearing Organ of Smell Cir- culating System Organs of Respiration All* mentary CanalLiver* Organs of Generation. PART xxx CONTENTS, t PART VII. Pag. OF INSECTS, - - 326 Jarvs-^Lips Antennas Palpi Larvce -Muscles Body Members Epidermis Brain and Ner- vous -System Eye Ear Organs of Taste and Salivation Circulating SystemRespiratory Or- gans ^Alimentary Canal Liver, 8$c. Organs of Generation. PART VIII. OF WORMS, - 338 Epidermis MusclesNervous System Circulating System Intestinal Canal Organs of Generation. PART IX. OF ZOOPHYTES, - - 345 Skin * Teeth Muscles Nervous System Vascular System Organs of Respiration Alimentary Ca- nal and CavityOrgans of Generation. ERRATA. Page viii. Line 9 . for sleeked read, sleek 18. 3. from the foot, for Genera read Onders; 29. 2. from the foot, for in the Ape tribe, only read in the Ape tribe only, , , C for Solipeds, |6|6|1|0|6|6 97. 7. from the foot, ^ Soli P eds ; | 3 | 3 | 1 | | 6 | 6 168. 5. from the foot, for peculiar to read remarkable in ___ 195. 12. from the foot, for corresponds read corresponding 201. 11. from the foot, for Branches read Bronchi. . 212. Last Line, for conjoined read connected - 221. Line 11. for Vasa Vitelli and Lutea read Vasa Vitelli Lutea _ 295. 10. for Fossula read Fossulae 296. 15. from the foot, for Cyprius ; read Cyprins; ____ 344. 3. dele also - 344 ; 15 . dele The Ovarium, &c. to the end of the paragraph. PART I. or MAMMALIA OF THE BONES IN GENERAL, TttE Bones of all the Mammalia are nearly of the same colour and general appearance as those of the Human Body. In some, however, as the Dentes Mo- lares of the Elephant, and the larger Herbivorous Ani- mals, the colour is observed to vary in different parts of the same Bone. They are covered with a Periosteum, and contain Marrow, which in the Whale tribe is fluid. Ossification varies in rapidity in different Animals, and in different Bones of the same Animal. In the Internal Ear, it is complete sooner than in any other part, and the Bones of this Organ surpass all others in density. Bones acquire their complete formation sooner or later, according to the length of time at which the Animal attains its full growth. The Bones of some of the larger species are of a coarser texture than in the Human Body, especially those of the Whale tribe, in which the Fibrous Struc- ture is rendered very distinct by steeping them in water. A 2 Th* 4 OF THE BONES [PART L The Cetacea and Seal have no cavities even in their long Bones. The Horns of some Animals, as the Stag, are of the same nature with the Bones, but internally have neither Cavities nor Marrow. The component parts of the Bones of all Mammalia correspond in a great measure with those of the Human Body ; but their relative proportions are found to differ not only in the various Genera and Species, but in the different Bones of the same individual. The Horn of the Stag is similar to Bone, not only in its texture, but also in its component parts, in which there is a large- proportion of Gelatine. OF THE SKELETON. THE Skeleton of Mammalia is divided into Head, Trunk, and Extremities, the last of which, in Quadru- peds, owing to the horizontal situation of the Animal, are denominated Anterior and Posteriory the former corresponding to the Superior, the latter to the Inferior Extremities, of the Human Body. \_ BONES PART!.] OF MAMMALIA. BONES OF THE HEAD. Cranium. NEXT to the Human Species, the Ape tribe is found to have the largest Cranium in proportion to the Face ; but the Cranium is small here when compared with that of the Human Body. While, in a European Man y the Area of a longitudinal vertical section of the Cranium is almost four times larger than that of the Face, (the Lower Jaw excluded) ; in the Monkey it is little more than double. In most of the Ferae it is nearly equal. The Glircs y Solipeds, Pccora, and Bel- lu&y have it less. It is only about a half in Pecora, and little more than a fourth in the Horse ; and in pro- portion as the Cranium becomes less than the Face, the Animal is observed to become more stupid or fero- cious ; though to this rule there are many exceptions. The Facial Angle assists likewise in discovering the proportion between the Cranium and Face. It is more obtuse in the Human Species, and more acute as we descend in the scale from Man, till in the lower classes of Vertebral Animals it disappears. In the Human Adult European, the angle is 85 ; in the Ourang-out- ang 67 j in some of the other Monkeys, it goes as low as 30 ; and among the other Genera of Quadrupeds, it is in some only 20. The Temporal and Occipital Ridges, or Cristos, vary considerably in different Quadrupeds. They serve chiefly for the attachment of the strong Temporal and Cervical Muscles attached to them, and are most con- A 3 siderable $ OF THE BONES [PART I, sidcrable in Carnivorous Animals. The situation and direction of the Foramen Magnum Occipitis also vary considerably among some Animals. In most Quadru- peds it is placed obliquely at the extremity of the Cra- yiium, with its posterior edge turned upward. Ani- mals going upon all fours have the Occipital Foramen situated farther back, in proportion as the Face is, elongated ; to compensate for which the Head is sus- pended by strong Muscles, and also by the Liga- znentum Nuchse placed upon the upper part of the Keck. The Ape tribe, but more particularly the Ourang- puttuig, which forms a medium between Man, who walks erect, and Quadrupeds that move in the horizontal posture, have this passage nearer the centre of the base of the Cranium, than it is in any other Animal, in con- sequence of which they can support an erect posture longer than other Quadrupeds. The number of Bones here is in general the same as in Man ; but Ossa Triquetra are seldom seen. All the Ape tribe have eight distinct pieces. In the Perez, and many others, the Parietal Bones are united at an early period ; but in many Quadrupeds, particularly Horned Cattle, the Os Fronds is divided by the Sagittal Suture for a considerable time. In some, as the Ferae and Horse, there is only one Parietal Bone ; while in others they are joined by accretion to the Qs Occipitis. The Bones of the Cranium, in the Elephant, are soon iinited into one piece, ^o as to appear like a single Bone. In the Cetacea, the Parietal, Occipital, and Temporal Bones, are early united. In a great variety of the Ani? PART.] OF MAMMALIA. 7 i-nals of this class, the portion of the Os Temporis* containing the internal parts of the Ear, is separated from the rest of the Bone by a Suture. In the Cetacea, the connecting medium is so soft, that the parts can be yeadily removed from each other. In the order Glires or Rodentia, the Temporal Bone has no Carotic Canal, the Artery entering be- tween the Temporal and Sphenoid Bones. There is a considerable variety, also, among the other Foramina at the base of the Cranium ; those of the Cribriform Plate of the Ethmoid Bone being in number and size in proportion to the acuteness of smell. In the Cetacea, the Cribriform Plate of this Bone is wanting. The three large Fossae at the inside of the Base of the Cranium in Quadrupeds are more superficial as the Animal is removed from Man. In many Carnivorous Animals, the Cavity for the Cerebellum is separated from that of the Cerebrum by a broad Osseous Lami- na, projecting from the inner side of the Cranium. The Scull of the Elephant presents a remarkable ap- pearance ; the two Tables are separated from each other to a considerable distance, and the space is occupied by numerous Osseous Plates, that form large Cells, com- municating with each other, and then with the Eusta- chian Tube, which leads into the Throat. These Cells -are filled with air, which, without adding to the weight of the Head, allows it to be increased in size, for the attachment of the strong Muscles necessary for the .notion of the Lower Jaw and Proboscis. Jn the Cetacea, the Scull is very globular, and the A 4 Face 9 OF THE BONES [PART!. Face flat and small, the part analogous to the Nose be- ing upon the summit of the Head. Face. The size and form of the Face depends in a great measure on the figure and extent of the Upper Jaw. Quadrupeds, the Ape tribe not excepted, have two Bones in the Face in* addition to those found in Man These contain the roots of the Dentes Incisores, when such are present, but exist also in Animals destitute of Teeth. They are termed Ossa Intermaxillaria^ Ossa Incisoria, vel Labialia, and are situated between the Ossa Maxillaria ; but the Suture which separates these from the Maxillary Bones is obliterated in some Ani- mals at an early period of life. In the Ourang-outang, as well as Mammalia in general, the Jaws are longer than in the Human Body. The Elongation is produced by the depth and situa- tion of the superior Maxillary Bones, and increases in Quadrupeds in proportion as they recede from Man. "When standing in the ordinary or horizontal posture, the Head of the Quadruped is supported by Muscles, and by the Ligamentum Nuchse, which becomes strong- er according to the weight of the Head in general. The prolongation of the Bones of the Face may be determined by the Facial Angle, which becomes more acute according to the length of the Face. The Face of the Fer OF THE BONES [PART L this Bone is that of the Duck-bill appearance which it has in the OrnithorryncJius* Os HYOIDES. The Os Hyoides has the same parts in general as in Man. It can be divided into -Body and Cornua ; but in many Animals, the long Cornua are so united with the Body, as not to be distinguished from it. Those corresponding to the small Appendices in Man are here larger than the other Cornua, and, being articulated be- fore them, are distinguished by the name of Anterior , the other being called the Posterior. The first are fixed to the Styloid Process of the Temporal Bone, or to a slender Bone supplying its place. In the Qwang-outgngt the Os Hyoides is nearly as in Man, It varies in the other Apes. In the Carni- vora, it is generally long and slender. In the Solipeds, the Posterior Cornua and Body form an Arch, from which a long Process descends ; the Anterior Cornua are short, and are directed forward to b.e articulated >vith the Styloid Process. In Ruminants, the Posterior Cornua unite with the Body into an Arch, which has a Tuberosity in the middle of its inferior part ; the Anterior Cornua have each two pieces of unequal length, the short one being articulated with the Styloid Process. In Amphibious Quadrupeds, as the Seal, the Body of the Os Hyoides is slender ; the Posterior Cornua are continued in an Arch with the Body 5 the Anterior are (brined of three Bones, The PART!.] OF MAMMALIA. U The Cetacea have also their Os Hyoides ; with its An- terior and Posterior Cornua, which are of considerable length, and of a particular form. TRUNK. The Trunk in Mammalia, as in the Human Body, is divided by Anatomists into Spine, Pelvis, and Tho- rax, the first of which is the most constant part of the Skeleton. The Spine has the same number of Cervical Vertebrae in the different individuals of this class, as in the Human Body, excepting the three-toed Sloth, which, instead of seven, has nine. In the Ape tribe, the Cervical Vertebra differ from those in Man, chiefly in the Spinous Processes being proportionally stronger, and not forked. In the Ferte, the Spinal Holes are almost in the Bodies of the Verte- brae. The first and second Vertebrae in these Animals are remarkable, the former for the strength of its Transverse, the latter for that of its Spinous Pro- cesses ; these parts affording attachment to the powerful Muscles which correspond with the other parts in ena- bling the Animal to seize its prey, or defend itself. In the Armadillo, and other Animals of this order, the six last Cervical Vertebrae are in a manner soldered together, and have a kind of Groove in which the Eso- phagus is lodged. In the Cetacea, the Bodies of the Cervical Vertebrae are remarkably thin, and two or Three of them are frequently anchylosed. The Dorsal Vertebra in true Qitadruveds have the anterior 12 OF THE BONES [PART I. anterior Spinous Processes augmented, in proportion as the Head is heavy or joined to a long Neck, for the more advantageous attachment of the Muscles and the Ligamentuni Nucha^ We have examples of this in the EU'phant, Ox, and Camel, in which they are remark- ably long. The Lumbar Vertebrae vary much in number in the different species of this class, as will be seen in the Table annexed. The Spinous and Transverse Pro- cesses are directed forwards in the same angles ; as, for example, in the Dog and Cat. The size of the Trans- verse Processes is considerable in some, as the Ox and Horse, to give attachment to the strong Muscles of the Loins. The Os Sacrum varies more in appearance than either of the former sets of Vertebras j the number not being the same even in the different species of the same Ge- nus* It is generally narrower in proportion than in Man, but wider in such Genera as occasionally stand erect, as the Ape, Bear, &c. The Spinous Processes are longer in most of the Ferae than in Man. In most Huminants, they almost form a continued crest. In the greater part of the Ape tribe, it has one or two pieces fewer than in the Human Body. In the long-tailed Ape, indeed, there are six -, but in the Ou- rang-outang there are only three. In the Horse, it is remarkable for the long Lateral Processes at its anterior extremity. The Cetacea want the Pelvis^ of course the Sacrum. The Os Coccygis is extended to form the Tail, winch, in many Quadrupeds, consists of a great num- ber FART L] OF MAMMALIA. IS ber of pieces ; and these are of two kinds, one which has a Spinal Canal, and another in which there is no perforation. In such Apes as want Tails, this Bone is found to have at most three pieces ; but these are per- forated for the passage of the Spinal Marrow and Nerves. In other Quadrupeds, the Vertebrae of the Tail nearest the Sacrum are perforated for the Spinal Mar- row, and have Articular, Transverse, and Spinous Processes, while the other, diminishing gradually in. size to the end of the Tail, have only small Processes for the insertion of the Muscles. In Animals with prehensile Tails, as some of the Ape tribe, Opossum, &c. there are frequently small Pro- cesses, or even supernumerary Bones, for giving proper direction to the Muscles. In the Beaver, where the Tail is used as a Trowel, the Caudal Vertebrae are remarkable for the size of the Transverse Processes. The following Table gives the number of the Verte- brae found in a few of the Species of this Class. THE BON 7 ES SPECIES. 1 Cervical. I 1 "rt 12 a Lumbar. "3 s t/3 Caudal. Ourang-outang, 7 12 4 3 4 Other Apes, 7 11-14 3-8 1-6 3-32 Two-toed Sloth, 7 23 2 4 7 Three-toed do. 9 14 4 3 13 Bat, 7 11-12 4-7 i-4 0-12 Rat, 7 12-13 7 3-4 23-26 Mouse, 7 12 7 4 24 Hare, 7 12 7 4 20 Rabbit, - 7 12 7 2 20 Mole, 7 fs 6 7 11 White Bear, 7 13 6 7 31 Brown Bear, M 14 6 5 5 Weasel, - 7 14 6 3 14 Dog, Wolf, 7 7 13 13 6 7 3 3 22 19 Fox, 7 13 7 3 20 Cat, 7 13 7 3 22 Lion, 7 13 6 3 23 Tiger, 7 13 7 4 19 Otter, 7 14 6 3 21 Seal, 7 15 5 2 12 Horse, 7 18 6 2 17 Ass, ' 7 18 5 2 17 Mule, 7 18 5.6 2 17 Camel, 7 12 7 4 17 Sheep, 7 13 6 4 16 Goat, 7 13 6 4 12 Ox, 7 13 6 4 16 Deer, 7 13 6 3 11 Pig, 7 14 5 3 5 Elephant, 7 20 3 4 24 and upwards, and upward^. and upwards. Dolphin and Porpoise, in all 66, FART I/J OF MAMMALIA, is The Thorax of Animals without Clavicles is common- iy compressed externally, or is deeper from Spine t6 Sternum, than in the Human Species, especially in. long-legged Animals. The Ribs are present in all the individuals of this class. They vary in number in different tribes ; the greater number of Mammalia possess more Ribs than, are found in Man, though in a few the number is smaller. There is also considerable variety in the form ; in Herbivorous Animals, they are observed to be broad and thick. The Armadillo has the two first pairs very large in proportion to the rest. The two-toed Ant-eater has Ribs so broad as to overlap like the tiles of a house, and give the appearance of a coat of marl. The number of the Ribs on each side of the Thorax of Mammiferous Animals, corresponds with that of the Dorsal Vertebrae, and can therefore be readily known by examining the preceding Table. Sternum. This, in the Ourang-outang, is broad and flat as in Man, but in other Ape$ y and in many Mam- malia, it is narrow, of a roundish form, and composed of several moveable pieces, corresponding to the mo- tions of the Spine. In the Bat it is like a T, the fore part going across to be articulated with the Clavicles. The Mole has the Anterior Extremity prolonged be- fore the Ribs, to be joined to the Clavicles under the Neck, so as to give origin to strong Muscles of the An- terior Extremities, which assist the Animal in burrow- ing under the ground. The 36 OF THE BONES [PART L The Horse and Elephant have the Sternum flattened laterally. The Pig has it narrow before, but much enlarged posteriorly. ANTERIOR EXTREMITIES. The Anterior Extremities in Mammalia can be di? vkled nearly as the Superior Extremities of the Human Body, though in some of the individuals of the class, they vary considerably from the corresponding parts in TvTan. Most Quadrupeds want Clavicles, in consequence of which the Anterior Extremities come nearer each other* and their progressive motion is rendered easier. The Clavicles are found in all Quadrupeds which use their .Anterior Extremities much for other purposes than walking. They exist in the Ape tribe, and there they resemble those in Man. They are present also in the Batj where they are remarkable for their thickness and strength; in the Mole, Shrew* Hedge-hog, Squirrel, Eat, and Beaver, In the Dog, Cat, Weasel, Bear, Otter, Seal, Hare, there is only a Clavicular Bone, suspended in Flesh ; these Animals forming a sort of medium between the former and those that want Clavicles, such as, Solipeds, .Ruminants, Belluse, and the Cetacea. Scapula* This exist* in all the Mammalia* It differs in. PART L] OF MAMMALIA. I? in shape from that in Man, and its form varies consi- derably in different Animals. In the Ape and Elephant, the edge next the Spine is, as in Man, the longest ; in most other Quadrupeds, it is the shortest. The Coracoid Process is commbnly wanting, though present in many. In the Pig, the Spine of the Bone is almost effaced near the Humeral Extremity ; but about its middle, there is a large projecting Pro- cess. Arm.- In all Animals, the Os Humeri is single in each Anterior Extremity, as in the Human Arm, and becomes shorter as the Metacarpus is elongated. In Animals with a single Metacarpal Bone, the Os Humeri is deeply seated in the Fleshy parts of the Thorax. There is often a hole in a kind of Linea Aspera which projects in the Arm-Bone, and frequent- ly a perforation in the Bone where it receives the* Ole- cranon. In the Mole, the Os Humeri is peculiar, not only for its shortness, but in being articulated by one small head to the Scapula, and by another to the Clavicle'. It is altogether of such a nature as to turn the Palm out- wards, for working with the Hand. Fore-arm. The motions of Supination and Prona- tion are found in the Anterior Extremity of a few Ge- nera only, and these are chiefly for enabling the Ani- mals to lay hold of, or search for, their food. In Apes, the Bones have the same general appear- ance as in Man, but the Radius is the principal Bone* The Bat has no Ulna, or only the Rudiment of one. VOL. IV. B In U OF THE BONES [PART i In Carnivora, the Olecranon is extended farther back than in Man. In the Pig, Elephant, and some other Animals of similar shape, the Radius is placed entirely before the Ulna ; they move on a single pulley. In Solipeds and Pecora, the Ulna is only an Appen- dix of the Radius. In the latter, it is anchylosed with the Radius almost its whole length. In Solipeds, there is a Furrow, with a slit in the top. Hooved Animals have the Inferior Head of the Radius compressed, and the back of the Carpus turned forward. In the Ceta- cea, the Radius and Ulna have a flattened form. Hand. The Carpus in Apes has one Bone more than in Man. The Os Pisiforme is so prominent as to serve as a sort of Heel ; and the same thing happens in the Carnivora. In the Mole, besides nine Bones, at in the Monkey, there is a Falciform Bone, which gives the shovel-like form to the Hand. In Carnivora, the Scaphoid and Lunar Bones are joined into one piece. Rumhiants have four Bones in the first range. Most have two in the second. Solipcik have four in the first range, and three in the second. In Cetacea, the Bones of the Carpus are flattened, and joined together in the form of a pavement. Metacarpus. The number of the Bones here is in general equal to that of the Fore Toes, except in Soli- peds and Ruminants, where, in the former, the Meta- carpal Bone consisted originally of two pieces, and, in the latter, the two Metacarpal Bones are at an earlv age united into one piece. In both these Genera, this single piece is termed Canon or Shank Bone. In the Horse, the Canon Bone has a pair of much shoite- PART I.] OF MAMMALIA. 19 shorter pieces, called Sfyloid or Splint Bones, firmly attached to its posterior and lateral parts ; these have been considered also as Metacarpal Bones. In the Pig, the Metacarpus consists of four distinct Bones. In the Dog, Horse, Ox, Sheep, &c. where only the Toes touch the ground in supporting the Body, the Metacarpus forms the part commonly called the Fore. J^eg, the Carpus being termed the Knee. Toes. There are always from three to five Toes in Mammalia. All clawed Quadrupeds have five. Solipeds have one perfect, and two imperfect. Ruminants have two perfect, and two imperfect. Each perfect Finger or Toe has three Bones, ex- cept the Thumb or Great Toe, which has never more than two. The Metacarpus and first Phalanx are more curved towards the Palm, and the Phalanx on which the Nails are placed is always rounded, and more pointed than in Man. The Ape tribe have the Thumb separate, and opposed to the other Fingers, but always shorter than in the Human Species. In this respect, the Human Hand is superior to that of every other Animal. The different parts of the Hand are found in several individuals of this class, but less complete than in the Hand of the Human Body, the great superiority of which arises from the size and strength of the Thumb, which can oppose the Fingers in the various offices the Hand has to perform. In the Bat fribe, the Phalanges of the Fingers, be* B 2 tween ju OF THE BONES [FART I. tvvecn which the Membranes of the Wings are extend- ed, ace much elongated, especially the last, which have no Nails 5 but the Thumb is short, and furnished with a Claw, in form of a hook, by which the Animal can suspend itself when in a state of rest. The Glires have the Thumb short, but otherwise perfect. In the Ftra, the Toe, resembling the Human Thumb, is on the same plane with the other Toes ; of course they have not the power of grasping any thing. In some, as the Bear, Badger, &c. it is almost equal in length. In the Dog, Cat, &c. it is shorter. Each of the Bones of the last Phalanx in the Lion, Tiger, Cat, &c. is remarkable in having the fore part in form of a hook, which receives the Claw as in a sheath. The back part forms two Processes, to which the Muscles are attached, that can at once extend the Claw and bend the Phalanx. In Ruminants, the single Metacarpal Bone supports tiie two Toes which form the part termed Cloven Foot. Several species have besides two little Bones, frequently covered with Nails, which represent two other Toes ; but these are so short as not to touch the ground. There is here also a small Bone, which forms a Rudi- ment of the Thumb. In Solipeds, the only vestige of the lateral Toes are the two sharp-pointed Styloid Bones on each side of the Canon Bone. The three Bones of the single Toe are termed Pastern, Coronet, arid Coffin Bone ; the last of which is received into the Hoof. At the back part of the Pastern are also two Sesatnoid Bones. The Cof- fin PART I.] OF MAMMALIA. 21 fin Bone has a piece connected to it, under the name of Shuttle Bone. The Elephant has five perfect Toes, but they are al- most entirely concealed by the Skin of the Foot, In the web-footed Quadrupeds, as the Otter and Seal, and in the Pectoral Fins of the Cetacea^ the Bones analogous to those of the Hand are in a flattened form, and, in the latter kind of Animals, are often in a state of Cartilage. The Anterior Extremities of the Seal, &c. form a sort of medium between those of other Mammalia and the Cetacea, being more confined than the former, but less so than the latter. POSTERIOR EXTREMITIES. Os Femoris* In every class of Animals, the Os Fe~ moris, like the Os Humeri, is single. It varies in length according to that of the Metatarsus. In most Quadrupeds it is so short, that it scarcely projects be- yond the Abdomen, in consequence of which the Leg, properly so called, is commonly termed the Thigh. The Cervix of the Thigh-bone here is remarkably short, but the Great Trochanter rises considerably a- bove the head of the Bone. In some Animals, as the Horse, there is an Unciform Process. This, in the Rhinoceros, forms, with the Trochanter Major, a Fo- ramen between them and the body of the Bone. The Leg Bones are nearly as in Man, but the Tibia in general is considerably longer than the Os Femoris. In the Ape tribe, they are more nearly equal* In some B3 of 22 OF THE BONES [PART I. of this family, the Bones of the Leg and Thigh are much shorter than those of the Fore-arm and Hu- merus. In the Rat and Mole, the Tibia and Fibula form one continued Bone for a considerable part of their length. In the Rodentia, the Fibula is placed entirely behind the Tibia; also in the Dog, where the two Bones are attached through their whole length. . In the Horse y the Fibula is only a Rndimcnt anchy- losed by age to the upper part of the Tibia. In Ru- minants, it is wanting. In the Pig and Elephant > the Fibula is anchylosed through its whole length to the Tibia. Tarsus. In Quadrupeds with Toes, the Tarsal Bones have a near resemblance to those in Man ; they differ only in a few particular circumstances. In Mon~ keys, strictly so called, the Os Calcis generally wants the Tuberosity of the Heel at its Posterior Extremity ; and the Tarsus is articulated with the Leg Bones in such an oblique manner, that the Foot rests more on its outer edge than on the Sole. In some of the Lemurs, the Os Calcis and Os Scaphoides are so long, as to give the Foot the appearance of a Hand. In Carnivora, the Ginglymus at the lower end of the Tibia is more complete than in Man. The Heel is longer, and quite straight, in those that walk only on the Toes. In the Mole, the Tibia alone is articulated with the Tarsus. Rodentia have the Os Calcis much elongated. In some Animals, as the Opossum and ]3eaver, the Tarsus lias a supernumerary Bone on its inner side. Solipcds PART I.] OF MAMMALIA. 23 Solipeds have only two Cuneiform Bones in the Tar- sus. In Ruminants, the Scaphoid and Cuboid Bones are united together, except in the Ca?nel > which has them distinct. The Tarsus of die three-toed Sloth has only four Bones, viz. the Os Calcis, the Astragalus, and two Cu- neiform Bones. The Astragalus is articulated wit! the Fibula, with the Os Calcis, and the Great Cunei rm Bone, in such a manner, that the Foot possesses only lateral motion, but which is perfectly adapted to the re- quisite purposes of embracing and climbing the Trunks and Branches of Trees. Metatarsus. The structure of the Metatarsus is in ge- neral the same with that of the Metacarpus. The Ape tribe have the Metatarsal Bone of the Great Toe only about half the length of the others, but it can be readi- ]y separated to some distance from them. Solipeds and Ruminants have a single Metatarsal or Canon Bone of the Kind Leg, which, in the former Genus, and some- times in the latter, has a small Styloid Bone on each side. Toes. In Apes, the smaller Toes are longer than in Man. The Phalanges are much of the same nature with the corresponding parts of the Anterior Extre- mities. The Great Toe is shorter than the rest, but the Me- tatarsal Bone can move like the Thumb, in opposing the other Toes when the Animal is climbing trees, &c. The same thing takes place in the Genus Opossum) but this structure is only in the Posterior Extremity. In Carnivora in general, the Great Toe is united with, B 4 and 24 OF THE BONES [PART I, and parallel to the rest. The Bear, Badger, and Mole, have it nearly equal to the length of the other Toes, In the Dog, Cat, and Hare, it is almost obliterated. The Elephant has five perfect Toes, the Pig four. Solipeds have one perfect Toe, and two imperfect, articulated with a single Metatarsal Bone. Ruminants have two perfect Toes, and two small ones, attached to the under part of a Metatarsal Bone. Cdacea have no Bones in the Tail Fins, which correspond to tine Poste- rior Extremities of Quadrupeds. In clawed Animals, the Phalanges of the Toes of the four Extremities are the parts on which the Animal is supported. In hooved Animals, no part touches the ground but the last Phalanx. In the Bear, Pledge- hog, &c. a larger portion of the Foot touches the ground than in any other Quadruped. The Os Calcis comes near it ; but in none of the Mammalia except Man does the Foot rest completely on the ground. OF FART I.] OF MAMMALIA, 25 OF THE MUSCLES. JHE Muscles must vary in the different orders of Mammalia according to the nature of the Skeleton. The degree of resemblance between the Muscles of the Animals of this class, and those of Man, may be known in a general way, by comparing the Skeleton of any particular Animal with that of the Human Body. The Muscles in the Ape tribe bear the greatest re- semblance to those in Man ; but a striking difference appears in the former, on account of the smallness of the Fleshy part of their Hips, and in the diminutive appearance in the Calfs of their Legs. Muscles of the Integuments. Iir Mammiferous Ani- mals, with the exception of a few, as the Hog tribe, there is a thin Fleshy Expansion, termed Panniculus Carnosus, lying directly under the Skin. It covers the greater part of the Trunk of the Body, and also a por- tion of the Neck, Head, and upper part of the Thighs* Its Fibre? unite below the Axilla, where they are in- serted by one or two Tendons, along with the Tendon, of the Great Pectoral Muscle, under the Head of the Huineru?. It acts partly upon the Anterior Extremity, bufe 26 OF THE MUSCLES [FART I, but serves chiefly for the motions of the Skin. By it also, the Animal can make the Hair stand on end, par- ticularly in the Neck. The Skin of the Pledge-hog possesses a curious com- plex Muscle. It is of an oval form, and is placed along the Back, adhering closely to the Skin, and even to the roots of the Prickles or Spines. It sends slips to the Face, to the under parts of the Throat, Thorax, and Abdo- men, and to the lateral parts of the Tail. By the con- traction of these slips, assisted by the Flexor Muscles of the Head and Trunk of the Body, the Animal,, when in danger, can coil itself up as in a Sac. It re- turns to its ordinary posture, by acting with the middle part of the Cutaneous Muscle, the other parts becom- ing relaxed, so as to leave the lower parts of the Body, the. Hands, and the Feet free. In the Armadillo, the Cutaneous Muscle, though less strong and complex, is also of such a nature as to allow the Body to be coiled up. The Panniculus Carnosus exists also in the Dolphin* Muscles of the Eye and Ear. They will be noticed afterwards in the description of these Organs. Muscles of the Nose and Mouth. In slpcs, the Nose is affected by a continuation of the Panniculus Carno- sus. In Carnivora, as the Dog> the Nose is moved by the Levator Labij Superioris Alaeque Nasi, that covers the Cheek, and the Depressor Alas Nasi, which is small. In Animals with projecting moveable Snouts, as the J3ear and the Mole, the Cartilaginous Tube of the "Nose is moveable in every direction on the end of the Osseous PART I.} OF MAMMALIA. 27 Osseous Snout, by several Muscles. In the Mole and the Hog, they extend from the side of the Head and Bones of the Upper Jaw, and terminate by Tendons which are placed round the Nasal Tube. They serve for raising or depressing the Snout ; or, by the action of the Muscles of the same side, it is turned laterally. The Snout in both of these Animals is surrounded by Annular Fibres, which are a continuation of the Orbi- cular Muscle of the Lips. In Solipeds, besides Muscles analogous to the Levator Labii Superioris Alaeque Nasi in Man, there are others arising from the Bones in the neighbourhood, and fixed to the Nostrils, of which four are described by Authors, viz. the Pyramidalis, belonging also to the Mouth ; the Transversalis, which runs parallel to the Orbicularii Oris ; the Miisculus Brevis, which goes from the Nasal Bone to the False Naris ; and the Musculus Maxillaris, serving for the dilatation and contraction of the Naris. Ruminants have the Muscles of the Nose less compli- cated : two arise from the Os Maxillare, and go to the upper, outer, and tinder edges of the Nostril. The Proboscis of the Elephant has, between the Ex- ternal Integuments and the two Tubes which it con- tains, a thick Fleshy Layer, composed of two sets of small Muscles, or fasciculated Fibres ; an inner one, running in a transverse, and an outer one, in a longi- tudinal direction. Of the Transverse Fasciculi, some run across the Proboscis, others in a radiated, and some in an oblique direction, between the surface of the Tubes and the inner part of the longitudinal Fibres. These form the inner part or body of the Organ, The radiated 23 OF THE MUSCLES [PART L radiated and oblique Fibres approximate the Skin and the Tubes without contracting the cavity of the latter. The others, which go across the Proboscis, contract both the surface of the Organ and the Canals it contains* They can at the same time elongate the whole of the Organ, or a particular part only. The longitudinal Fasciculi form four large Muscles, which occupy all the outer part of the Organ. They are divided by Tendi- nous Intersections, and take their origin behind from the Bones of the Face. They serve to shorten the whole or a part, and give that extraordinary power which the Animal possesses of moving the Snout in every direction. The Muscles of the Mouth of Quadrupeds must vary according to the shape of the Lips. In the Dog, the Mouth is moved by six pairs of Muscles and a Sphinc- ter, viz. the Levator and Depressor Labii Superioris Alaeque Nasi, the former of which is principally used in snarling ; the Levator and Depressor Labii Inferio- ris, the Buccinator, and Masseter. The five first are nearly as in Man ; the last has many of its Fibres spread out upon the Buccinator, in consequence of which they can forcibly raise the corners of the Mouth. The Mouth of the Horse is moved by the following Muscles, viz. the Levator Labii Superioris, which in this Animal is used > in neighing, and in the Ass for braying ; a Muscle termed Pyramidalis, analogous to the Levator Labii Superioris and Levator Anguli Oris, arising from the fore part of the Superior Maxillary Bone at the Zygoma, and fixed to the Ala Nasi and Corner of the Mouth 5 another Levator, termed Max- FART L] OF MAMMALIA. illaris, coming from the Forehead, and going o outwards by two slips to the wing of the Nose and angle of the Mouth ; the large Zygomatic Muscle ; the Buccinator ; the Levator Anguli Oris, termed Molaris, spread out upon the Buccinator ; the Depressor Labii Inferioris ; two small Muscles, termed Middle Superior and Middle Inferior of the Lips ; and the Orbicularis. Muscles of the Lower Jaw. The Temporal Muscle in the Ape kind differs but little from that in the Human Body. In the Fer the Muscle is less extensive than in the former \ but in some of the Rat kind, the Muscle is so extensive, as almost to meet its fellow on the op- posite side of the Head. The Masseter agrees with the Temporal Muscle in being thick and strong, corresponding with the force required in bringing the Jaws together. Besides the Muscles mentioned above, and which are common to Quadrupeds in general, many of the Glires, as the Squirrel, Rat, &c. have a fifth pair, for assisting in the elevation of the Under Jaw. Each takes its origin from the Upper Jaw, near the Infra-Orbitar Foramen, and is fixed to the Lower Jaw near the Pterygoideus Externus. The Pterygoid Muscles only vary in size and length, and in the obliquity of their Fibres, corresponding with the size and form of the Jaw. The Digastric, in the Ape tribe, only possesses two distinct Fleshy Bellies, and a middle Tendon, per- fora ting SO OF THE MUSCLES [PART t forating the Stylo-hyoid Muscle. Among the there is only one Belly, and it runs forward to be fixed to the Base of the Lower Jaw, most frequently a little beyond the Masseter. Among the llodenlia, it is continued to the Chin, to which it is fixed. In other Mammalia, it vanes a little in its general appearance and attachment, according to the nature of the Jaw, and of the motions it has to perform. Muscles about the Neck and Throat. The place of the Platysma Myoides is supplied by the Panniculus Carnosus. The Sterno-mastoideus is nearly as in Man, but is blended in various ways with the Trapezius and Del- toides. / The Sterno-hyoid and Sterno-thyroid Muscles arise in common from the Cartilaginous Extremity of the first Rib ; but in the Lion, the origin of the former extends in the Thorax along the three anterior Bones of the Sternum. In the Seal, where the Anterior Extremity of the Sternum is slender, the Sterno-hyoideus arises from the first Rib. The Stylo-hyoideus is perforated by the Digastricus in the Ape, but not in other Quadrupeds. In Quadrupeds possessing a Styloid Process, there is- a Muscle peculiar to them, termed Stylo-mastoid&us, which arises from the outer surface of the Mastoid Pro- cess, and is fixed to the Styloid, which it raises out- wards. Some Carnivora have also a small Muscle fill- ing the space between the Cornua of the Os Hyoides. The PART L] OF MAMMALIA. 31 The other Muscles connected with the Os Hyoides vary in different Animals, according to the shape of the Bone. Muscles situated on the Inferior and Lateral Parts of the Abdomen. The Abdominal Muscles differ from those in Man chiefly in regard to their proportional length. This difference is most remarkable in the Recti of Carnivora, which often extend as far as the Anterior Extremity of the Sternum. In such cases the Pyra- midales are frequently wanting. Muscles of the Parts of Generation^ see Articles Parts of Generation. Muscles situated within the Cavity of the Abdomen. The Fleshy part of the Diaphragm is generally broad- er in proportion, and it has more extensive motion than In Man, not being so firmly united to the Pericardium. The Quadratus Lumborum, Psoas Parvus, Psoas Mag- nus, and Iliacus Internus, are present in most Quadru- peds. They differ only in proportion, which depends upon the number of the Vertebrae of the Loins, and the length of the Os Ilium. Muscles situated upon the Inferior and Lateral Parts of the Thorax. The Pectoralis Major is for the most part proportionally larger than in Man, and is divided into se- t'eral portions, giving, in some measure, the appearance of as many distinct Muscles. In Carnivora, the insertion of the Muscles extends as far as the under part of the Hu- inerus. The Pectoralis Minor in Carnivorous Animals and Ruminants, is wanting; ^but in the Horse, its place ^s supplied by another Muscle, though this is so con- nected 32 OF THE MUSCLES [PART L- nected with the Pectoralis Major, as to go partly to the Humerus. The Subclavius, in the Ape tribe, is as in Man ; in Mammalia without Clavicles, it is wanting. The Serratus Magnus is more extensive in the Infe- rior Mammalia than in Man, being attached not only to the Ribs, but to the Transverse Processes of the/ Cervical Vertebrae. Muscles situated between tJie Hibs, and within the Tho- rax. The Intercostal and Sterno- costal Muscles are nearly as in Man, only the latter Muscle is generally larger, and may therefore act more powerfully upon the Ribs. Muscles situated on the Inferior part of the Vertebrae of the Neck. The Muscles on the inferior part of the Vertebrae of the Neck are not materially different from the corresponding Muscles of the Human Body, but generally have their Fleshy Bellies proportionally larger and more distinct. Muscles of the Spine and Superior Parts of the Trunk in general. In Apes, the Muscles of the Spine differ only in the strength of their Tendons. In the other Mammalia, they differ in the number of their attach- ments, which depends upon that of the Vertebrae. The motions of the Os Coccygis are much more visible in the rest of Mammalia than in Man. The Tail, which is merely an elongation of it, can in general move readily in every direction ; may even be turned upon its own axis, or rolled spirally. The Muscles of the Os Coccygis in Animals with prehensile Tails are remarkably nonierous, to assist them FART I.] OF MAMMALIA. 3 them in climbing, as in the Monkeys and Opossums, or in springing, as in the Kangaroo. The Spine of the Horse is remarkable on account of the great breadth of the Ligamentum Nuchae, which assists in supporting the Head. There is likewise a peculiarity of this substance in the Mole, where a large portion of it is ossified, being employed in throwing up the earth. , The small Muscles of the Head exist in Quadrupeds as well as in Man. In general, the Complexus has one continued Fleshy Belly, though, in the Ferae, there are Tendinous Intersections through its whole length. The Splenius is inserted into the Ligamentum Nuchae in such Animals as have this Ligament considerably raised nbove the Vertebrae. MUSCLES OF THE ANTERIOR EXTREMITIES. Muscles of the Shoulder. The Serratus>Magnus, Pec- toralis Minor, and Subclavius, have been already taken notice of. In the Ape, the Trapezius resembles that in Man 5 but in other Quadrupeds, it is complicated with the Sterno-mastoid and Deltoid Muscles, and in some with the Levator Scapulae, which has great variety in the number and insertions of its Tendon in different Qua- drupeds. In the Rabbit, a peculiar Muscle arises from the fore part of the Spine of the Scapula, and is inserted into the Clavicle. The Rhomboid in Apes is extended as VOL. IV. C % 34 OF THE MUSCLES far as the Occiput. The Occipital portion of it, in Carnivora, forms a Muscle termed Levator Scapula; Magnus. The Omo-hyoideus is wanting in Animals which have no Clavicle nor Coracoid Process, as in Dogs. The Subclavius is present in Animals with, but absent in those without Clavicles. Muscles of the Arm. All the Muscles of the Hume- rus exist here, but with some variety. The Pectoralis Major, as already mentioned, is generally more Fleshy, and divided into different portions. The Latissimus Dorsi differs little. The Supra-spinatus, Infra-spina- tus, Subscapularis, Teres Major, and Teres Minor, differ chiefly in their proportions, corresponding with the form of the Scapula. The Coraco-brachialis exists in Quadrupeds in general ; but in those wanting the Coracoid Process, it arises from the upper edge of the Scapula. Monkeys have the Coraco-brachialis divided into two portions, one of which extends along the whole length of the Humerus. ? Muscles of the Fore-arm. The Biceps and Brachialis Internus are similar in Monkeys to those in Man, except that the Brachialis arises almost as high as the Neck of the Humerus. In many Quadrupeds, as the Dog, Cat, Horse, &c. "A 1 t- the Muscle corresponding to the Biceps has only one Head, which has no connection with the Coraco-bra- chialis. In Monkeys, the Triceps has an additional portion, which arises from the Tendons of the Latissimus Dorsi t and Teres Major. In many other Animals, this fourth portion is found. In Quadttipeds in general, the Ex- ten s.or FART I.] OF MAMMALIA. SS tensors are complicated, and of great strength, corre- sponding with the purposes required in their progres- ive motion. In the Cetacea, where the two Bones of the Fore-arm are not moveable upon the Humerus, the Triceps is wanting. But the Anconeus is present in all the Animals mentioned above. Muscles of the Hand. Apes "have Supinators similar to those in Man. The Dog and Cat have the Supina- tor Brevis, but the Longus is wanting. They are both wanting in Solipeds, Ruminants, and Bellu&. The Pronators are the same in Apes and Carnivora as in Man. Solipeds and Ruminants have no Pronators. The number of Flexors and Extensors of the Hand is nearly the same in Monkeys, and other clawed Quadru- peds, as in Man. In Quadrupeds with a Canon Bone, the Extensor Carpi Radial is is inserted into the fore part of the Base of that Bone, which it extencts ; and the Flexor Carpi Radialis is inserted into the back part of the Base. The Flexor Ulnaris and Extensor Ulna- ris are fixed to the Bone that corresponds to the Us Pi- fiiforme. The three last Muscles are Flexors in these Animals. Muscles of the Fingers. The Extensor Digitorum Communis, in Quadrupeds with four Fingers or Toes independent of the Thumb, has four Tendons, in Ru- minants two, in Solipeds only one. The Extensor Pro- prius Digiti Minimi, in Monkeys, sends Tendons to the fifth and fourth Fingers; in l>ogs and Bears, to the fifth, fourth, and middle Fingers. In Solipeds, there 4a*e two Extensors fixed to the first Phalanx^ of the Toe, C 2 In 30 OF THE MUSCLES [PART I. In Ruminants, this Muscle extends the Outer Toe, and the Extensor Indicis the Inner Toe. The Extensor Indicis Proprius, or Indicator, in . Monkeys, sends a Tendon to the fore, and another to the middle Finger. In Dogs and Cats, it is situated as in Man. In Solipeds and Ruminants, it is wanting. The Extensor Ossis Metacarpi Pollicis is similar, in Apes and many other clawed Animals, to that in Man. In Solipeds and Ruminants, it is fixed to the Base of the Metacarpal Bone, and forms the Oblique Extensor of the Canon Bone. The Extensor Primi Internodii is present in Apes^ Dogs, Cats, &c. The Extensor Secundi Internodii Pollicis is indistinct in Apes, and wanting in the Dog, Cat, &c. In Solipeds and Ruminants, the two last- named Muscles are wanting. The Flexors of the Thumb, in clawed Quadrupeds, are somewhat similar to those in Man. In Ruminants, the Flexor Sublimis and Flexor Profundus of the Fin- gers send each two Tendons to the Toes. In Solipeds, there are two similar Muscles, but only a single .Tendon,, to each, the one also perforating the other. MUSCLES OF THE POSTERIOR EXTREMITIES. Muscles of the Thigh. In the generality of Quadru- peds, the Gluteus Medius and Minimus are large. In the Horse, the Muscle corresponding to the Maxi* jnus in Man is the smallest of the three, and is almost Aponeurpti?, FART L] OF MAMMALIA. S? Aponeurotic. The Medius in that Animal is the Mus- cle principally used in kicking. In the Bear, however, the Glutens Maximus is so Large, compared with the other Muscles, as to enable the Animal frequently to put itself into the upright posture. The Iliacus Interims and Psoas Magnus are general- ly in proportion much longer than in Man, correspond- ing with the greater length of the Pelvis. The Pecti- neus, in the Dog, is peculiar for extending to the bot- tom of the Os Femoris. In the Cctacea, the Muscles of the Thigh are entire- ly wanting. Muscles of the Leg. In Apes, the Muscles here are similar to those in Man, except that corresponding to the Biceps, which has only a single Head. In the Ro- dentia and Carnivora, the Extensors of the Knee at the Posterior Extremity, are smaller than in Man, while the Flexors are stronger, corresponding with their pur- poses of walking. The Sartorius and Gracilis form the anterior edge of the Thigh. In all Quadrupeds, the short head of the Muscle analogous to the Biceps is wanting ; but the single head not only covers a great part of the outer side of the Thigh, and is inserted into the Fibula, but gives Fibres to the whole length of the Fascia Lata, and performs die office of an Exten- sor of the Thigh. In all Quadrupeds, the Gracilis is large j the Semimembranosus and Semitendinosus, which are never wanting, are inserted so much farther down the Tibia than in Man, as to keep the Limb in a state of semiflexion. This is found to be a principal cause in preventing Quadrupeds from walking in an C 3 erect 3S OF THE MUSCLES [PAF/T I. erect aUitude. The other Muscles are nearly as- in Man. Muscles of the Foot. The Gastrocnemius is always present, but the Soleus is smaller than in Man, and is remarkably slender in Solipeds and Ruminants. In Monkeys, the Plantaris is continued over the Os Calcis, to the Aponeurosis Plantaris. The Tibialis Anticus, in Animals* which have no Great Toe, as the Dog and Rabbit, is inserted into the first of their Toes. In So- lipeds and Ruminants, it is inserted into the Base of the Canon Bone. The Tibialis Posticus, in Animals desti- tute of a Great Toe, is inserted into the first Toe. It is wanting in Quadrupeds with Canon Bones. The Peroneus Longus, in the Ape kind, is peculiar for drawing the Great Toe towards the other Toes. In Animals without a Great Toe, it is inserted into die Metatarsal Bone of the first Toe. In Ruminants, it crosses over the Joint of the Canon Bone, to be insert- ed into the first Os Cuneiforme. The Peroneus Brevis and Tertius, in clawed Animals, are as in Man. The Horse has but one Peroneus. In Ruminants, the Pe- roneus Brevis is wanting. Muscles of the Toes. Monkeys have two Extensors of the small Toes ; but, besides an Extensor Pollicis, there is an Abductor Longus Pollicis, which is peculiar to this tribe of Animals. Other digitated Animals have the same number as in the. Human Body. The Extensor Pollicis is wanting in Animals destitute of a Great Toe, as the Dog and Rabbit': In Solipeds arid Ruminants, the Fleshy Fibres arise from the Canon Bone, and are inserted into the Tendon of the Exten- 01 ART I.] OF MAMMALIA. 59 sor Longus, of course supplying the place of the Ex- tensor Digitorum Brevis. In Ruminants, there is an Extensor Proprius analo- gous to the Extensor Pollicis ; but in Solipeds, it is wanting. In Monlceys, the Aponeurosis of the Sole, continued from the Plantaris, must affect the Metatarsal 'Bones, into which it is inserted. The long and short Flexors of the Toes are confusedly connected to each other, and to the Bones of the Foot and Toes. The Massa Carnea is attached not only to the Flexor Longus Digitorum, but to the Flexor Longus Pollicis. In other Quadrupeds, the Flexor Brevis Digitorum is wanting, but its place is supplied by the Plantaris, which is proportionally strong, and has its Tendons perforated by those of the Flexor Longus, the number of which is equal to the number of the Toes. Though the Great Toe is wanting in these Animals, they have a Flexor Longus Pollicis, the Tendon of which is united to that of the Flexor Profundus. 04. Of OF THE INTEGUMENTS OF THE COMMON INTEGUMENTS JL HE Integuments in Mammalia consist of the same number of Layers as in Man ; but these vary not only in different Species, but in different parts of the same individual. The Cuticle is more or less dry, according to the ele- ment in which the Animal lives, being like horn in those that live in the Air, and more of a Mucilaginous nature in such as inhabit the Water. In general it is uniform in its texture, but is often marked with lines corresponding with inequalities of the Cutis Vera. In particular parts of some Animals, as in Apes and Ba- boons, in the parts on which they sit, it is remarkably thick, while in the points of their Fingers it is thin and delicate. In some, as the Elephant, it forms a horny covering. In some, it is detached from the Skin in the form of scales ; in others, it comes off at the same sea- son with the Hairs. In the Cetacea, it is remarkably smooth, being always covered with an oily matter, which defends it from the water in which it is constant- ly immersed. The Corpus Mucosum varies in thickness in different Animals* PART I.] OF MAMMALIA. 41 Animals, and sometimes in different parts of the same individual. In the Cctacea, it is thicker than in any other Animal. The colour of this substance is also very variable. In some Apes, it is white bu the Cheeks ; in others, it is of a violet or carmine colour on the Nose and Buttocks. On the Belly of the Whalc y it is of a silver white. A connection also is observed to subsist between the colour of this substance and that of the Palate and Iris. The Cutis is more variable in its thickness than the Cuticle. In the Wing of the Bat, it. is remarkably thin. In most of the Belltuz, again, as the Elejthaitf and Rhinoceros) it 'is of great thickness, but much more so on the Back than the Belly. In these Animals, it ia deeply fissured. The Cuticle, here ako very thick, fol- lows the fissures to their bottom. The Nervous Papilla of ihe Skin are nearly of a si- milar nature in all the Mammalia as in Man, but are most distinct in parts most susceptible of touch. Their gures vary considerably, but their structure is nearly the same, as may be seen by macerating them for some time in wai;er. They are rery apparent in the Snout of the Mole, Uog, Elephcnt, Sec. and on the Fingers of the Monkey tribe. T.iey have a thread-like form on the Paws of the Bear, and some of the other digitated Animals. They have an elegant appearance at the Teats of the Balena, or true Whale -, and are very dis- tinct on the Tongue of the Solipeds and Ruminants 9 and in the Wings of the Bat, A sixth sense has o* late been ascribed to the Nervous Papilke in th^ Skin, of jhe Bat, which is found to pre- ' vent 42 OF THE INTEGUMENTS [PART!. vent the Animal from coming against external objects, even when the Eyes, Ears, and Nose are shut. This is considered to be partly owing to the Nerves which are so plentifully dispersed between the Integuments of the Wings, and is imagined to be something similar to that Sensation by which a blind person discerns, by the Hands and Face, his approach to a wall, or to the door of a house, &c. before he touches them, and mere- ly by the shock given to the air. The Cellular Substance in Mammalia is, as in Man, commonly filled with Fat, the consistence of which va- ries according to the Species, and the state of the Body. In Ruminants, it is of a firm consistence, and forms the Tallow. In the Pig, it is thicker and more uni- form, and has the name of Lard. In the Cetacea, where it forms the Blubber, it is still thicker than in the Hog, but is so fluid, that on a cut being made into the Skin, and without any pressure being applied, it runs in the form of Oil. In this last tribe of Animals, it renders the Body specifically lighter, while, at the same time, it prevents the coldness of the water from affecting the Blood, which is found to be about the heat of the rest of the Animals of this class. The surface of the Skin of Quadrupeds is lubricated, like that of the Human Body, by an unctuous matter, which defends it from the action of the surrounding- clement, and which, in the Dog kind, must supply the want of sweat, that excretion, in these Animals, in some measure passing off, or at least its want being supplied, by a free discharge from the Salivary Glands. In many, as the Horse > a lubricating liquor is pro- duced, FART I.] OF MAMMALIA, 43 duced, which covers the Skin, and extends along the Hairs; or a greasy matter is discharged from visible Follicles on certain parts, as in the Axillae and Knees of the Animal just mentioned. Glandular Follicles are in some collected into masses, and appear in certain parts of the Body, as in the Groins, The secretions from the Skin, in some of the Mam- malia, have peculiar smells, by which ojie Animal can follow the track of another, or the Dog even, trace the footsteps of his master. Under the Common Integuments is the Panniciilm Carnosus, which has already been taken notice of in the description of the Muscles. All Quadrupeds have Hairs more or less numerous,, or something of a similar nature, to protect them from the effects of the weather, or from external injury, or to serve as ornament. They are commonly in greater abundance on the upper, than the under parts of the Body, and, as in Man, they are implanted in the true Skin, and sometimes go as deep as the Panniculus Car- nosus. The form of the Hair is commonly cylindrical, as in the Horse, but sometimes is flat, as in the Toes, of the Oriiilhorrynchus and common Porcupine, Whiskers of the Seal, and Tail of the Hippopotamus ; or they are curled and waving, as in many Ruminants. The texture is affected by climate and manner of life. They are long and stiff in northern regions, as in the Hog of Siberia, and Sheep of Iceland ; fine and silky in southern parts, as in the Dog of Malta, Cat, Rabbit> 44 OF THE INTEGUMENTS [PAIMP L Mild Goat of Angola ; thin, or almost wanting, as in the Dog of Guinea, and Sheep of Africa. The colour of the Hair is for the most part nearly the same with that of the Corpus Mucosum ; but the colour is observed to reside under the Cuticular Cover- ing, and not in the Pith or Medulla. Some of the larger Bristles, as the Whiskers of the Cat, have a small Canal internally, while the Prickles of the Hedge- hog, and Quills of the Porcupine, are furrowed on the surface, and arc filled with a white substance inter- nally. In some Animals, as the Sheep, the Skin is covered with Wool in place of Hairs ; in the Martin, tier- mine, &c. with a silky stuff, which forms the Furs ; or in the Pig, with Bristles ; or in the Pledge-hog, with Spines or Quills ; or in the Armadillo, with hard Plates laid like tiles on a roof, &c. Animals are commonly born with Hairs upon them, though in some they are not observed till a certain period of life, and then only on certain parts of the Body. The Hairs in Mammalia have nearly the same component parts, and grow in the same manner, as in Man. The Horns are found chiefly on the Heads of Rumi- nants, though, on particular parts of the Body, in many other Animals. They are commonly formed on Processes of the Frontal Bone, and grow from the base at an early period of life. The Skin of the part which, by its protrusion, is afterwards to form the Horn, becomes callous, then gradually changes into Horn. In some, as the Ox, the Horns aye round ; in others, 4* PART I.] OF MAMMALIA. 45 as the Sheep i they are flat, and they form different cur- vatures according to the kind. Between the Process of Bone and the Horn covering it, a soft Vascular Sub- stance is interposed, which, while it nourishes the out- side of the Bone, produces the Horn in successive Layers, sent off upon the internal surface. As the Ani- mal advances in life, Furrows extend across the root of the Horn, from which, by experience, the age of the Animal can nearly be known. The Horn of the R}u>~ noceros only differs from that of Ruminants, in being situated over the Bones of the Nose, in appearing to take its origin from the Skin, and in having no Osseous matter within. The colour of the Horns, as of the Hair, depends upon that of the Corpus Mucosum. In their consist- ence they are solid, insensible, and of a Fibrous tex- ture ; the Fibres bearing a considerable analogy to the Hairs, as may be more distinctly seen jn the Horn of the Rhinoceros. They are more or less transparent ac- cording to their thinness. When artificially softened by hot water, &c. they may be bent in any direction, ajid moulded into any form. The Antler of the Stag differs from Horn, in grow- ing from its extremity, and not from its base ; in being covered, at a certain period, with Hairs ; and in being deciduous. It is a real Process of Bone, appearing, when fully grown, a continuation of the Os Frontis, and is covered, during the time of its growth, with a Periosteum and a hairy Skin, which is very Vascular; the Vessels passing through an Osseous circle at the root 46* OF THE INTEGUMENTS [PART L root of the Antler. The growth is commonly finished before the end of the third month. When it is completely formed, it loses its covering of Skin and Periosteum, in consequence of the Vessels at its root being obstructed, and remains afterwards quite bare; no distinction being now to be observed, but an irregular projection of a circular form at its base. When it drops from the Head, the Integuments close over the Bone with which it was connected, till the period of its renewal returns, when a Process pro- jects, and forms the succeeding Antler, which is always found to be longer than the preceding one. It is also observed, that the Branches of the Carotid Artery, which supply this substance, are dilated during its growth, but return to their former dimensions when it has acquired its full size. The Nails and Claivs cover the last Phalanx of the Toes of Quadrupeds, and are. of the same nature, and formed after the same manner, as Horns. They grow from the base to which the Integuments are fixed, and commonly cover the upper part of the Toes ; but in some, as the Squirrel, Rat, &c. they entirely surround them. They belong to Quadrupeds in general, and are originally formed before the birth of the Animal. Their colour, as in the Horns, depends upon that of the Corpus Mucosum. They serve for rubbing, scraping, and for catching tlie prey, and, in general, to protect the extremities of the Toes. They have no sensibility but at their roots. They are wanting in those Animals which do not use the Toes for walking, or for laying hold of the food, Jn PART L] OF MAMMALIA. 47 In such Animals as frequently dive or swim, the Toes are inclosed in Membranes. In the Cetacea, they are concealed under the Skin, and form the Fins. All Ruminants, and many of the Bellua, have two Toes inclosed in triangular Hooves, which form a mould on which they walk. Solipcds have but one Toe, the last Bone of which is inclosed in a semicircular Hoof, which supports them in walking. Tin's is com- posed of a horny covering, similar in its structure and formation to the Hooves of Ruminants; but it incloses the whole Bone. The internal surface is formed into numerous Laminae, which have intermediate Layers of Vascular matter for their nourishment. In the inferior part of the Hoof, there is a soft matter full of Nerves, and very sensible when punctured. Besides the parts mentioned above, there are others connected with the Common Integuments, destined for {he secretions of peculiar fluids. These occur in cer- tain Genera and Species belonging to particular classes of Animals. In the Temple of the Elephant is a Gland, from which a Duct runs downwards and forwards, and ter- minates halfway between the Eye and the Ear ; through this, in both sexes, but more especially in the Male, a brownish liquor is discharged upon the Skin at rutting- time. In the Deer, Antelope, and Hare, are Membranous Sacs, with Follicles opening into them, placed in a Sub : orbitar Fossa of the superior Maxillary Bone. From these a Viscid, Adipose, dark Fluid is discharged by a clifc 43 OF THE INTEGUMENTS [PART I. elift in the Skin. This liquor was formerly supposed to have some relation to the Tears. In the substance of the Prepuce of the Glans of the Penis and Clitoris, in many of the Glires and Carnivo- ra, as the Rat, Lion, Civet, &c. are two sets of Glands, termed Preputial, one consisting of simple Follicles, the other of Conglomerate Glands. Each sends out a Duct, which discharges a Sebaceous matter, to defend the parts near them. In the Prepuce of the Beaver are similar Glands, which furnish the Castor. They form a mass, that has a bag near it which contains this substance, and opens at each side of the chink common to the Anus and Penis. In the male Musk Goat, {Moschus Moscifer), are parts similar, and similarly si- tuated, to those of the Castor. They are of an oval form, and are full of Follicles, which separate the Musk. IH the Hare, and the greater part of Ruminants, are Glands tinder the Skin of the Groin, and therefore termed Inguinal, which secrete a Sebaceous feetid sub- stance, and send it into Cavities, from which it is dis- charged by an orifice at each side of the Prepuce. In many of the Glires, but especially in Land and Amphibious Carnivora, as the Badger, Civet, Pole-cat^ Dog, Fox, Lion, &c. peculiar Glands and Bags are found near the outer end of the Rectum, and therefore called Anal. They are commonly of a spherical shape s and have a single orifice frequently ending at the side of the Anus. They secrete a matter of various colours, but commonly yellow or brown, of a strong disagree- able smell. In the Badger, Pole-cat, and Fox, the smell I.] OF MAMMALIA, 49 smell is remarkably strong ; and some of the Weasel tribe in America, as the Skunk and Squashy are ob- served, upon being pursued, to pour out the Contents of these Bags so profusely, that their followers cannot approach them. The matter secreted in these Bags may be excremen- titious in some Animals, but in others, it appears to lubricate the Skin, and defend it from being injured by the Foeces. The Badger, Opossum, and other Marsupial Animals, have Pouches on the Abdomen, lined with fine Hair, and discharging from their surface secretions of a Seba- ceous nature, which, when recent, smell disagreeably* but are found, after being dried, like the Scent Bags in many other Animals, to acquire an agreeable musky smell. Over the Sacrum of the Aper Moscifer, or Mexican Hog, there is a Gland termed Dorsal, some inches in length, and lobulated, from which a Duct opens on the Skin, and pours out a liquor of a musky smell. In the Feet of several Ruminants, especially in Sheep, are Glandular Cavities, lined with Hair, and sending out an Excretory Duct, which opens at the junction of the Hooves, VOL. IV. D OF 50 % OP, THE MAIN OF THE BRAIN. J HE Brain in Mammalia completely fills the Cranium j and has nearly the same parts as in the Human Bo^ cly ; but there are certain peculiarities which distin- guish the Brain of all other Animals from that of Man. These consist chiefly in its being much smaller in proportion to the Body, and also to the Cerebellum and Spinal Marrow^ but more particularly to the Nerves arising from it. To this last circumstance there are ho exceptions, though there are several to the * others. Some of the Ape. and Mouse kind equal Man in the proportion of the size of the Brain, and certain Birds surpass him ; but, according to SOEMMERRING and ELBE, the size of the Brain, to the Nerves arising from it, bears an exact ratio to the faculties of the Ani- mal's Mind ; and though^ in some small Animals, the Brain is proportionally larger to the size of the Body than in Man, yet all, even the Monkey tribe, are far inferior to him in respect to the proportion between the Brain and Nerves. The projk)rtion the Brain bears to the rest of the Body it is difficult to ascertain, oh account of the diffe- rent PART I.] OF MAMMALIA. 51 rent states of fatness and leanness of the Body ; but, taking things in a very general way, it is found that small Animals have the Brain largest in proportion. The largest Brain SOEMMERRING found in the Horse weighed 1 Ib. 4 oz. while the smallest in Man was 2 Ib. 5| oz. -, yet the Nerves in the former were ten times larger than those in the latter. Dr Monro found the Brain in the Ox only one-fourth the weight of that of the Human Brain, while the weight of the Body of the former was six times greater than that of the latter ; or, the Human Brain is twenty- four times greater in proportion to the weight of the Body, than that of the Ox. In Man> at different times of life, its weight varies from a 22d in a young person, to a 35th of the Body in a Subject'advanced in life. In the Ourang-outang, it is a 48th ; in other Apes, it varies from a 22d to 'up wards of a 100th ; in the Mouse* it is -a list; in the Rat, a 76th ; in the Hare, a 228th ; in the Mole, a 36th ; in the Dog, from a 47th to a 305th ; in the Cat, a 94th ; in the Bear, a 265th -, in the Horse, a 400th ; in the Ox, an 860th \ in the Hog* from a 412th to a 512th ; in the Dolphin, from a 25tlt to a 102d; in the Porpoise, a 9 1st.. The proportion the Cerebrum bears to 'that of the Cerebellum is as follows : In Man, as 6 to 1 ; in Apes, from as 6 to 1 to as 14 to 1 ; in the Mouse, as 2 to 1 5 in the Rat, as 3~th to 1 -, in the Hare, as to 1 ; in the Mole, as 4^ to 1 $ in the Dog, as 8 to 1 ; in .the Cat, as 6 to 1 ; in the Horse, as 7 to 1 ; in the Ox, as *)'to 1 ; in the Sheep, as 5 to' 1, D 2 The 52 OF THE BRAIN [PART I, The proportional breadth of the Brain to that of the Medulla Oblongata, is greater in Man than in other Mammalia, with few exceptions. In Man, it is as 7 to 1 ; in Apes, from as 4- to 1 to as 5 to 1 ; in the Dog, as 11 to 6 5 in the Cat, as 1 1 to 4 ; in the Horse, as 21 to 8 ^ in the Ox, as 13 to 5 5 in the Deer, as 5 to 2 ; in the Dolphin, as IS to 1. The Falx of the Dura Mater, in Mammalia, is smaller in proportion than in Man ; the Hemispheres being less in danger of injuring each other. It is of different breadths in different Animals. In some few individuals of the class, as the Ornithorrynchus and Porpoise, it is partly Osseous. The Tento- rium in Quadrupeds is proportionally broader than in Man ; and in many, particularly the Carnivora, it contains in its substance a plate of Bone. In the Cat and Bear kind, this plate is in one piece ; in the Horse, Dog, and Seal, in three. The Osseous Tento- rium is commonly considered as obviating the effects of concussion, though it is found in some Animals of slow, as well as in those of quick motion. The Falx Minor is wanting in Quadrupeds. The other two Membranes of the Brain are similar to those in the Human Spe- cies. The form of the Brain varies in different Animals. In the Ape tribe, it is oval, as in Man ; in Carnivora, and some others^ as the Hare and Rabbit, it is narrower anteriorly ; others have the Cerebrum almost round. In the Dolphin, it is remarkable, in being twice as broad from one side to the other, as from before back- wards. The PART I.] OF MAMMALIA. S3 The Lobes of the Brain, particularly the Lateral, are not so prominent in other Animals as in Man, though there is considerable variety here among diffe- rent individuals. In the Ape, there are Posterior Lobes, and these lie over the Cerebellum, as in the Hu- man Body 5 but in other true Quadrupeds, the Poste- rior Lobes, strictly so called, are wanting ; the Cere- bellum lying exposed behind the Cerebrum. If! the Dolphin, the Cerebellum is covered by the Cerebrum. The circumvolutions of the Brain are not so deep in other Mammalia as in Man, and they are generally less numerous. In the Ape, they are much fewer. In the Rodentia, as the Mouse, &c. there are, in general, no distinctly marked convolutions ; though they are nume- rous in Carnivora, Solipeds, and Ruminants. In all Mammalia, the Cerebellum is marked nearly as in Man, with Transverse Fissures, which, in Carni- vora, Solipeds, and Ruminants, divide it into Lobules, forming Convolutions somewhat as in the Cerebrum ; but these vary much in different Animals. The middle Lobes of it are proportionally larger than in the corre- sponding parts of the Human Body. The Cortical and Medullary parts of the Brain are similar to those in Man. The Corpus Callosum, Cor- pora Striata, and Fornix, vary only a little in their breadth, the last frequently covering a considerable por- tion of the Optic Thalami. The Lateral Ventricles have no Digital Cavities, in consequence of the absence of the Posterior Lobes. The Cornua Ammonis are, in general, larger in pro- portion, but they are not so prominent on the surface. D 3 , In 5* OF THE BRAIN [PART I. In the Horse, Ox, Sheep, &c. the third Ventricle forms a sort of circular passage, which surrounds the Commissura Mollis of the Optic Thalami. The fourth Ventricle has nothing remarkable about it ; the Arbor Vitae, in the substance of the Cerebellum, has a con- siderable resemblance to that in the Human Brain. The Tubercula Quadrigemina are larger, hence bettcf named Nates and Testes in the Quadruped, especially in Herbivora, than in Man, though they are more nearly of the same size in the Ape. The Nates are Cortical, and the Testes Medullary ex- ternally, as in Man. In Carnivorous Animals, the Testes are generally larger than the Nates. In the Dolphin, they are triple the size. In Jlerbivora, the Nates, on the contrary, are much larger than the Tes- tes, and are of a round form. The Pineal Gland, in Quadrupeds, is similar to that in Man, but is generally more conical and pointed. The Acervuius Cerebri, so frequently occurring in, or near, the Pineal Gland in the Human Brain, is seldom met with here. It has been seen in some of the Pecora, as the Fallow Deer ai,J Goat. The inequalities at the Base of the Brain are much less considerable than in Man. The Tuber Annulare is less prominent. In Carnivora, there are two Cor- pora Albicantia ; in Herbivora, there is only one. The Corpora Pyramidalia are considerably longer than in the Human Species. PART L] OF MAMMALIA, OF THE CEREBRAL NERVES. There is nothing very particular in the origins of the Cerebral Nerves, excepting the Olfactory. These Nerves, in the Ape tribe only, resemble those in Man. In other Quadrupeds, they form two large Eminences, termed Processus Mammillares, which are chiefly of a Cineritious nature, and fill the Fossa of the Ethmoid Bone. They are remarkable for their size in Herbivo- rous Animals. Each contains a Cavity, which commu- nicates with the anterior part of the Lateral Ventricle of that side by a small passage ; of course, there are six Ventricles in proper Quadrupeds. This circumstance gave rise to the ancient opinion, of the first pair of Nerves conducting the Pituita from the Brain to the Nose. The number of the Nerves from the Brain is the same as in Man. They vary chiefly -according to the form and extent of the parts .on which they are dis- persed. From the First Pair, numerous Fibrillae come off, to be distributed upon the different parts in the upper por- tion of the Nose. In the S/ieep, there is also a Branch, arising, within the Cranium, from the upper part of the Trunk of the Nerve. In the Dolphin and Porpoise, the Olfactory Nerve is entirely wanting. The Optic Nerves are conjoined as in Man, but they appear to be still more intimately incorporated. In large Animals, the, Fibrillae composing these Nerves are so separated from each other by the Pia Mater, that D 4 after SO OF THE BRAIN, Sec. [PART L after the Medullary Substance is dissolved by macera- tion, the remaining parts, by being inflated, appear like so many distinct Canals. The Third Pair goes through a hole appropriated to it, where there is no Sphenoid Fissure, either singly, or in company with some of the other Nerves of the Eye, and is distributed as in Man. The Fourth, also, is as in Man. The Fifth, as in the Human Species, is also divided mto three Branches, and these are larger or smaller, according to the form of the different parts of the Face. In Carnivorous Animals, as the Tiger, the second and third portions of this Nerve appear to be uncommonly large. The Sixth Pair, as in the Human Body, is bathed in Blood ; and, while in the Cavernous Sinus, it is con- nected by one, two, or more Branches with the Great Sympathetic. The Seventh, as in Man, divides into the Portio Dura and Portio Mollis. The former differs according to the form and extent of the different parts of the Face upon which it is dispersed. The Portio Mollis, as in Man, is entirely spent in the Labyrinth of the Ear. The Eighth and Ninth are dispersed nearly as in Man. The Great Sympathetic Nerve has nearly the same connection in the Cranium with the Fifth and Sixth Pairs, the same connection in its course with the Nerves near it, and forms the same kind of Ganglia, as in Man; only varying a little in the number of Filaments sent off, or in the form of the Ganglia. SPINAL PART IJ OF MAMMALIA. 57 SPINAL MARROW AND VERTEBRAL NERVES. The Spinal Marrow is covered by the same Mem- branes, and divided into two Lateral Cords in the same manner, as in the Human Body. The division into two Lateral Portions is still more distinctly marked than in Man. The number of the Nerves coming off from the Spinal Marrow is equal to that of the holes between the Vertebrae ; and they arise in a similar man- ner as in the Human Subject. The Cervical Nerves are seven in number on each side in Mammalia in general, besides the Occipital and Accessory Nerves. The size and extent of the Branches pf these Nerves vary according to those of the parts to which they give Branches. The Brachial Plexus is produced by the three last Nerves of the Neck, and first of the Back. They consist, as in Man, of a num- ber of large Trunks, variously disposed according to the shape and size of the anterior extremity. The Dia- phragmatic Nerve is quite similar to that in Man. The Dorsal and Lumbar differ only in number from those in the Human Body, and they may be known by attending to the number of the Vertebrae. Of the Pelvic and Caudal Nerves, the former is as in Man, the latter go from the Vertebral Canal, by the Foramina between the first pieces of the Caudal Verte- brae, to be dispersed upon parts at the root of the Tail, and upon the continuation of that substance. The Nerves of the Posterior or Abdominal Extremi- ties form a Plexus, of which the Cords, and their dis- tribution, are nearly as in the Human Species. OF OF THE EYE [PART f - OF THE EYE f A--LL Mammalia have two Eyes. They are largest in proportion in small Animals, excepting in such as live much under ground, as the Mole and Shrew, where they are quite diminutive. In the Ape kind, their direction is forward as in Man, but they are closer together. In other Quadrupeds, they are placed laterally, and proportionally more dis- tant from each other. In Man, and in the Ape tribe, the axis and diameter are nearly equal to each other. In the greater number of Quadrupeds, the axis is rather less than tlxe dia- meter. In the Cetacea, it is found to be nearly as two to three. Eye-lids are common to all the Animals of the class, but the under one, in most Quadrupeds, wants Cilia. In most of the Ape tribe, in the Elephant, &c. they are present in both Eye-lids. The Sebaceous Follicles are very distinct in the larger Mammalia, as the Ox, &c. The greater number of Quadrupeds have a third Eye- lid, termed Membrana Nictitans, or -Palpebra Tertia yel Interna. It is of a thick substance and crescentjc form, PART L] OF MAMMALIA. 59 form, is placed at the inner corner of the Eye, and va- ries in size as circumstances may require. In many, it js only a partial covering. In the Lion and Cat tribe, Elephant, Seal, &c. it goes over the whole anterior part of the Eye. In Man and Apes, there is only a Rudi- ment of it. In the Cetacea, it is wanting. The Caruncula Lacrymalis is observed in some, as the hooved Animals j but in others, it appears to be wanting. The Lacrymal Gland exists in all the Animals of the class, and has nearly the same situation as in Man. In some, as the Ruminants, it is divided into Lobes. In the Hare and Rabbit, it is so large as to cover a great part of the Eye. The Ducts of this Gland are numerous, and, in larger Quadrupeds, can be readily seen passing through the Upper Eye-lid. Besides the ^Lacrymal Gland, several Quadrupeds have an additional substance, termed Glandula Harderi. Jt^ exists in some of the Glires, in the Carnivora, Rumi~ nants, and Belluce. In Ruminants, it is situated at the inner angle, and discharges a whitish humour, which passes by an orifice under the Palpebra Tertia. The Puncta Lacrymalia are in general the same as in Man. In the Hare, Rabbit, and some others, in place of Puncta, there is a Slit under the Palpebra Tertia, opening into the Lacrymal Duct. In Sheep, the Puncta join into a long Nasal JDuct, which terminates near the bottom of the Nose. Some of the Ruminants, as the Deer and Antelope, are remarkable for the Larmiers, or Fossae Lacrymales, which are small Cavities upon the Cheek under the Eye- lids, 60 OF THE EYE [PART I. \ lids, and communicate by a Groove with the inner angle of the Eye. In the Elephant^ the Lacrymal Organs have not been found ; and in the Cetacea, as in most Animals living constantly in the water, they are wanting. The Tunica Conjunctiva agrees in general with that in Man, varying only a little in colour over the Tunica Sclerotica. The Cornea, in Quadrupeds, is not quite circular, being somewhat wider in a transverse than longitudinal direction. It varies a little in convexity in different Animals, and also in its proportion with respect to the Sclerotica. In all it is composed, as in Man, of trans- parent thin Membranes, closely united. The Iris exhibits great variety in colour in different Animals. Each Species, in the wild state, is observed to have a fixed colour ; but the colour varies in do- mestic Animals, though less than in the Human Spe- cies. These variations are found to correspond, in some measure, with the colour of the Hair $ and in party-coloured Animals, a mixture of colours has been observed in the Iris. A Fibrous structure appears in the Iris of some Animals, as the Or, which DR MONRO thinks, if Muscular, may affect the Pupil. BLUMEN- BACH has not been able to discover true Muscular Fibres even in the Eye of the Elephant and Whale. The motions of the Iris in the whole Animals of this class are involuntary. The form and size of the Pupil correspond with the Animal's manner of life. In the Ape kind, and many Carnivora, it is round as in Man,, In Solipeds, Ruminants, and Cctacea, it is transversely oblong. PART L] OF MAMMALIA. 61 oblong. In the Cat kind, it forms an oval, placed in a vertical direction, and, in a strong light, is contracted almost to a line. The size of the Pupil is in proportion to the quantity of light wanted. Night-watching Ani- mals, as the Cat tribe, have it contracted through the day, and dilated through the night, to receive a suffi- cient quantity of light. In the Foetus, at an early pe- riod of Gestation, the Pupil is covered with a Mem- brana Pupillaris, as in the Human Species. The Sclerotis, in most of the Mammalia, corresponds in texture with that in Man, and, as in the Human Eye, is thinner at the anterior than posterior part. In the Seal) it is thick and firm, but its middle so thin and flexible, as to influence what are termed the Internal Cha?iges of the Eye. In a Whale of ordinary size, where the Eye is only equal to the bulk of an Orange, the Sclerotis is fully an inch thick at its back part, but thinner and more yielding anteriorly, which may in some measure answer the same purpose with the flexibility in the middle of the Sclerotica in the Seal. The Cornea, in the Whale, is received into a Groove of the Sclerotic ; but in the other Animals of this class, there is considerable variety in the attachment of these Coats ; though in all, it appears they can be separated from each other by maceration. The Choroid Coat and Ciliary Processes exist in all the Animals of the class, and both of these parts, as well as the back of the Iris, are generally lined with a Pigment, which, in the Ape kind, is brown or black, as in Man. The Ciliary Processes, and their Vascula- vity, are very conspicuous iu some of the larger Ani- mals 62 OF THE EYE [!*ART I. mals of this class, as the Leopard, Horse, Ox, Whale $ &c. In some of the Glires, as the Hare and Rabbity and in the Carnivora, Solipeds, Ruminants, Bellu<, and the Cetacea, there is a real Pigmentum Nigrum at the fore part of the Eye ; but at the Back and Temporal Side, the colour is brilliant, and is termed Tapetum Lucidum. This is wanting, however, over the entrance of the Optic Nerve. In the Horse, Goat, and Deer, the Ta- petum is of a silver blue, changing into violet. In the Ox, it is green, changing into a sky blue ; in the Sheep, green ; in the Cat kind, Bear, and Dolphin, pale yellow ; in the Badger, Dog, and Fox, it is blue, changing into white. In general, the paint is brightest in night- watching Animals, the brightness reflecting more light upon the Retina. Wherever the Pigmentum exists in the Eye, it is of a black colour where it lines the fore part of the Choroides and back of the Iris. In some entirely white Animals, as the White Rabbit, White Mouse, &c. there is no paint upon the inner side of the Eye 5 in such cases, there is a great degree of redness, owing to the Blood-vessels of the Choroides shining through the Retina and Humours ; where, however, there is the least spot of a dark colour, this is not always observed. The Optic Nerve commonly passes through a Cribri- form part in the bottom of the Eye, and has in gene- ral the same appearance, and same kind of termination, as in the Human Subject. In some Animals, as the Hare and Rabbit, the Nerve goes undivided through ihe Sclerotis and Choroides, and forms a sort of Cup, from PART I.] OF MAMMALIA. 6$ from the edges of which the Retina arises, having' Medullary Fibres in it, and these running chiefly in a transverse direction. The Foramen Centrale, or spot seen in the Retina near the axis of the Human Eye, has been observed in several of the Ape tribe, where the Eyes are placed nearly in the same direction as in Man. The Lens, in all Quadrupeds, is divided into two spherical segments ; the posterior is generally the more- convex of the two. In Man, the Lens is found to be proportionally the least and flattest. Of all other Mammalia, BLUMENBACH found it proportionally the greatest in the Opossum, and the least in the Whale* In some Quadrupeds, it is of a much rounder form than in the Human Body. In the- Cetacea, it is nearly spherical. The proportion of the axis to the diameter has been observed to be, in Man and the Ape tribe, as 1 to 2 ; in the Dog, as 7 to 9 ; in the Horse , as 2 to 3 j in the Ox, as 5 to 8 j and in the Whale, as 13 to 15. The other Humours of the Eye have nothing par- ticular in them. The proportions of the three Hu- xnours, the Aqueous, Crystalline, and Vitreous, mea- sured on the axis of the Eye, are in Man, 5, 4, 15 ; in the Dog, 5, 8, 8 ; in the Horse, 9, 16, 18 ; in the Ox, 5, 14, 18, Of the Muscles of the j^- Those in the Ape kind are the same as in Man. In other Quadrupeds, the Eye has a peculiar Muscle, termed Suspensorius, which may assist the others according to the direction of its Fibres. It arises, with the straight Muscles, from the edge of the Foramen Opticum, and, running between these 6* OF THE EYE [PAR* I. these and the Ball, is fixed to the Sclerotis a little be- hind the insertion of the Recti Muscles. In the Horse and Ruminants, it is in the form of a Funnel ; but in the greater part of Carnivora^ and in the Cetacea, it forms four distinct Muscles. In the Rhinoceros, it is di- vided into two parts ; but, besides these, MR THOMAS of London has discovered, that this Animal has four Ten- dinous Processes, which arise from the inner side of the Sclerotis, at the bottom of the Eye. These spread out and join anteriorly, to form a kind of Muscular Mem- brane, that is inserted into the Choroides at its widest part, and is supposed to be connected with the internal changes of the Eye. In all Mammalia, the Globe of the Eye is surround- ed with Fat, which answers the same purpose as in the Human Body. OF MAMMALIA, 6" OF THE EAR. I HE Organ of Hearing exists in all the Animals of the class, and the External Ear in most of them ; but there are several individuals in which the latter is defi- cient, as those which live much under ground, as the Mole, or in the water, as the Ornithorrynchus, most Seals, the Walrus, Manati, and the Cetacea, The es- sential parts are in general as in Man, varying chiefly in form, and in all adapted to their manner of life. The Lobe is wanting in all the Quadrupeds. An Au- ricle, resembling that in Man, is only met with in some of the Ape kindj though a Concha, or External Ear$ exists in Quadrupeds in general j but even in the Ow* rang-outang, as well as in other Apes 9 it is more point- ed than in Man. The External Ear varies much in its general appear- ance, direction, and composition. Timid, and also nocturnal Animals, as the Hare, Deer, Bat, &c. are observed by Naturalists to have large Ears, to add to their acuteness of hearing, and enable them to guard against beasts of prey. The Concha is found to be turned backward in those that fly, as the Hare, and Vox, IV. E forward 66 OF THE EAR [PART I. forward in such as pursue, as the Lion, &c. Or in some, the superior part of the Concha is turned down, as in the Spaniel, Sheep, Hog, Elephant, &c. which en- ables them to hear sounds from below. Pendant Ears are considered by some Naturalists as marks of slavery. In the Bat, the Concha is so constructed, as to pre- vent the Air from rushing violently in while the Animal is flying. The External Ear, in Quadrupeds, is more conical, and more uniform internally, than in Man. In all the class, excepting some of the Ape tribe, the outer bar of the Ear, or Helix, is wanting, the part being thin, and sharp on the edges ; and instead of an Antihelix, there is a transverse eminence, situated deep in the Ear. There is a Tragus and Antitragus, the Jatter of which, in 'some Animals, as the Shrew, serves as an Operculum to the Ear. In Animals with very long and moveable Ears, the Muscles are much more numerous than in Man. In the Dog, Horse, Sheep, &c. they are from a dozen to twenty in number to each Ear. Some arise from the Head, and are fixed to the part at the root of the Concha of the Ear, termed Scutum; others come likewise from the Head> and are inserted into the Concha or Meatus Externus ; some pass from the Scutum to the Concha, and some from one part of the Concha to another. By means of these Muscles, the Animal can commonly move the Ear in every direction, or turn it upon its own axis, without moving the Head. All Adult Quadrupeds have the Meatus Externus- osseous at its inner part ; but it varies in length, width > and direction, in different Species. In some, it is cy- lindrical -, PART L] OF MAMMALIA. 67 lindrical ; in others, flattened ; in Apcs> it is nearly as in Man ; in Carnivora and Ru?ni?iants t it passes di- rectly inwards ; in some, as the Otter and Pole-cat, it goes in a retrograde direction ; in the Rodentia, it is directed downwards ; in the Mole 9 where it is quite flat, it has the Membrana Tympani laid over it like a roof; in the Elephant and Horse 9 it goes downwards and backwards. In some Animals which dive in the water, it is pro- vided with a Valve, as in the case of the Water S/?mr, and some Whales. In the Cetacea, the Osseous Canal, like the External Auricle, is wanting ; in place of which there is a Cartilaginous Tube, which begins by an ori- fice proportionally very minute, on the surface of the Skin, and leads in a winding direction through the Fat, till it terminates at the Membrana Tympani. In the OrnithorrynchuSy also, the Meatus is observed to be long and tortuous. The Membrana Tympani, the Tympanum, and the Eustachian Tube, are found to be common to all Mam- malia ; and the Membrane of the Tympanum appears to be concave externally in all the individuals of the class, the Cetacea not excepted. Its structure nearly re- sembles that in the Human Body. It is fixed in a case of Bone, which is commonly open above, and is some- what of an oval form, with the long diameter placed in, a vertical, or in an oblique direction, though it varies in this last respect considerably in different Animals. The Tympanum differs in size, form, and situation. It is oval in some, round or hemispherical in others* E 2 and 68 OF THE EAR [PART I. and in several it is angulated ; or is sometimes so shal- low as to be in form of a chink. In the Ape tribe, there are scarcely any Mastoid Cells to communicate with the Tympanum, the Pro- cess containing these, in the Human Body, being in this race of Animals almost obliterated ; but, in place of Mastoid Cells, there are others which extend a con- siderable way into the Temporal Bone. In the greater part of digitated Mammalia, instead of a Mastoid Process, there is a Bony Organ, commu- nicating with the proper Tympanum, which, in the greater part of the Glires and Carnivora, forms a large Cavity, or Bidla Ossea, that makes the principal part of the Tympanum. This, in the Dog, Cat, Lion, Ti- ger, &c. is globose -, in Ruminants, it is angular ; in the Bear, it is wanting. In the Solipeds, Ruminants, Pigs, &c. the Cavity is divided into Cells, and there is behind this a long Process, like the Mastoid, or in some like the Styloid, but belonging to the Occipital Bone. In some Animals, as the Indian Hog, Marmot, and Porcupine, the walls of the Tympanum shew vestiges of Cells ; but the Cellular appearance is more distinct in the Elephant,, where this Cavity is of great size. The Tympanum, with its Bulla Ossea, in the Ceta- cea, is formed of a Bony Lamina, rolled on itself like a Concha ; but there is no spiral Cavity in it, the sub- stance being quite solid and hard like a rock. This has been frequently mistaken for the Labyrinth in these Animals. The Internal Parts of the Ear, in the Whale tribe, are PART!.] OF MAMMALIA. 69 are not connected to the Bones of the Cranium, as in other Mammalia, but are loosely attached by Liga- ments. The Eustachian Tube, in Mammalia, has nearly the same kind of structure and openings as in Man. In the Horse, it communicates with a large Sac, placed in the lateral and posterior part of the Mouth. In the Cetacea, it is of great size, and terminates at the Nose 91* Blowing Hole, where there is a Valve to prevent the water from rushing into it when thrown out by this opening. The Qssicula Auditus are the same in number in al- most all Mammalia, but they vary much in form and size in the different Species. In some Quadrupeds, as the Mole, Marmot, and Guinea Pig, a Process is found, which extends from one side of the Fenestrk Ovalis to the other, and passes between the Crura of the Stapes, so that, when the Stapes is removed, there appears to be two Fenestra3 Ovales. In the Whale, that Bone has very nearly an entire Plate, instead of two Crurai In some of the Bisulca, one or two additional Bones are occasionally found. The Ornithorrynchus, on the contrary, has only two Ossicula, the second of which approaches in its form to the single Bone in Birds, (see Phil. Trans. 1805.) The Muscles of the Internal Ear of Mammiferous A- nimals appear to be nearly the same as in Man. The figure and size of the Fenestra Rotunda, and Fenestra Ovalis, are found to vary considerably. In some, as the Bear, the Cochlear Foramen is triangular ; o OF THE EAR [PART!, in others, as the Ant-eater, both the Foramina are oval, and nearly equal in size. In Carnivora, Soiipeds, Ru- minants, and Cctacca, the Cochlea r Foramen is the largest ; in some, it is double or triple the size. In the Hare and Opossum, the Vcstibular Opening is by much the largest. In all Mammalia, the two Foramina are filled, the Cochlear with Membrane, and the Vestibular with Bone. The Labyrinth is nearly similar to that in Man, but the proportional size varies much among the different Species, As in the Human Subject, also, it is com- monly hollowed out in the Pars Petrosa-, but in some, as the Hat and Mole, it is visible in the Cranium with- out any preparation. In some, it is large; in others, small. The Cochlea is almost always turbinated, and the number of turns are commonly the same in the dif- ferent individuals, excepting a few, as the Guinea Pig, Porcupine, and Indian Hog, where there is a turn more, and the Cetacea, where there is a turn less, than in Man. In most Carnivora, and in the Horse, Hog, and Elephant, the Cochlea is larger in proportion to the semicircular Canals than in. Man. In Rats, it is re- markably large, compared with the Canals. The size of the two Canals of the Cochlea is in general nearly equal , but in some, as the Dog, Horse, and Elephant, the Scala Tympani is the larger. In the Celacea, the semicircular Canals are proportionally so small, that by some they have been overlooked, and by others, as, PR CAMPER, their existence has been denied. PAKT!.] OF MAMMALIA. 71 The Vessels and Nerves of the Ear are in propor- tion to the parts on which they are dispersed. They do not differ materially from those in the Human Body. In Mammalia, as well as in Man, the Portio Mollis passes, with the Portio Dura, into the Meatus Internus, and enters the Labyrinth by several Holes, the number and size of which vary in different A- iii Dials. OF 72 OF THE -NOSE [PART I. OF THE NOSE, JT HE Nose, in Mammalia, corresponds with that in Man, hi communicating with the Fauces, and conduct- ing the air to the Lungs ; but differs from it in form and size, in the Sinuses and Laminae which increase the extent of the Nasal Cavity, and in the Cartilages which cover the aperture of the Nose. The Sinuses of the Head, all of which lead directly or indirectly into the Cavity of the Nose by small aper- tures, differ considerably in shape, size, and general appearance. They are peculiar to Man and Quadru- peds, and are not fully expanded till the Animal arrives at its full size. Frontal Sinuses. These, in some of the Ape tribe, are large ; in others, inferior in size. Among some of the Glfrcs, as the Rat and Hare, they are wanting ; but in some of the Fer the parts moist. The Blood-vessels are from similar Trunks with those in Man. The Nerves arise from the first and fifth pairs also, as in the Human Body. The Olfactory Nerves penetrate the Ethmoid Bone by Fibrillse, corresponding in number and size to the Foramina in the Cribriform Plate, and are dispersed upon the Mucous Membrane covering the Cells and Anterior Conchas of this Bone, and upon the parti- tion of the Nose. Some of these are soft and pulpy ; others, as in the Ox and Sheep, can be readily traced. The Branches of the fifth pair belonging to the Nose, are from the Ophthalmic and Superior Maxillary Portions. Of the first, some minute Branches penetrate the Superior Orbitar Plate, to be dispersed- upon the Membrane lining the Frontal Sinuses ; others go to the Nose, re-enter the Cranium, and return to the Pituitary Membrane, as in Man. The Superior Maxillary Nerve supplies the inferior-posterior parts of the Nose, and sends Twigs to the Maxillary Sinuses much after the same manner as in the Human Species, allowance always be- ing made for the size and form of the Organ in different Animals. Trunk or Proboscis- of the Elephant. This very sin- gular Organ is extended into a long fleshy substance of a conical form, fixed by its base to the Frontal and Intermaxillary Bones. It contains two Tubes a little before its axis, which form 78 OF THE NOSE [PART I. form the prolongations and external openings of the Nose. These are nearly cylindrical, but contracted at their extremities, particularly next the Head, where they are twice inflected upon the Intermaxillary Bones, and fixed round the Osseous Nares. This part is pro- tected by the Cartilage of the Nose, which is of an oval form, and so much more convex in the Male than the Female, that by this it is said the sex can be distin- guished. The Tubes are covered with a strong Tendinous Membrane, and perforated by many Mucous Follicles, which open into their Cavities. They are separated from each other, and are both surrounded by a quanti- ty of white Adipose Substance, which also extends be- tween the different Muscles that occupy the space be- tween the Tubes and the Skin, and which have been already described. The outer part is covered by the Common Integuments, which are lined with a Tendi- nous Membrane and Cellular Substance. The Probos- cis serves to pump up the drink the Animal takes in ; but, according to CUVIER, the Tubes want that deli- cate structure internally, which is necessary for the Or- gan of smell ; so that, in his opinion, this sense in the Elephant is confined to the part of the Nostrils contain- ed in the Bones of the Head. In the Cetacea, the Nares and Spiracula differ much from the Organ of smell in other Mammalia, being placed on the summit of the Head, and serving as pas- sages of respiration, and for the rejection of the water which enters the Mouth along with their Food. The two Osseous Nares are placed so high on the Head, that PART I.] OF MAMMALIA. 79 that the Animal can breathe while the Mouth is under water. They are furnished with two semicircular fleshy Valves, which are shut by a strong Muscle. On the upper side of the Valves are two Membranous Sacs, lined with a black Mucous Skin, which is the continufttion of the Common Integuments, and covered externally by a strong Muscular Expansion that arises from the Cranium. They have a common opening ex- ternally, by a narrow chink in form of a crescent. The water taken in by the Mouth, and which, in Fishes, is thrown out at the openings of the Gills, is here pre- vented from being swallowed by the contraction of the Pharynx. This elevates the Valves, and distends the Sacs, from which the Fluid is forcibly discharged to a great height by the surrounding Muscular Fibres. QF 80 OF THE MOUTH, &c. [PART L OF THE MOUTH AND THROAT, WITH THEIR APPENDICES. LIPS. I HE Lips, or Fleshy moveable parts exclusive of the Jaws, are' found to be peculiar to Man and Quadru- peds ; the Cetaceous tribe have none. Quadrupeds, the Ape tribe not excepted, have fewer Muscles in the Lips than are met with in the Human Species ; of course, they have less variety in their mo- tions. Where the Nose is prolonged into a Snout, as in the Pig and the Elephant) there is scarcely any Up- per Lip; the Muscles which, in other Animals, be- long to the Upper Lip, are here employed in moving the Nose. In those which want Teeth in the Upper Jaw, the Gums are harder than in others, to compensate for this. TONGUE. The Tongue, in all Mammalia, is fleshy and flexible, and, in the different individuals of this class, varies chieflv PART I.] OF MAMMALIA. 81 chiefly in the extensibility of its fore or loose part. In some Animals, as the Ant-eater, Armadillo, and Orni- thorrynchuS) the Tongue is the longest in all the Mam- malia, for seizing their prey. In the Cetacea, on the contrary, it is almost entirely fixed down to the Jaw ; but in Quadrupeds in general, it is nearly as loose as in the Human Body. In some Animals, it serves as an Organ of taste j in others, it is also employed for taking in the Food. In most Quadrupeds, it is proportionally longer and narrower than in Man, and possesses the same kind of Papillae, the chief difference being in their form. In the generality of Herbivora, especially the Pecora, the Tongue is covered with a firm Cuticle, forming in- numerable sharp-pointed Papillae, directed towards the Throat. These, like so many tenter-hooks, assist in laying hold of the grass, and other kinds of Food, and serve, at the same time, to increase the Organ of taste. In some of the Monkey tribe, the Papilhe Maxima? are fewer in number, and differently disposed from those in Man. In the Ferce, the Tongue differs little from that in the Human Body. In the Cat kind, besides many round and conical Papillae, there is a horny or prickly set covering the Tongue, which render it rougher, and enable it to take a firmer hold of the prey. The Dog has, upon the Mouth and root of the Tongue, many Papillae, placed obliquely backwards, which assist in preventing the Food from escaping. There is likewise, in this Animal, a Tendinous Cord, termed Worm, in the under part of the substance of VOL. IV, F the 82 OF THE MOUTH, &c. [PART I. the Tongue, which extends as far as the point, and is inclosed in a Membranous Sheath. It is supposed to assist the Animal in lapping its drink, and is found in the Opossum, which drinks in a similar manner. The removal of this substance from the Tongue of the Dog, has been long considered as a preventive against Hy- drophobia. In Solipedsy the Papillae Conicse of the Tongue are small and compact ; the Fungiform are only found in the sides of this Organ, the space behind resembling that in Man. In most Pecora, as the Ox, &c. the Papillae Conicse, covering the fore part of the Tongue, terminate each in a horny flexible Filament, turned backwards, assist- ing, as in the Tongue of many other Animals, to lay hold of the Food. The posterior part of the Tongue is covered with Tuberculated Papillae, which, in some individuals, are numerous. Among the Cetaceous tribe, the Tongue in the Dol- phin has no distinct Conical Papillae. SALIVARY GLANDS. The Salivary Glands are found to exist in almost all Mammalia ; their situation and structure being nearly as in Man. They differ only in shape, in proportional size, in colour, and in the direction of their Excretory Ducts. They are observed to be small in the Ferae, where there is little mastication, larger in the Glires, and largest of all in Solipeds and Ruminants, which grind their Food. In PART I.] OF MAMMALIA. 83 In the Ape kind, the Parotid Gland is remarkably large, and here the Maxillary and Sublingual open each by a distinct Duct at the Fraenum Linguae. The Parotid exists in all Quadrupeds, except in some of the Ant-eaters, and the Seal. In the former Ani- mals, the want is supplied by the Maxillary, which ap- pears to be increased in size. In the Seal) the Sublin* guaJ is wanting, as well as the Parotid. In the Glires, the Salivary Glands are of consider- able size. The Parotid, in the Rabbit, embraces the Concha of the Ear, and extends as far as the Maxillary Gland. The Parotid Duct, in the Glires, crosses the upper part of the Masseter, and perforates the Mouth opposite the last superior Molaris. The Duct of the Maxillary has no Papilla at its termination upon the side of the Fraenum Linguae. In some of the Porcupine Ant-eaters^ the Parotid is smaller than the Maxillary ; the latter is extended in the Neck. The Sublingual is long and narrow, and the Molar Glands are united into a mass under the Buccinator. The Salivary Glands, in the Carnivora, are smaller than in the Glires, little mastication being required by this set of Animals. The Parotid is commonly not larger than the Maxillary, and is often of an inferior size, as in the Dog. In this Animal, and in the Cat % the Parotid is of a crescentic form, and embraces the Concha of the Ear, extending as far as the Maxillary Gland. In the Cat, the Sublingual Gland is wanting, F2 84 OF THE MOUTH, &c. [PART L and in the Dog, appears little more than a prolongation of the Maxillary. The Amphibious Quadrupeds which are of the Car- nivorous kind, have the Salivary Glands proportionally very small. In the Seal, as already noticed, there are no Parotids nor Sublinguals ; but there are two Maxil- laries. a great and a small, the common Duct of which opens in the ordinary place. In Solipeds, the Salivary Glands are of great size, and have a lobulated appearance. In the Horse, the Parotids are very large, and, extending above and behind the Concha, go beyond the angle of the Jaw -, the Duct runs by the under part of the Masseter, and opens upon a Papilla opposite to the Fourth Mo- laris of the Upper Jaw. The Maxillary Gland extends along the side of the Larynx and Pharynx, having also a Papilla where the Duct opens at the side of the Fraenum Linguae. The Snblingual Gland opens by many small orifices arranged along the under part of the side of th Tongue. In Ruminants, also, the Salivary Glands are of great size. In the Ox and Sheep, the Parotid Duct passes by the inferior part of the Masseter, and perforates the Cheek opposite to the second and third Superior Mo- lares. The Maxillary is remarkably long here, and extends,, as in the Horse, along the Larynx and Pharynx, hav- ing a Papillary Valve at its termination. The Sublin- gual is very long in these Animals, has a single Duct which PART I.] OF MAMMALIA. 85 which runs by the side of the Inferior Maxillary, and opens upon a Papilla near the termination of the latter. In the Hog among the Belluce, there are two Sublin- guals on each side, one anterior to the other ; the pos- terior, which is narrow and Very long, is placed on the outer side *f the Maxillary, extending from the angle of the Jaw to the Anterior Sublingual, and sends out a single Duct, which terminates at a little distance from the end of the Maxillary Duct. The Anterior Gland perforates the Mouth by several openings in a range. In the Cetaceciy the Salivary Glands appear to be wanting. foramen Incisivum, or Ductus Incisivus. This ap- pears in all Quadrupeds, but varies considerably in size in different Genera. In the Ape, it is simple below, but opening into each Nostril above. In Carnivora, SoUpeds, Ruminants, &c. it is double, and forms a com* munication between the Mouth and each Nostril, by which fluids pass from the one cavity to the other. THROAT. Velum Palati.' This, in Quadrupeds, is in general similar to that in Man, only it is proportionally larger. Except in the Ape> it does not send out any prolonga- tion in the form of an Uvula. In the Elephant, it de- scends under the Epiglottis, in consequence of which, liquors pumped up can be received from the Proboscis without getting into the Larynx. F3 In 86 OF THE MOUTH, &c. [PART I. In the Cefacca, the Velum is changed into a Canal, by which the Posterior Nares are prolonged about the pyramid of the Larynx, and their posterior part conti- nued with the Pharynx. Pharynx. The Pharynx, in Mammalia in general, lias nearly the same structure as in Man, but stronger on account of the necessary force required in their ho- rizontal situation. It exists in all Vertebral Animals, but particularly in Mammalia. In many, as the Ele- phant, Bear, c. there is a proper Pharyngeal Muscle, which is merely a continuation of the Muscular Coat of the Esophagus. Bursa Faucium. Many Species of the Ape, and also of the Marmot) are provided with Glandular Sacs, or Cheek Pouches, termed Burses Faucium, placed behind the Palate, and serving as a temporary reservoir for the Food. The Camel has this structure also, which is supposed to be for containing fluids to lubricate the Throat in the sandy deserts. The Omithorrynchus is also found to have Cheek Pouches. In the Cetacea, the Pharynx is separated into two by the Larynx, which forms a pyramid that can rise as high as the Posterior Nares, and, by entering these, can allow the Aliment to pass by each side of it to the Esophagus. There is also a particular Canal which rises from the Pharynx, and is attached to the margin of the Posterior Nares, or Blowing Holes. The cir- cular Fibres of this Canal form a Sphincter, which, by .contracting round the Pyramid, cuts off the communi- cation, PART!.] OF MAMMALIA. 87 cation between the Blowing Holes, Mouth, and Pha- rynx. Esophagus. In all the class, the Esophagus is nearly cylindrical, and is continued from the Pharynx to the Stomach. It is long in all, except in the Cetacea. It is narrow in most, but wide in Animals which swallow vo- raciously. In the generality of Quadrupeds, the Esophagus is distinguished from that in Man, by two rows of Mus- cular Fibres decussating each other, and running in a spiral but opposite direction. On this, Rumination is commonly explained, though the same structure exists in different Carnivorous Animals which do not rumi- nate, as the Dog, Cat, Bear, &c. ; but in ruminating Animals, the Coats of the Esophagus are remarkably strong. Many Plicae are formed upon the inner surface of the Esophagus, which, as in Man, are most evident when it is most contracted. There are also many Fol- licles here, from which a Humour is plentifully sup- plied. OF THE TEETH. All Mammiferous Animals have Teeth in their Jaws, with a few exceptions, as the American Ant- eaters, Scaly Lizards, and the proper Whales. Be- sides the Teeth proper for mastication, some, as the Dog, I^ion, Tiger, &c. have Canine Teeth, serving partly as offensive weapons, and partly to enable the Animal to lay hold .of and lacerate its prey. Others, as the Elephant, Hippopotamus, and Walrus, have T- * Tusks, 88 OF THE MOUTH, &c. [PART I. Tusks, serving chiefly for offensive or defensive wea- pons. In the Seal and the Cetacca, all the Teeth are of the same form, and answer merely the purpose of seizing the Food. The Tusks, or Defences, of the Elephant, Wal- rus, and Narwal, are incrusted over with a substance harder than the body of the Tusk, but softer than Enamel. The Osseous substance composing these Tusks, which, in the class Belluae in general, and some of the Whale tribe, forms the Ivory, differs from that of other Teeth, in being of a harder and denser texture. The Ivory of the Elephant's Tusk is distin- guished from that of all others by the Curvilinear Lo- zenges which appear very distinct in the polished trans- verse section of a Tusk. The Ivory of this Animal is softer than that of others, and acquires a yellow hue by exposure to the air. That of the Hippopotamus is harder and whiter than the former, and preferred by Dentists in the making of artificial Teeth. The most remarkable Teeth are those of the Cape Ant-eater, which are formed of cylinders composed of Small Tubes, shut at the triturating surfaces, and, when cut transversely, appearing like a section of a Cane. The Teeth of the Ornithorrynchus are observed to have a similar structure. The Bodies of Teeth, in some Animals, have a par- ticular colour, as in the Squirrel, Beaver, &c. where they are brown anteriorly -, and in several Pecora, where the Molares are covered by a hard black substance of a glassy appearance. la the Ox and Sheep, it is of a bronze colour. The PART L] OF MAMMALIA. S<> The Front Teeth of the Upper Jaw are fixed in the Intermaxillary Bone, which includes also the Tusks of the Elephant, Walrus, and Narwal. The number and form of the Teeth varies considera- bly in different Mammalia. In the Glires, the cutting edges of the Incisores are in the form of a Chizel. The Teeth of some Animals, as the Glires, are co- vered with Enamel only on their anterior surface, but this is continued along the roots ; hence, as the Osseous part wears down sooner than the Enamel, the Animal is still capable of gnawing hard substances. The Teeth of the Glires, the Tusks of the Elephant and Hippopotamus, and others of a similar nature, are in a constant state of growth, in consequence of a Pulpy Vascular Substance within them, upon which the Os- seous part of the Tooth is formed ; so that the interior part of the Tooth advances to supply the portion worn down. The Teeth of the Lower Jaw of some of the Ani- mals of this order, as the Squirrel, Rat, and Beaver, are remarkable for the length of their roots, which nearly equals that of the Jaw itself, though a small por- tion only appears beyond the Gums. They are curved back under the roots of the Grinders, and sometimes go as far as the Coronoid Processes. The Tusk of the Narwal occupies the place of an Incisor, and is almost constantly found single, the other one being either early destroyed, or lurking in the .Jaw. The Canine Teeth of the Upper Jaw, in Mammalia, are 90 OF THE MOUTH, &c. [PART L are placed close to the Intermaxillary Bones, and differ more in the different Genera than either the Incisores or Molares. In many of the Ape kind, and more espe- cially in the larger Carnivorous Animals, as the Lion or Tiger, the Canine Teeth are of great size ; and in some of the Swine tribe, as the Babiroussa, they ap- proach so near to a circle, as to render them ill adapted to the purposes to which they are applied at an early time of life. The Molares exist in every Animal possessing Teeth, the Narwal excepted, which has only the long Tusk. The situation and appearance of the Grinding Teeth vary considerably in this class of Animals. In the Fera, the Bodies of these Teeth are entirely covered with Enamel ; and the same thing takes place in the Animal called Mammoth, or Carnivorous Elephant ,- while the Grinders of Quadrupeds living chiefly on vegetables, and the Incisores of the Horse, have plates of Enamel extending into the substance of the Tooth, and mixed in a tortuous manner with the Osseous part. These Animals have, besides, an additional substance in their Molar Teeth, differing in its nature from the two others, being like Tartar, and termed by DR BLAKE, Crusta Petrosa, and by CUVIER, Cement. This may be readily seen either in a longitudinal or transverse sec- tion of the Tooth of a Horse or Ox, but still better in the Tooth of an Elephant, where it forms a large pro- portion of the mass. It is then distinguished by the greater degree of yel- lowness and opacity of its colour, and is considered by the PART IJ OF MAMMALIA. 91 the two Authors mentioned above, as being originally deposited by the Capsule which forms the Enamel. It fills the interstices on the surface of the different layers of the Enamel, and unites the layers together. It is the softest of the three component parts of the Tooth, and is more readily affected by acids and fire than the Osseous substance. It is sometimes, as in the Cptu, Sheep, &c. not completely formed in the centre of the Tooth, in consequence of which Cavities are left, which become filled with extraneous matter. The Enamel in the centre of the Incisores of the Horse has no Crusta Petrosa, but is filled with blackish Tartar, which extends only a short way into the Tooth, of course soon disappears, in consequence of mastica- tion. This is termed by Farriers the filling up of the Teeth, or rather Mark of the Mouth, and forms a cri- terion of the Animal's age. In many Animals which do not ruminate, as Solipeds and the Elephant, the Bodies or Crowns of the Mola- res have their grinding surfaces placed nearly in a hori- zontal direction. In Ruminants, their surface is some- what oblique, the outer margin of the Upper, and the inner margin of the Under Tooth, being the most pro- minent. In the greatest part of the Fcrte, especially of the Dog and Tiger kind, where the Molares are of an irre- gular wedge shape, the lower ones close within the up- per, and act like scissars. All the three sets of Teeth exist in the Ape tribe, in Carnivora, in Solipeds, and in Ruminants naturally des- titute 92 OF THE MOUTH, Sec. [PART I. titute of horns, and in the BeHncc, except the Elephant and two-horned Rhinoceros; but in the Human Species only are the three sets disposed in an uninterrupted se- ries, and the Teeth of one Jaw placed at an early age directly opposite those of the other. The Fore Teeth of the Upper Jaw are wanting in Horned Cattle, and also the Canine, except the Stag^ which has rudiments of the latter, and the Musk* which has two very long curved Tusks in the Upper Jaw. The Canine Teeth are wanting in the 'Glires* In Carnivora, and such other Quadrupeds as have the Canine longer than the other Teeth, there are va- cancies in each Jaw for lodging the corresponding Ca- nini of the opposite Jaw. In many Quadrupeds, a large vacancy is likewise left between the Incisors and Grinders, in the middle of which, in the Horse> a small Tusk is found in the Male, though seldom in the Female. The Elephant has Grinders in each Jaw, and two immense Tusks, termed Defences, in the Upper Jaw, but no other Teeth. The Tusks are placed with the concave side upward, and belong chiefly to the Male. MR CORSE found, that in general they are so small in the Female, as not to pass the margin of the Lip. The Dolphin and Porpoise have small conical Teeth, all of equal size, arranged in a line in both Jaws, and serving merely for securing the Food. The Physeter, or Spermaceti W7iale 9 has these in the Lower Jaw only. In the Nwwal, or Unicorn Fish 9 there FART I.] OF MAMMALIA. 93 there are no other Teeth than the two long Tusks fixed In the anterior extremity of the Upper Jaw. In the Genus Balena, or Proper Whale, the sub- stance termed Whale-bone, covering the Palatine Sur- face of the Upper Jaw, supplies the place of Teeth. It forms numerous parallel plates, which are placed across the Jaw, and descend vertically into the Mouth. They are connected to the Jaw by a Ligamentous Substance, and send, from their opposite edges, fringes of long Fibres, which cover the whole surface of the Jaw. The composition of this substance is found to be nearly the same with that of Horn, Hair, &c. The Whaie-bone is considered by Naturalists as serving to retain the A- mmal's prey. In the Ornithorrynchus Paradoxus, there are a few Horny Teeth fixed to the Gum. There are also Teeth of a similar nature fixed to the root of the Tongue and top of the Throat, which may prevent the Food from escaping till properly masticated. CHANGES OF THE TEETH. In the Ape tribe, as in Man, there are no small Mo- lares among the Deciduous Teeth, but, instead of these, two large Molares in each side of both Jaws. The Permanent Teeth, in Quadrupeds, are observed to be formed as in Man, within Capsules ; and they lie in Cavities near the roots of the Temporary Teeth, and get into the vacancies which these leave when they drop from the 94. OF THE MOUTH, &c. [TART t the Head. The changes of the Teeth have been most attended to in the Plorse. According to the observa- tion of Farriers and others, the Milk Incisors appear at the beginning of the third week after birth. The four middle of these* termed the Pincers, fall in the 30th month, the four following in the 42d, and the four external, or Corner Teeth, in the 54th. The Per- manent Corner Teeth do not grow so soon as the other Incisors ; and when they appear, they scarcely project beyond the Jaw. The hollow in the middle of the Incisors, filled with blackish Tartar, is worn off by use between the fourth and eighth year, after which it is entirely effaced. In the Corner Teeth it remains longer, in consequence of which the Animal's age can generally be known with considerable accuracy. After this period, the age is only judged of by the length of the Incisors, which are in a constant state of growth. Of the Molares, the two first in each Jaw appear at the end of the first week, the following at the end of the third, and the small Anterior Molaris between the fifth and sixth week. The first back Molaris appears near the end of the first year, the second near that of the second year. Be- tween the second and third year, the first Milk Molares fall, the third drops in three years ; and it is not till five or six years, that the last Molaris appears. The Temporary Molares are distinguished by being longer from before backwards than the permanent set. In Ruminants, there are three Milk Molares, which are PART I.] OF MAMMALIA. 9S are replaced by three others, and three Permanent Mo- lares. The Milk Molares are distinguished from the permanent set, by being longer from before backward than in a transverse direction. The age of the Sheep is known by the replacing of the Incisors. In the Asiatic Elephant, the Temporary Tusks drop out in twelve or thirteen months, and are succeeded by the Permanent Tusks, which continue growing through life. The Molares appear in the second week after birth ; they are succeeded by the second in the second year ; the third succeed in the sixth year ; the fourth in the ninth year -, others follow, but their epochs are not known. The succession in the Molares of the Elephant is particularly observed by MR CORSE, (Phil. Trans. 1799.) There is never more than one Grinder, and part of an- other, seen through the Gum. The Body of the ante- rior one is gradually worn away by mastication ; the rest of the Tooth is carried off by absorption, the pos- terior Tooth coming forward to supply its place. The same Processes are found to be repeated at least eight times, and each new Grinder is larger than the for- mer. The first, or Milk Grinder, is composed of four se- parate plates, or partial Teeth, which gradually unite, and cut the Gum between the first and second week after birth. Each succeeding Grinder has an additional number of plates, the last having in all about twenty. It, is observed, besides, that every new Grinder takes a year or more than the former for its formation. From the 96 OF THE MOUTH, &c. [PART I. the slow manner in which the Tooth advances, a small portion of it only appears beyond the Gums, the rest of it being concealed within the Jaw. The Tooth is completed, therefore, first at its anterior part ; and by the time the posterior part appears through the Gum, and is fully formed, the anterior is worn off by masti- cation, so that an Elephant's Tooth can never be ob- tained in a perfect state. Something of the same kind happens in the Grinders of Herbivorous Animals ; when the Bodies of these are quite entire, the roots are not fully formed ; and when these are complete, the Grinders are worn down. A similar succession, but to a less degree, has been observed to take place in the Sits Ethiopicus, or Wild Boar, (Phil. Trans. 1801.) Number PART I.] OF MAMMALIA* Number of tlie Teeth in each side of each Jte, in a few of the different Genera of Mammalia. GENERA. 1 y c d, CO Inf. Incisores. 'c '1 w d, to !s c w J c ( 1 i i CO Inf. Molares. Some Apes, 2 2 1 1 5 5 Other Apes, 2 2 1 1 6 6 Bat, 2 3 1 1 4.5 5.6 Rat, 1 1 3 3 Hare, 1 1 5 5 Mole, 3 4 1 1 7 6 Bear, 3 3 1 1 5 5 Wolf, Dog, Wolf, Fox, - 3 3 1 1 6 7 Cat, 3 3 1 1 3.4 3 Otter, 3 3 1 1 4.5 5.6 Solipeds, 6 6 1 6 6 Camel, 1 3 1.2 1.2 5 5 Musk and some Deer, 4 1 6 6 Other Deer, and Rumi- nants with hollow horns-, 4 6 6 Pig, - - 3 3 1 1 7 7 Elephant, 1 1.2 1.2 Voi. IV. OF THE HEART, &c. [PART L OF THE HEART AND BLOOD- VESSELS. 1 HE Heart has the same general appearance in all Mammalia as in the Human Body, varying only a little in some particulars. A Pericardium belongs to every individual in the class, but, on account of the manner in which the Heart is situated, it has less connection with the Dia- phragm. The form of the Heart in the Ape, Horse, and CXr, is that of an obtuse Cone -, in other Quadrupeds, it is either rounded, or short and wide, or long and narrow, or notched at the point. In the Ourang-outang, the Heart possesses nearly the same obliquity, and rests on the Diaphragm nearly in the same manner as in Man. The rest of the Monkey tribe have the point only touching the Diaphragm, and turn- ing a little to the left. In other Quadrupeds, the Heart is placed in a longitudinal direction, and rests upon the Sternum, the point touching the Diaphragm in some, and placed at a distance from it in others. At the meet- ing of the Venae Cavae in the Right Auricle, a fleshy projection b found, termed Tuberculum LOWEKI, which is not met with in the Human Body. h e PART I.] OF MAMMALIA. 99 The Eustachian Valve is present in some Quadru- peds, and wanting in others. In Adult Quadrupeds, the Foramen Ovale is gene- rally shut, as in Man. In the Amphibious Mammalia, it is commonly shut, though found open occasionally. It is also shut in the Ornithoriynchus, which has four Cavities to the Heart, as well as the Human Species. The Pulmonary Ventricle, in Mammalia, is gene- rally placed more on the right side of the Aortic Ven- tricle than in Man, and is so formed, that when the Heart is cut across, the section of the Left Ventricle is observed to form a circle, and the other an appendix to that circle. The proportional size of the Cavities of the Heart are found to be nearly the same as in Man ; but in the Dolphin, the walls of the Right Ventricle are observed to be nearly as thick as those of the Left, and the Columnse Carneee corresponding. The Left Ventricle differs less in Mammalia than the Right. In some, the Columnse Carneae are more slen- der than in Man ; in others, less in number ; and in a few, the inner side of the Ventricles is almost smooth. The Tricuspid Valve varies in the number of Columns fixing it to the sides of the Ventricle. In some, it has three, as in Man ; in others, four ; in some, only two. The Mitral Valve, in the Lion, Ox, and Sheep, forms large Monticuli, which fix it to the walls of the Ven- tricle. The Semilunar Valves have nothing remarkable in them ; their strength corresponds with the strength and size of the Arteries to which they belong. The Pulmonary Artery differs from that in Man only G 3 m 100 OF THE HEART, &c. [PART!. in the subdivision of its principal Branches, which cor- respond with the number of the Lobes of the Lungs. According to the observations of CUVIER, the sides of the Pulmonary Artery, in the Dolphin and Porpoise^ and probably in the other Cetacea, are as thick as those of the Aorta, as if the Pulmonary Circulation here differed from that in other Animals. In a great number of the individuals of this class, the principal Arteries are quite similar to those in Man, the Branches varying in their distribution according to the variety existing in the parts on which they are dis- persed ; but in others the Aorta, as in Solipeds, Rumi- nants, the Hog, &c. divides, near its origin, into two Trunks of unequal size. The smaller passes forwards, and sends off the Arteries which, in other Animals, come from the Arch of the Aorta ; the other, twice as large as the former, goes backwards, and supplies the place of the Descending Aorta ; hence the names of Anterior and Posterior Aorta are applied to these Ar- teries. In some Animals one, and in others two, common Trunks arise from the Anterior Aorta. This Artery sends off Vessels corresponding with the Subclavians and Carotids, which, in some Animals, arise as in Man ; in others, they are sent off equally in the two sides. In old Rumma?its, and in some other Quadrupeds, as the Hog, two flat Bones are frequently found at the beginning of the Aorta, known by the name of Bone of the Pie art. The Posterior Aorta differs from that i the Human Body, PART!.] OF MAMMALIA. 101 Body, chiefly in the size and distribution of its Branches, corresponding with the division and extent of the In- testines, and the magnitude of the other Abdominal Viscera. Of the peculiarities of the Arteries here, the greatest is that of the Rete Mira&le, found in the greater num- ber of Quadrupeds, particularly among Carnivorous A- nimals and Ruminants. It is situated at th,e sides of the Sella Turcica, and consists of a division of the Internal Carotids within the Head into serpentine Branches, which afterwards uniting, form a Trunk, that divides again nearly as in the Human Body. An uncommon division of the Arteries, also, has lately been observed in some Animals, as the Sloth and Lemur, where the Trunks separate at the top of the Os Humeri and Os Femoris into Branches, which, after descending nearly as far as the Elbow and Knee, re- unite, and are then distributed in the usual way. In some Animals, as the Cctacea, a considerable Plexus of convolutions is found in Arteries of particu- lar parts of the Body, as the Intercostals, Branches from the Subclavians to the Chest, and Branches to the Spinal Marrow and Eye. In many Animals, the common Iliacs are wanting, and there the Aorta divides into two Branches, which supply the place of External Iliacs ; while a common Trunk, from the extremity of the Aorta, sends on the Sacra Media and Arteries analogous to the Internal Iliacs. Sacra Media, in Quadrupeds, 'is generally large, O 3 on 102 OF THE HEART, &c. [PART I. on account of the length of the Tail. In the Seal, and other Amphibious Quadrupeds, a large llio-lumbar Ar- tery from the Aorta sends out the Hypogastric, the Aorta afterwards dividing into two Arteries which cor- respond with the Femorals. Cetaceous Animals, destitute of a proper Pelvis, have the Aorta divided into two portions, which supply the posterior parts of the Body. The Veins have the same general distribution as in Man ; and in some parts, particularly in the Pelvis, they are observed to vary less than the Arteries. The Valves of the Veins correspond in Animals in general, with few exceptions. In some Quadrupeds, as the Horse, DR HALLER found Valves at the origin of the Mesenteric and Haemorrhoidal Veins, and in those of the Spleen ; and in the Dog and Sheep, l}e met with them n the Pulmonary Veins. The Pulmonary Veins, like their corresponding Ar- teries, vary in the number of their principal Branches, corresponding with that of the Lobes of the Lungs. The most singular appearance among the Veins is found in the Foot of the Horse, where they form an intricate Plexus, which completely covers the surface of the Coffin Bone. In some Animals, as the Seal, there is a remark- able distribution of the Veins of the Kidney, which form a Net-work that is expanded over the surface of that Organ. In several of the Amphibious Quadrupeds, and in the PART L] OF MAMMALIA. the Cetacea, particular Vessels are found much enlarg- ed, especially the Posterior Cava at the Liver. This is most remarkable in the Seal, where it is dilated into a Sac or Reservoir, which receives and retains the Blood while the Animal is under water, till it can come to the surface and respire* OF 104 OF THE ABSORBENTS [PART I. OF THE ABSORBENTS, 1 HE Absorbent System of Mammalia consists, as in Man, of Lymphatics, Lacteals, Conglobate Glands, and Thoracic Duct. The structure is the same as in the Human Body. The Absorbents are provided with Valves, and have also two general terminations in the opposite sides of the Neck. They differ a little in the distribution of their Glands, and in the origin, course, and termination of their principal Trunk, the Thoracic Duct. The chief parts of the Absorbent System were first discovered in Quadrupeds, the subjects for examination being more readily come at here, and the contents of the Lacteals being of the same white colour as in the Human Body. The Lymphatics in Quadrupeds, as in Man, have been seen in the different parts of the Body, excepting the Brain and Spinal Marrow, in which their existence has not yet been ascertained. In the Posterior Extremities of the larger Animals, as the Horse, they are easily traced ; and in the Inter- nal Viscera, in some Animals, as the Ox, they can be seen i* V PART!.] OF MAMMALIA. 10& seen to greater advantage than in the Human Body. In the Sheep, Goat, &c. the Lacteals run in Trunks of considerable size, and are readily detected in the Car- nivora, as the Dog, by feeding the Animal with Milk, or other nourishing substances, and a few hours after- wards laying open the Abdomen. The Absorbent or Conglobate Glands are fewer in number, in this class of Animals, but larger, and more collected together, than in the Human Species. The Glands of the Mesentery, in many of the Mammalia, particularly in Carnivora, are united into a mass, term- ed Pancreas ASELII, in consequence of the Discoverer mistaking them for that Organ. In a few Animals, they form two groups, or in some, one group, and an accessory one. In Rwninants, they are dispersed over the Mesentery, corresponding seem- ingly with the great size and length of the Intestines in Herbivorous Animals. The connection between the Absorbents and their Glands is observed to be less general in Quadrupeds than in Man, there being few instances where Branches reach the Thoracic Duct in the Human Body, without previously entering one or more Glands ; whereas, in Quadrupeds, it appears that many Absorbents go di- rectly to the Common Trunk, without the intervention of Glands. The internal structure of the Absorbent Glands has been observed in some of the larger Animals of this class, and in a few, as Solipeds and Cetacea, they have had more of a Cellular than Vascular appearance ; but the 106 OF THE ABSORBENTS [PART!. the ultimate structure here, as in Man, is not yet suffi- ciently ascertained. The course and termination of the Thoracic Duct varies a little in different Animals. In some, as the Dog, it forms two distinct Canals ; in others, as the Sea-offer) three or four Trunks are found. It forms, more constantly than in Man, a Vesicular enlargement, or Receptaculum Chyli. It makes no circuitous turn previous to its termina- tion, the horizontal situation of Quadrupeds allowing a readier course to its contents. There are also fewer Valves here than in Animals moving in the upright position. In the Horse, only a single pair is observed ; while in the Ape, as in the Human Body, there are several Valves, to favour the passage of the Lymph and Chyle, or at least prevent their reflux. OF PART I.] OF MAMMALIA. 107 OF THE STOMACH. 1 HE shape, proportional size, and general appearance of the Stomach, vary considerably in different Mamma- lia. In most Carnivorous Quadrupeds, it bears a strik- ing resemblance to that in Man. In some, however, it is long ; in others, of a roundish form. In many, it is simple ; in several, it is divided into different apart- ments. It is termed complicated, when the Cavities within it have the same appearance ; and compound, when they are of a different nature, particularly within. The number of the Coats of the Stomach is the same as in Man, but the Muscular and inner Coat vary much in appearance. In Carnivora, the Muscular Coat is proportionally strong, to enable the Stomach to act more powerfully on its contents. The inner surface, as in the Human Species, appears to be destitute of Glands, though they are observed in a few about the Cardia and Pylorus. In the Carnivorous Quadrupeds, the Cardia and Py- lorus arc more directly on the extremities of the Sto- mach, than in the Herbivorous ; in consequence of which the Food has a readier passage into the Intestines. In 10* OF THE STOMACH [PART I, In Ruminants, these two openings are closer together, leaving a Cul-de-Sac on each side ; from which circum- stance the Food is longer detained. In the Ape tribe, particularly the Qurang-outang, the Stomach varies little in its general appearance from that in Man. There is but one Stomach in Animals destitute of Teeth, as the Ant-eat er, and also in the Ornithorryn- cJnis, which has a Horny Papilla near the Pylorus. In many of the Glires, the Stomach is uniform ex- ternally, but divided into pouches internally. In the Hat tribe, the greater number have two Pouches, some three, some only one. In the Hare aud Rabbit, it is also single, but has two apartments internally, formed by its inner Coats. The left portion is lined with a Cuticle, the right is Villous, and the Food is observed to be more digested in the latter. In the Opossum, the Stomach is peculiar in having its two openings close to- gether, resembling those of Birds. The Beaver has a Glandular Body at the Cardia, resembling the second Stomach of Birds. In the Porcupine are three Sto- machs of unequal size. Of the Fercu, the Kangaroo Rat has the Stomach di- vided into two large Guts - 9 and. in the Kangaroo Giant, it forms only one, which is so large as almost to fill the Abdomen, and is formed into Cells by longitudinal Muscular Bands. There are two remarkable Appen- dices at the Cardia. In Carnwora, the Stomach is larger in proportion than in Man, and is placed more in a longitudinal direc- tion. It is also thicker and stronger, in consequence of which PART!.] OF MAMMALIA. 109 which hard substances are more readily digested. In the Dog, the Rugae go length-ways between the Cardia and the Pylorus ; the Esophagus opens so freely into the Stomach, as to enable the Animal to vomit readily. In the Lion, Bear, Sec. the Stomach is divided by a slight contraction at its middle, into two portions. In the former, the Esophagus enters directly at the end of the Stomach. The Cat has a single Pyramidal Sto- mach. Among Amphibious Animals, as the Seal, some have a single Stomach, with the Esophagus entering directly at its extremity. In others, again, as the Tri checus, or Sea-cow, it is complicated, and is remarkable, according to CUVIER, for having a Gland as large as a person's head, in which a fluid, like that of the Pan- creas, flows into the Stomach by numerous pores. Some Herbivorous Animals, as the Horse, have the Stomach simple, and uniform in its appearance exter- nally j but the inner surface has the left portion covered with Cuticle, as in the Esophagus, and the right Vil- lous. The Muscular Coat has several Layers running in different directions. In Herbivorous Animals in general, the Esophagus terminates in such a manner in the Stomach, as to pre- vent the ready return of the Food ; and this is consi- dered as one of the causes of these creatures not having the power of vomiting like the Carnivora, excepting in extraordinary cases ; in Ruminants, however, that do not vomit, the passage into the Stomach is free. The inner part of the Stomach, in some other Animals, as the Hare, Rabbit, and several of the Mmise or Rat kind, has the left portion Cuticular, while 110 OF THE STOMACH [PART!, while the right has the Villous appearance. In this, also, the Food is found to be more fully digested ; from which circumstance, this kind of Stomach forms a medium between that of Ruminants, and the Stomach of Animals, that is entirely Villous on the inner side. All Pecora have a plurality of Stomachs, some two, others three, and some four. In all of them, the Stomach is compound, and more complicated, both in structure and appearance, than in any other order of Mammalia. They are the only Quadrupeds which ru- minate their Food. Taking the Ox for a general ex- ample of the structure of this Organ, thejrs Stomach is the Ventriculus, or Paunch, which occupies a great part of the Abdomen, especially in the left side. It is by much the largest of the four. It has two Sacs or Appendices externally, and is slightly divided into four apartments internally. The inner surface is covered with innumerable Papillae, of different size in different parts. The second Stomach is termed Reticulum, Bonnet, or Honey-comb Bag, and appears as a Globular Appen- dage of the Paunch. It is placed at the right side of the Esophagus, and anterior part of the first, and ha generally a thicker Muscular Coat than the former. Its inner surface is arranged into regular Pentagonal Cells, and covered with fine Papillae. The third is the smallest, and called Omasum, or Many Plies. It is situated on the right side of the Paunch, is of a Globular form, and has a thinner Mus- cular Coat than the two former. It consists of nume- rous broad Laminae sent off from the Internal Coat> running in a longitudinal direction, alternately varying in PART!.] OF MAMMALIA. Ill in breadth, and covered with small Granulous Pa- pillee. The fourth Stomach, the Obomasum, Ventriculus In- testinalisy Caille or Red, has a Pyriform appearance, and is next in size to the Paunch. It has large longitu- dinal Rugae, covered with Villi, in which circumstance it is somewhat like the Stomach of the Dog. The Muscular Coat is still thinner than that of the former. The fourth Stomach, in the Foetus, with the Milk cur- dled in it, forms the Runnet ; but it is observed, that in all Animals, there is only one digestive Stomach, and this has also the power of curdling Milk. The in- ner surface of the three first Stomachs is covered only with a fine Cuticle, while that of the fourth has the ap- pearance of being a real Mucous or secreting Mem- brane. Upon examining the openings of the Stomachs, the Esophagus is observed to open into the right of the Paunch, and at the same place by a Gutter, into the second and third Stomachs. The third leads in, by a narrow opening, to the fourth ; and this terminates in the Duodenum, which has a Pylorus at its origin. In the different individuals of this order, the Sto- mach varies in proportion as the Animal advances to- wards maturity. While it is young, and fed upon Milk, its fourth Stomach is the largest. The Milk passes at once into this Cavity, very little going into the other three. As soon as the Creature begins to eat solid Food, it acquires the power of ruminating. It lays hold of the grass, &c. by pressing it with the Tongue against the roof of the Mouth, and, by the Gums 112 OF THE STOMACH [PART I. of the Upper, and Teeth of the Under Jaw, assisted by a twist of the Head, tears it across. After a slight mas- tication, the Aliment passes into the Paunch, and from that, by small portions, into the second Stomach. When a considerable quantity has been swallowed, a morsel is thrown back with velocity from the Stomach into the Mouth, where it is accurately ruminated, and then carried directly to the third Stomach, the groove being contracted between this and the two first. This Process is continued till the whole of the Food has un- dergone the same operation. In the third and fourth Stomachs, a more complete digestion takes place. The Stomachs of other Horned Ruminants differ little in their nature from that of the Ox. In the Deer, the Paunch has three Pouches appearing externally, and the Papillae are less conspicuous than in the Ox. In the Dromedary, Camel, and Lama, there are four Stomachs, as in Horned Ruminants, but the structure is different. In the Camel and Lama, there are nume- rous Cells in the substance of the first and second Sto- machs, formed by strong Muscular Bands crossing each other at right angles. By the action of these, it is sup- posed the Animals can open or contract at pleasure the mouths of the Cells, which serve as Reservoirs of the drink, so as to expel the contained fluids, or retain them even for several days. The water they take in is observed to be rendered turbid in the first Stomach, by the mixture with the Food, but becomes pure in the second. After rumination, the Animal can draw the third Stomach to the Esophagus, and receive the rumi- nated Food, without polluting the water in the Cells. Of PART L] OF MAMMALIA. lot OF THE LARYNX, THE Larynx agrees, in its general structure, with that in Man. It differs chiefly according to the form of the Cartilages, the size and form of the Ventricles, and of certain Sacs connected with these, in particular Animals. Most of the class have a Muscle peculiar to the Epi- glottis, and termed Hyo-Epiglottideus. It is; commonly cylindrical ; arises by two portions from the Base of the Anterior Cornuaof the Os Hyoides, and is inserted into the middle of the Epiglottis, which it serves to raise from the Glottis. The Epiglottis exists in Mammalia in general, with very few exceptions. It is so small in the Bat tribe, as to be scarcely observable. It appears to be deficient, or very small, also, in some of the Mouse-like Animals, as the Gits EsculentuS) or Rel- Mouse. In the Ape tribe the Larynx differs little from that in Man, excepting that the Ventricles are a little larger. In the Ourang-outang the Ventricles of the Larynx are very large, and each divided into two by a semi* partition ; above which is a Foramen, leading to a large Sac, discovered by PR CAMPER. The?e Sacs are unit- VOL, IV* G * d 108 OF THE LARYNX, &c. [PART I. ed together by Cellular Substance, but do not commu- nicate with each other, except through the medium of the Larynx. Many of the other Apes and Baboons, though not the whole, have also in their Throats large single or double Sacs of different forms, communicating with the La- rynx by one or two Foramina, between the Os Hyoides and Thyroid Cartilage. These Sacs vary in size in dif- ferent individuals, and become larger as the Animal ad- vances in years. During respiration, part of the air enters these, which in time of crying are dilated, but can afterwards collapse by the pressure of the surround- ing Muscles. It is supposed by some, that the voice of these Animals is rendered proportionally weak, from part of the air getting into the Sacs. In the American Monkeys, the Arytenoid Cartilages are diminutive, and turned back. The Cuneiform Car- tilages, and Cellular Substance, on each side, form anteriorly a cushion, which touches its fellow; and, with the other parts of the Larynx, they compose a strait passage, turned like an /, which gives the flute-like voice in the Whistling Monkeys. The Hoveling Apes have the anterior part of the Os Hyoides formed into a spherical cavity, by which the tones are produced which are heard at a great distance. The principal differences in the Larynx, among the other orders of this class, are the following : In the Ant-eater, which is observed to be dumb, BLU- MENBACH found the Larynx entirely Osseous. In the Qrnithorrynchus, each of the Ventricles has only one Ligament of the Glottis. Among PART L] . OF MAMMALIA. 109 Among the Glires, some, as the Procupine, have scarcely any vocal organs ; others, as the Rat y have them more distinct. In the Fer it is the greatest, though some Authors have supposed the Biliary Ducts terminated nearest the Pylorus in vo- racious Animals. In the Ornithorrynchus, two Branches of the Hepatic Duct unite with the Cystic near the Neck of the Gall-blad- der. In some of the Bat kind, in Rats, and in the Porcu- liinesmd Hedge-fiog, many Hepatic Ducts join the Cystic near each other, or in succession. The Mole has two Hepatic Ducts, one of which receives the Cystic, then unites with the other to form the Common Duct. In the Seal, one Branch of the Hepatic Duct joins the Cystic near the Neck of the Gall-bladder ; the second unites with the Cystic near the insertion in the Intes- tine, and the Cystic Duct appears to form the common one. The Martin kind have the common Duct dilated into PART I.] OF MAMMALIA. 13$ a second reservoir. In some Animals, as the Horse, which are destitute of a Gall-bladder, the dilatation of the Hepatic Duct, at its origin, is so large as to form a sort of reservoir for the Bile. In the Equus Q}tagga % however, an Animal lately introduced into this country from the Cape, though the Gall-bladder is wanting, there is no dilatation in the Hepatic Duct. The Ductus Com- munis, in the Cat tribe, after perforating the Muscular Coat of the Intestine, forms an Ampulla with two a- partments, previous to its termination. In the Pig, the Ductus Communis is of great size, and terminates very near the Pylorus. In the Elephant^ nine or ten Biliary Ducts unite into a Trunk, which forms an oval Sac in the substance of the Duodenum. This divides into Cells, one of which terminates in the Intestine by a small orifice. In the Dolphin and Porpoise, the Hepa- tic Duct terminates in the last of the Stomachs. Besides the Biliary Canals mentioned above, there are, in some Animals, as the Hare, Dog, Ox, and Sheep * others, termed Hepato-cystic, which terminate in the Body or Neck of the Gall-bladder, and thus convey the Bile directly into it from the Liver. PANCREAS. The form, proportional size, and colour of the Pan- creas, vary a little in different Quadrupeds ; but the structure of this Conglomerate Gland is the same as in Man. In most Mammalia, it is separated into Branch- es, which extend in different directions, its principal .part being always placed transversely behind the Sto- and between the Spleen and Duodenum. In 136 OF THE PANCREAS [PART L In the Ourang-outang, it is of the same figure as in Man. In the other Quadrupeds, it is less or more di- vided. There is commonly but one Pancreatic Duct ; seldom does any Branch go off from it to terminate se- parately in the Duodenum. For the most part, the Pancreatic and Biliary Ducts have a common opening. Of the Apes, some have the Ducts united ; in others, they terminate at a distance, as also in the Hare, Porcupine, and Hog. In the Dog 9 one Pancreatic Duct goes into the Ductus Communis, and another into the Intestine. In the Cat, it termi- nates in one of the Cells of the Ampulla in the Ductus Communis. In most of the other Carnivora, the Pan- creatic and Biliary Ducts are generally united. In the Horse, they terminate separately, though near each other. In Ruminants, they commonly unite at their termination. In the Pig, the Pancreatic Duct ends at a great distance from the Ductus Communis. In the Elephant, as in the Cat, it opens into one of the Cells of the Ampulla in the Ductus Communis. SPLEEN. The Spleen is found not only in all Mammalia, but in most Vertebral Animals, and is observed to diminish in the proportional size from Quadrupeds down to Fishes. There is only one Spleen in Quadrupeds, but in the Dolphin and Porpoise, there are several of unequal magnitude, but so small, that if taken collectively, they would PART!.] OF MAMMALIA. 137 would not equal the size of the Spleen in the Quadru- peds. The colour is commonly of a deeper red than in Man, but varies a little among the different individuals. The form also varies considerably. In many of the Ape tribe, it is triangular; in the OrnithorrynchuS) quadrangular, and larger than the Stomach ; among the Glircs, triangular, as in the Water Rat and Indian Hog, or long and narrow, as in the Rabbit ; in the Carnivora, generally long, prism atical, and flat ; in the Horsey flat and triangular; in Ruminants, generally large and long, in some of these, in form of a crescent ; in others, as the Deer, flat and roundish ; in the Hog and Elephant, it is very long. The attachments of the Spleen are as in the Human Body, but it is often placed across the Abdomen. In Ruminants, it is fixed to the left side of the Paunch. The structure in the greater part of the Animals of this class, is somewhat similar to that in Man ; but in the Ox and Sheep, it is peculiar for the appearance of its Cells. OMENTUM, The Omentum exists in all the Mammalia, and is pe- culiar to this class, though something similar to it is observed in several other Animals. It varies less in its extent and general appearance in the same Species, than in Man. It commonly goes as far in one direc- tion as the Kidneys, and in another, extends to the Pubes. In the Ourang-outang, the Omentum is as in Man ; VOL. IV, I bat 138 OF THE OMENTUM [PART L but in the rest of the Ape tribe, it is similar to what is found in other Brutes. In Carnivora and Ruminanls y its extent is very great. In a few Animals, on the con- trary, as the Brown Bear, it does not reach the middle of the Abdomen. The Omentum, in this class of Animals, frequently contains much Fat, and the spaces between the diffe- rent Striae of Fat are composed of the same kind of fine Membrane as in the Human Body ; but the quan- tity of Fat depends greatly on age and habit of life. In Herbivorous Animals, it is generally furnished with more than in the Carnivorous ; but in both, the quan- tity depends much upon rest. It is also affected by the season, moderate heat increasing the quantity ; though-, on the contrary, in Animals that remain benumbed in winter, the Omentum is charged with this substance. Many of these, as the Dormouse, the Marmot of the Alps, &c. have, in addition to the Omentum, two fatty Appendices, which cover the Intestines in the lateral parts of the Abdomen ; and these Animals have also a large quantity of Subcutaneous Fat, which may also serve as a reservoir of nourishment ; but these fatty ap- pendages are absent in some of the Dormice, the Bear, &c. though of the same nature with those that have them. KIDNEYS. . The structure of the Kidneys, in Quadrupeds, is analogous to that in Man ; but they vary, in different Animals, in situation, form, relative thickness of their two FART L] OF MAMMALIA. 139 two substances, in the number of their Papillae and their corresponding Infundibula, and in the absence of these. The situation differs from that in the Human Body* in the right being commonly higher, or, strictly speak- ing, farther forward than the left. The form is most frequently like that in the Human Body, but sometimes Globular, as in the Dog ; triangular, as in the Horse / and long, as in the Hog ; but the greatest difference is in their division into Lobes. In many of the Glires, and in the different Feree, they are simple, each having a Cortical and a Medullary part, with only one Papilla. In many individuals of the class, they form what are termed Conglomerated Kidneys, being divided, not only in the Foetus, as in the Human Subject, but during Jife, into a collection of smaller Kidneys. In the Ox and Elephant, the Kidneys are separated into Lobes, of which there are in the former between twenty and thirty, and in the latter four ; but they are deeply di- vided in the Bear, Otter and other Amphibia, and in the Cetacea, so much so, as to appear like a bunch of grapes, and are connected only by their Sanguiferous and Urinary Vessels. These Lobes are for the most part numerous, being in the Bear fifty or sixty, and in some of the Cetacea^ the number is still greater j but the cause of this division is not ascertained. It has been supposed that they are peculiar to Animals which live in or frequent the Water ; but the Branson or Land Bear has the Lobular Kidney, as well as the Polar one, which inhabits the coasts and water. The limits of the two substances are commonly dis- I 2 tinct, 140 OF THE KIDNEYS [PART!. tinct, but they have not always the same proportional thickness, in some, the Cortical being three or four times thicker than the Medullary part. The Medullary Substance does not constantly terminate in Papillae. In the Dog, Cat, some of the Opossums, &c. the part which transmits the Urine forms a Cavity, the surface of which, however, is pale, like that of the Papillae. In many Animals, as the Squirrel, Hare, &c. there is but one Papilla ; in some of the Rat kind, two ; in the deeply-divided Kidneys, commonly but one in the Lobe ; but in the Bear, each Lobe is found to have two PapiJlse. The number of Infundibula corresponds with that of the Papillae ; when these are absent, the Pelvis is joined to the edges of the surface which sends out the Urine, and then, as happens in the Cat, it does not appear beyond the Kidney. In the Bear, and other Animals with Conglomerated Kidneys, the Infundibula unite in succession, and go to the Ureter without forming a Pelvis. The Ureters agree, in Mammalia in general, in their course, size, proportional length, structure, and termination. In the Lobulated Kidneys, the Arteries do not all go into the Sinus of the Kidney, many of them taking a more direct course towards the Lobes to which they are destined. RENAL GLANDS. The Renal Gland is generally situated at the inner part PART 1.] OF MAMMALIA. 141 part of the Kidney, and varies in proportional size al- DK)st in every Species j but it, appears to change with age much less than in Man. Its use here, as in the Human Body, has not been discovered, though it is considered as subservient to the Kidney. Among the Glires, It is proportionally large, being from a 12th to a 4th part of the bulk of the Kidney ; while, in the Fer& 9 it is in general not more than a 20th or a 50th part. The form, also, of this substance is very various. In Solipeds and Ruminants, it is often round, or cylindri- cal, or conical. In many Animals, its external appear- ance is very similar to that of the Kidney. In the Ce- tacea, it is divided into numerous Lobules, which have generally two distinct substances, the outer yellowish, the inner a deep brown, and softer than the outer. The external is often more than half the thickness of the Gland ; but the colour and distinction of substance vary much in different Animals. In some, as the Ele- phant 9 this is scarcely observed ; in others, as in some of the Gliresy three or more substances of different co- lours have been found. BLADDER. All Mammalia have a Bladder of Urine, but it is more loose than in Man, and is completely covered by the Peritoneum. The shape is also different ; the bot- tom, or Fundus, on account of the horizontal situa- tion of the Animal, being most dependent, becomes the widest part. In Herbivorous Animals, particularly I 3 in 142 OF THE BLADDER [PART L In the Pecora, the Bladder is much larger, and more dilatable, but less thick and strong, than in the Carni- vora ; hence the latter are observed to evacuate the Urine more frequently. The structure of the Bladder varies in these two kinds of Animals. In Carnivora, it is commonly com- posed of strong Fasciculi of Muscular Fibres, some transverse, others longitudinal. Some Herbivorous A- nimals, as the Horse, have also a thick Muscular Blad- der ; while other Herbivora, and some Omnivorous A- nimals, as the Ape tribe and Hog, have the Bladder proportionally not thicker than in Man. OF PART!.] OF MAMMALIA. H3 OF THE MALE ORGANS OF GENE- RATION. i STS. The Testes are found in all Male Animals, except in those of the very lowest orders. In the different Mammalia, as in Man, they are two in number ; but there is considerable variety in their situation and struc- ture. In the Ape tribe, in most of the Carnivora, in Soli- peds, and in most Ruminants, they are placed in a Scrotum, with a Cellular Partition. They are pendu- lous in such Animals as have Vesicuke Seminales, where the Semen is readily conducted to the Penis. In the Kangaroo and Opossum, they are placed at the fore part of the Pelvis, in a Scrotum without any partition. In the Bellutz and Civet, they are situated under the Skin of the Perinqeum. In the Otter and Camel, they lie under the Integuments of the Groin. In the Bat, Squirrel, Rat, Guinea Pig, Beaver, Por- cupine, Hedge-hog, Shrew, Mole, &c. they pass from the Abdomen into the Scrotum upon certain occasions, particularly at their seasons of sexual intercourse. In the Oniithorrynchus, Elephant, Amphibious Mam- malia, and Cctacea, they remain constantly in the Ab- I 4 domen ? 1U URINARY AND MALE ORGANS [PART I. domen, in the vicinity of the Kidneys ; and here, as in other cases where they are situated in the Abdomen, they are covered by the Peritoneum, but want the Cre- master Muscle, which exists wherever the Testicle passes out of the Abdomen. Besides the Scrotum, the Testicle, as in Man, has its Tunica Vaginalis, and, unless in Man and the Ou- rang-outang, there is constantly a small passage leading between this Coat and the Abdomen, in such Animals as have the Testes always in the Scrotum, but a large communication in those where these Glands pass from and to the Abdominal Cavity. In neither of these cases is the Animal in danger of Hernia, this being the highest part of the Belly, or at least, the \ 7 iscera press less upon the Abdominal Rings. The Testes are cover- ed also in Mammalia by the Tunica Albuginea, which differs only in thickness. The form of the Testes is generally oval, sometimes round, as in the Rat, or very ]ong, as in Amphibious Mammalia and Cetacea. The size, in many, increases greatly at rutting-time. The Seminal Tubes, in some Animals, are collected into Bundles, as in the Baboons, most of the large Carnivora, the Boar, &c. ; but in most of the Glircs 9 and especially the Rats, the Tubes are large and paral- lel, and so loosely connected 'as to be easily separated from each other. In several Quadrupeds, as the Dog 9 Horse , Ham, &c. there is a Body termed Corpus Highmorianum, running lengthways next the Epididymis, and composed of condensed Cellular Substance, which sends Septulie be- tween PART!.] OF MAMMALIA. US tween the different bundles of the Seminal Tubes of the Testicle, to protect and bind these together. The form and relative size of the Epididymis varies much in different Animals. In most Mammalia, it is fixed to the Testicle as in Man ; but in many of the Glires, as the Rat, and in Animals with a Pouch, it is only connected to the Testicle by two thin Cords. The Vasa Deferentia, as in Man, are thick and firm, but thinner where the Testes lie constantly in the Ab- domen. As in the Human Species, also, the Vasa Deferentia, in many Animals, are enlarged in size, and are Cellular internally, for some space previous to their termination. The Cells, in the Horse, and also In the Ram, have small orifices internally, from which a thick white fluid can be pressed into them. In the Elephant, the dilatation is of a Globular form. Most Mammalia possess Vesicula Seminales, which, in many, as in some Apes, but particularly in the Hedge-hog, are greatly enlarged, like the Testicle, when these Animals are in season. The Vesiculae exist in Apes, in Bats, in the Glires, in the Hedge-hog and Ra- coon, in Solipeds, and in the Bellua. They are wanting in the OrnithorvyncJius, in Carni- vora, in Ruminants, unless two small Glandular Cap- sules, considered by some as Prostate Glands, be taken for such, and in the Cetacea. There is no rule yet known with respect to the presence or the absence of these. Their form and structure vary exceedingly in diffe- rent Mammalia. They are commonly Membranous Cellular, but in many cases they have a Glandular appearance 146 URINARY AND MALE ORGANS appearance internally. When very large, as in the E- lephant, they have a peculiar Muscle which covers them. In many Animals, each Vas Deferens unites with the Vesicula of its side -, in others, the Vasa De- ferentia and Ducts from the Vesicular terminate by a common opening in the Verumontanum. In the Ape tribe, the appearance of the Vesiculae Se- minales is nearly the same as in the Human Body. In most of the Glires, they are remarkable for their great size. The Vcsiculae of the Squirrel are par- ticular in being placed upon the inner side of the Vasa Deferentia. In the Rat, they are so large as to be partly without the Pelvis. The Guinea Pig has them of a long cylindrical form, and containing a cheesy-like substance. In the Hare, their place is sup- plied by a rectangular Sac, which has in one part a Glandular appearance, and opens into the Verumonta- imm along with the Vas Deferens. In the Hedge-hog, they exceed the size of the Testes, forming on each side four or five Fasciculi, each of which is composed of a Tube wonderfully convoluted. The different Tubes join into one Canal, that opens into the Veru- montanum along with the Vas Deferens. In the Horse, Boar, Elephant, and Rhinoceros, the Vesiculse are of great size,, and form on each side a common Duct with the Vas Deferens. Fesiculae Accessories. These are Membranous Tubes, varving in number, and situated at the inner side of the Vesictike Seminales, or at the origin of the Ure- tjbra. They terminate by one or more Excretory Ducts .m common with the Vesiculse Seminales and Vasa De- ferentia, PART!.] OF MAMMALIA. H*7 ferentia, or separately. They are like the Vesiculae Se- minales in structure, and increase like them at rutting- time. They are observed to be filled also apparently with the same kind of liquor. They exist in most of the Glires, as the Rat, and in the Hedge-hog and Mole among the Carnivora, but ap- pear to be wanting in the other Mammalia, the Horse excepted, in which there is a cylindrical Vesicle placed between the Vasa Deferentia, and terminating in the Urethra, before the openings of the Vesiculae Semina- les and Vasa Deferentia. Prostate Gland. The Prostate Gland, or something analogous to it, appears to exist in all the Mammalia, but varies exceedingly in its appearance in the different Species. In some, as the Dog and Cat tribe, it is single ; in others, as the Ruminants, it is double. In a small number, as the Horse and Elephant, it is qua- druple ; and in the Bat, it is Jobulated. In most of the Animals of the class, the structure is as in Man. In others, as the Horse, lluminants, and the Elephant, it has Cavities within. In the Cetacea, it is Cellular, and of great proportional size. It gene- rally surrounds the beginning of the Urethra, and ter- minates in that Canal by one or more openings at the side of the Verumontanum, though sometimes consi- derably farther forwards. In the Horse and Elephant, the Prostates are covered by Muscular Fibres, which proceed from the sides of the Bladder. In most of the Glires, and in the Hedge-hog and * Mole., 148 URINARY AND MALE ORGANS [PART I. Mole, the place of the Prostate is supplied by the Ve- fciculae Accessorial. Cowper's Glands. They exist in most Mammalia, but are wanting in many, as the Hedge-hog, Mole, Dog, some of the Bear tribe, Otter, Sollpeds, many Rumi- nants as the Deer, in the Seal, and the Cetacea* They arc frequently found with the Prostate and Ve- siculae Seminales, or with the Vesicular Seminales and Vesiculye Accessories, or with the Prostate alone. Their structure varies considerably among the diffe- rent Animals; sometimes they have a dense or close texture, as in the Ape tribe, Carnivora, and Ruminants , at other times, they have a Vesicular appearance, as in the Squirrel, Marmot, &c. They are constantly filled with a peculiar liquor, of a bluish-white colour, of the consistence of thick mucilage, which passes into the Urethra by a single Duct, In Apes, they are proportionally much larger than in Man. In the Cat kind, they are also remarkable for their size. In general, they have a Muscular Sheath which incloses them, and may enable them to expel the fluid they contain. The number of these Glands is remarkable in Mar- supial Animals, four being found in some, and six in others. PENIS. The Penis, in Mammalia, is constantly single and pervious, and varies in size, form, and situation. In the Ape tribe and Bats, it is suspended from the Pubes, as PART!.] OF MAMMALIA. H9 as in the Human Body. In the greater number of Quadrupeds, it passes towards the Umbilicus, where there is an orifice for its exit, and in its course is in- closed in a sheath of the Integuments, lined in some by a Cellular, and in others by a LJgamentous Substance. When relaxed in the sheath, it turns more or less in a waving direction, on account of its length. In most Ani- mals, it is situated under the Abdomen, having on each side a Muscle, which arises from those at the middle of the Abdomen, and is fixed to the Prepuce, and another, arising from the Vertebrae of the Tail, or Muscles about the Anus, and inserted along the Penis, as in Carni- vorct) or in the sheath that covers it, as in Ruminants. The first is the Adductor, and the other the Retractor, of the Prepuce. In some Animals, as the Squirrel, Dormouse, Rat, Marmot, Guinea Pig, Hare, Opossum, Lion, and Ca- mel, the Penis goes to the anterior part of the Pubes ; or in some, it passes directly out of the Pelvis, then proceeds to the side of the Anus. Animals of this last kind are termed Retromingents, the Urine being voided backwards in both sexes, and they are, contrary to an ancient opinioH, found to copulate forwards, like other Quadrupeds. In the Cetacea, the Penis is long, slender, in the form of an f, and is situated within the Abdomen. When they copulate, the Female turns upon her back, and the Male slides on. The length of the Penis varies according to its situa- tion. In the Lion and Cat kind, it is so short, that the Male uses his Teeth and Claws, to enable him to cling better 150 URINARY AND MALE ORGANS better to the Female during copulation. The form is as variable as the length in this class. It is somewhat cylindrical in the Ape kind and Glires, slender in the Boar and Ruminants, cylindrical in the Horse and Ele- phant, large and conieal in the Porpoise, and large, co- nical, and flat in the Dolphin. The Crura Penis, in Mammalia, are proportionally short. They adhere to the Bones as intimately as in Man. In the Dog and some Apes, there are two Corpora Cavernosa, with a Septum Penis ; in others of this last tribe, the Septum is wanting or incomplete. It is ab- sent in Solipeds, Ruminants, and Cetacea, and in most Bellua ; in which case, there is only a single Corpus Ca- verriosum. In the Elephant, there is a complete Septum* The Omithorrynchus and Kangaroo are remarkable for having four Crura Penis, and the Urethra in the axis of the Corpora Cavernosa, which form a cylindrical ring, with a Septum both above and below it. In several Mammalia, there is a Bone in the Penis, for conducting it into the Vagina. This is found more frequently in such Animals as have no Vesiculae Semi- nales ; in these the copulation being tedious, they turn averse from each other during the emission of the Se* men. But it is found also in some where these Bodies are present. It exists in most of the Ape tribe, though here it is small ; in Bats, and several Rats ; in the Badger, Bear, Weasel, Dog and Cat kind -, in the Seal, and in the Balena among the Cetacea. It is wanting in the Opossum, Hyena, Solipeds, Ruminants, and Bel- luce. When present, it makes part of the walls of the Penis, PART!.] OF MAMMALIA. 151 Penis, the Corpora Cavernosa being then less exten- sive. It is commonly cylindrical, though sometimes furrowed, making part of tho Urethra. In the Bear, Dog, &c. it forms a large part of the Penis. In most of the Gliresj and in the Cat, it is proportionally small. The Urethra, as in Man, is continued from the inner lining of the Bladder. In the Horse, it has been ob- served to have externally transverse Muscular Fibres from one extremity to the other. It is divided into a Posterior and an Anterior Portion ; the former, at the sides of the Verumontanum, receives the Semen and liquor of the Prostate Gland. The posterior portion of the Urethra varies in length in different Genera. In some Apes, it is short, as in Man. In some other Animals, as the Civet Cat, Kan- garoo Rat, it is about half the length of the Canal. This portion is termed by some Muscular, as being inclosed in a layer of Muscular Fibres running more or less in a transverse direction ; and in some, as Solipeds and Ruminants, it is of considerable thickness and strength, thereby assisting in the expulsion of the Se- men. The other portion of the Urethra begins by a Bulb, and is commonly placed under the Corpora Cavernosa, and inclosed by walls of the same nature with those of these Spongy Bodies. It begins behind by two Crura, each inclosed in a separate Muscle. The Bulb of the Uretbra is thin in Carnivora,but of considerable strength in Solipeds, Ruminants, and Bellutz. The Glans Penis varies in form and structure almost in 152 URINARY AND MALE ORGANS [PART I. in every Genus. In some, as the Ape tribe and Horse, it is dilated somewhat, as in the Human Species. In others, as the Boar, and many Ruminants, it is conical and pointed, and in some turned to one side. Many others, as the Carnivora, Lave it also conical, but with the addition of the Os Penis, which commonly projects to the extremity of the Glans. In the Elephant, if; is cylindrical like the Penis, and then contracts at the ex- tremity. In many, the Glans has a Tendinous appearance. In some, it is covered with hairs ; in others, with scales -, and some of the Cat tribe have retroverted Spinous Processes, which may assist in enabling the Male to cling to the Female till the Semen is evacuated. In the Badger, Dog, &c. or such as have the copula- tion tedious, there is a double Glans, or two Cavernous Prominences, one in the Body of the Penis, the other near its extremity. Behind the Prominences are two Veins, which are compressed by Muscles in the time of coition ; in consequence of which the return of the Blood is prevented, and the double Glans kept in a state of distension. Something of a similar nature is produced at this time in the Female ; the Vagina and its Corpus Cavernosum are contracted, by which the Animals are held together, and often contrary to their inclination, till the Semen is evacuated, and the parts relaxed. In the Opossums, the Glans is divided into two parts, each of which is perforated for the transmission of the Semen. At the division of the Glans, is the passage for the Urine. In the Echidna and the Ornithorrynchus Paradoxusj the PART L] OF MAMMALIA. 15S the Urethra, destitute of Cavernous Substance, is in- closed along with the Rectum, by a Constrictor Muscle, which terminates in the Cloaca, that receives the Se- men and Urine. The Penis is of considerable size, and, in the relaxed state, is situated in a Pouch. It terminates by two pervious Papillae, which conduct the Semen. The Ornithorrynchus Hystrix has a similar structure, but has a quadrangular Glans. Muscles, Sfc. of the Penis. The Erector Penis, and Accelerator Urinae, exist in all Mammalia, but vary according to circumstances. Besides these, certain A- nimals, as some of the Apes, the Dog, Hare, Rumi- nants, the Elephant, &c. have others, for supporting and giving proper direction to the Penis. Of the Blood-vessels, the Arteries are much after the same nature as in Man. The Veins form an intricate Plexus on the Dorsum Penis, from which Branches go to the Veins of the Groin. The Nerves are compara- tively very large, and embrace the Veins as well as the Arteries. VOL. IV. K OF 154- OF THE FEMALE ORGANS [PART- I. OF THE FEMALE ORGANS OF GE- NERATION. 1 HE Female Parts in Mammalia may, as in the Hu- man Body, be divided into Internal and External, which vary much among the different individuals of the class. The Uterus is situated horizontally like the Body. It advances in the Loins to the back part of the Kidneys ; is thinner, looser, and more tender, than in the Hu- man Species; and has internally a Glandular Mem- brane, but wants the transverse Rugae which are found in Women. In general, it resembles an Intestine, and has a real Muscular Coat. Of the variations of the Uterus, there is, 1. A Simple Uterus without Horns, and this generally pyramidal or oval, as in the Ape tribe, among the Qua- drumana, and in the Toothless Animals and Sloth^ in the order Bradypoda. 2. A Simple Uterus with Horns, or Uterus Bicornis. This, in some, is straight, in others convoluted, as in the greater part of the Glires and Carnivora, Solipeds, Ruminants, Belluce^ and Cetacea. 3. A Double Uterus^ or Uterus Duplex, having the appearance PART!.] OF MAMMALIA. 155 appearance of two Horns which open separately into the Vagina, as in the Hare and Rabbit. 4. A ])ouble Uterus with extraordinary lateral convo- lutions, or Uterus Aiifractuosus, as in the Opossum and Ka-nguroo. The Uterus of these Animals has several lon- gitudinal folds, one of which runs through its whole length, and divides it into two equal parts. The Cornua Uteri, contracted at first, soon dilate into large Cavities, each of which sends out a narrow Fallopian Tube, which is fixed to the extremity of the Ovarium. From the cor- ners of the Uterus, on each side, a Canal arises, which* after making a circuitous turn, approaches its fellow, and terminates in the Vagina by a narrow orifice at each side of the Meatus Urinarius. The Ovaria are as constant in the Female, as the Testes are in the Male. They are frequently situated near the Kidneys, are of an oval form, and have the Ova buried in their substance. In the Pigj they are tuberculated ; in the Hedge-hpg, they are in the form of a cluster of grapes. The num- ber of the Ova corresponds with that of the young which the Female is capable of producing during her life. The structure of the Uterine Tubes is generally the same as in the Human Species. In Uteri with Cornua, they are fixed to the latter, and are convoluted 5 but their diameter is always smaller than that of the Gornua. The Vagina is a continuation of the Uterus, and lies in the same axis with that Organ. It is in proportion to the size of the Penis in the Male, and to that of the Foetus, which has to pass through it. It has generally ilugae running longitudinally, to favour its dilatation. K2 I n 156 OF THE FEMALE ORGANS [PART I. In a few, as the Hyena, Dolphin, and Porpoise, the Kugae run transversely, but exist only at the outer half of the Canal. In large Animals, the walls of the Va- gina, according to CUVIER, possess Muscular Fibres, which run both in a longitudinal and in a transverse di- rection. In the Omithorrynchus, there is no Vagina. Vulva. This, in some Animals, as the Rat, forms a longitudinal slit ; in others, as the Hyena, it passes transversely. In some of the Glires, it is of a circular form, and sometimes, especially in Animals with a Pouch, it is inclosed with the Anus in a circle. The existence of a Hymen in Quadrupeds, resem- bling in form and situation that of the Human Subject,, is asserted by some late Authors of the first eminence^ and denied by others of equal celebrity. In the Dog, Cat, Ruminants, &c. the Vagina is se- parated from the Vulva by a contracted circle, and in other Animals, by one or more Plicae, which are found to be effaced by coition, or by one or more litters. In the Bear, Hyena, Mare, and Ass, never yet covered, a strong Semilunar Fold appears in the under part of the orifice of the Vagina, which has been considered by some as analogous to a Hymen, though there is no very strict resemblance to that in the Human Female. At the under end of the Vulva, the Urethra is com- monly situated, and appears at the outer orifice of the Vagina, though, in many Animals, the orifice of the Urethra is a considerable way in from the Vulva. The Nymphtf are wanting in Mammalia ; but the want of them is supplied, in coition, by the quantity of Blood which distends the Vessels at this time. In place of L] OF MAMMALIA. 157 of Labia Pudendi, there is generally a tliin border of the Integuments. A Clitoris is found in Quadrupeds in general, but placed in the lower part of the Vulva, corresponding with their horizontal situation. In the Ape tribe, it is larger than in Women, and is also of considerable size in most of the Glires, and in the Carnivom. The Pre- puce covering it forms, in some, as the Bear, a Pouch ; in others, as the Bitch, a Cul-de-Sac. In Animals where the Male has an Os Penis, the Fe- male has a small Bone in the Clitoris, as in the Glires, the Bear, Cat, Lioness, &c. ; but it is not found in the Dog kind. In the Eat tribe, the Clitoris and orifice of the Ure- thra are placed in front of the Vagina, appearing like the parts of an Hermaphrodite. In the Opossum, the Clitoris has a Bifid Glans, cor- responding with that in the Penis of the Male. In the Lemur Tardigradus, belonging to the order Quadruma- na, the Urethra runs through the Clitoris, and termi- nates upon its extremity. GRAVID UTERUS. The changes the Uterus undergoes by Impregnation, vary according to the nature of the Animal to which it belongs. The Os Tinea, in all the different Mam- malia, is closed soon after Impregnation, by a Gluti- nous Mucilaginous Matter, secreted by Glands or Fol- licles, which cuts off all communication between the K 3 internal 158 OF THE FEMALE ORGANS [PART!. internal and external parts, and prevents the lips of the Womb from growing together. The Corpora Lutea are found after Impregnation, and, in the Cow in particular, are large and of a yellow colour ; but in other Animals, the colour varies accord- ing to the kind. The Muscular Fibres in the Gravid Uterus become less distinct than in the unimpregnated state. The changes of the simple Uterus without Horns, or that belonging to the Ape tribe, &c. considerably resemble those in a Woman. In the Uterus with Horns, the changes are accord- ing to the number of Foetuses the Mother carries. In Uniparous Animals, as the Mare, the Foetus is confined to the Uterus. In the Cow, it extends from the Uterus to one of the Cornua. In Multiparous A- nimals, one or more Foetuses are contained in each Horn ; in which last case, the Cornua, by their alter- nate contractions and dilatations, are formed into Cells. The Uterus Anfractuosus has the fhinnest Coats of any, and suffers the least change by Impregnation. In the Kanguroo after Impregnation, the communication be- tween the Vagina and Lateral Canals is completely shut up by inspissated Mucus. A minute orifice is describ- ed as being now close to the Urethra, and communicat- ing with the Uterus, though no opening is found here in the virgin state. This dilating at the time of par- turition, is found to discharge the Foetus into the Pouch, or False Belly; the parts, after delivery, re- turning to their original state. In the Opossum, the changes by Impregnation are not yet ascertained. The connection between the impregnated Uterus and surfac e PART L] OF MAMMALIA. 159 surface of the Ovum is effected, in Mammalia, in three different ways. 1. In some, as in the Mare and Sow, the whole ex- ternal surface of the Ovum adheres to the Uterus firm- ly, or a bag-like Placenta is formed. 2. There is a simple Placenta, Orbicular in some, as in the Ape tribe and most of the digitated Mammalia, or forming a Zone or Belt, as in the Dog and Cat kind, &c. In several of the digitated Mammalia, the external surface of the Placenta has a white Glandular-like Body, or Corpus Glandulosum, inclosed in it, which admits of the easier separation of parts towards the latter period of Gestation. 3. A third kind of connection is found in Ruminants, where there are numerous Placentulee, or Cotyledons % upon the surface of the Ovum. These adhere to Glands, produced from the inner side of the Uterus. The Glandules Uterinae have many Papillae and Ca- verns, corresponding to Caverns and Papillae or Pro- cesses of the Placentulae. They are very Vascular, and possess a milky-like Liquor, which can be readily squeezed out from them ; but no injection can be made to pass from the Vessels of the Placentulae to those of the Glandular. The Cotyledons and Gland ulae adhere to each other, the former inclosing the latter, from which comes their name; but they can be readily separated from each other at the latter period of gestation. The Cotyledons are discharged with the After-birth, the Glandulae gradually diminishing in size after the contents of the Uterus have come away, but exist in the Uterus both in the gravid and unimpregnated state. K 4 The 160 OF THE FEMALE ORGANS [PART L The number and form of these excrescences vary in different Animals. In the Sheep and Cow, they are from seventy to a hundred. In some Animals, they are concave externally ; in others, convex. The Involucra of the Foetus consist of the outer Membrane, or Chorion, and the inner one, or Amnios, that secretes the liquor in which the Animal swims. The two Membranes, contrary to what happens in the Human Species, are covered with Blood-vessels derived from those of the Umbilical Cord. Between the Chorion and Amnios, in most pregnant Mammalia, the Cetacea not excepted, there is an Al- lantois, or Bag, but destitute of Blood-vessels, which receives the Urine from the Bladder by a Canal termed Urachus. In Solipeds, the Aljantois is every where interposed between the other two Membranes. In the Cow and Sheep, it covers only part of the Amnios ; and in the Sow, it covers only a small part of that Membrane. In the Marc and Sow, there is a fleshy-like mass con- tained in the Allantois, which has been considered by some as the sediment of the Urine, and termed Hippo- manes, or Horse-venom, the nature of which is imper- fectly understood. The Allan tois is wanting in the Ape kind, and in the Hedge-hog, Dog, Cat, &c. in which is found a Mem- brane, termed Tunica Erythroides, which contains a watery fluid at the commencement of pregnancy, and is connected to the Mesenteric Vessels of the Foetus, but has no Urachus. Like the Vesicula Umbilicalis in the Human Foetus, this is more immediately connected with early pregnancy* The PART!.] OF MAMMALIA. 161 The Umbilical Cord is observed to be proportionally shorter in Quadrupeds than in the Human Species. In most of them, there are two Umbilical Veins, united into a Trunk near or within the Body of the Foetus. In the Foal, the Cord has only a single Vein. OF THE FCETUS, AND ORGANS WHICH NOURISH IT FOR SOME TIME AFTER DELIVERY. The peculiarities of the Foetal Quadruped, with re- spect to structure, are not much different from those in the Child at the end of pregnancy. The number of young produced at a time varies ac- cording to the kind, and is observed to be greater in tame than in wild Animals, as in the Sow and Cat. The Whale produces only a single Foatus at a time, and once in two years. In suckling, she turns almost on her back on the rim of the water. The nourishment of the Foetus, in Mammalia, is derived from the Mother's Milk, which is secreted from the Mamma, and is peculiar to the Animals of this class. The situation and structure of the Mamma vary ac- cording to the number of Fretuses the Animal produces at a time. In Uniparous Animals, they are generally situated between the Hind Legs. In the Multiparous, they extend, in some, along the Abdomen, and in Others, also along the Thorax. The Mamma is sur- rounded with less Fat in proportion than in Women ; Jience not bulky, till distended with Milk. The situation and number of the Teats projecting from 162 OF THE FEMALE ORGANS [PART I. from the Mamma vary much. In general, though with many exceptions, the number is about twice that of the Foetuses the Animal commonly produces at a Birth, to give, along with the extended Mamma, an opportunity for suckling all the young at the same time. The Teat is commonly hollow within, the Cavity communicating with two reservoirs, in which the Lac- tiferous Tubes terminate. It has only one or two ori- fices externally. Of the number of the Teats in Mammalia, there are generally, Two Inguinal in the Sheep, Goat, Marc, and Cetacea. Four Inguinal in the Cow, Deer, and Camel. Four Abdominal in the Lioness and Panther. Ten Abdominal in the Sow* Six Abdominal, and Four Pectoral, in the Bitch, Hare, and Rabbit. Four Abdominal, and Four Pectoral, in the Cat. Eight Abdominal, and from Two to Four Pectoral, in the Eat. Two Abdominal, and Four Pectoral, in the Bear. Four Abdominal, and Six Pectoral, in the Hedge-hog. Two Pectoral in the Ape, Bat, and Elephant. The Nipples are sometimes found, but in smaller number, in the Male, as in the Dog ; or in a different situation, as on the sheath of the Penis in the Horse ; and there arc numerous instances where Milk has been secreted in the Mammae of Male Animals, as the Dog, Cat, &c. ; and Milk, or a fluid similar to it, is com- monly found in the Mammae of newly-born Quadrupeds of both sexes, as well as in the Breasts of Children. la PART I.] OF MAMMALIA. 163 In the Marsupial Animals, as the Kanguroo and O- possum, there is a Bag or Pouch, formed by the Com- mon Integuments, and lined thinly with Hair. It is connected with a pair of Bones arising from the Pubis, which have Muscles for raising them, and the Pouch along with them. It is closed by a Sphincter Muscle, and opened by its own relaxation, or by a Muscle which draws the Pouch towards the Vulva, to receive the young at the time of delivery. Whether the Embryo ever possesses an Umbilical Cord, or a connection with the Uterus similar to that in other Quadrupeds, is not ascertained ; nor is the exact time at which the Fostus enters the Pouch been hitherto pointed out ; but it is observed, that at an early period of pregnancy, the Foetus, scarcely an inch in length, passes from the Uterus through the Vulva into the False Belly, where it adheres by its Mouth to one of the Nipples placed there for its nou- rishment. When the Animal arrives at a certain de- gree of maturity, it goes out of the Pouch and re-enters it at pleasure, till it has acquired strength enough to provide for itself. (See MR HOME'S Paper on this sub- ject in Phil. Trans. 1795.) *$o False Belly is found in the Male of these Animals, PART PART IL OF BIRDS, OF THE BONES. 1 HE Skeleton of Birds has a considerable uniformity in the whole class, and bears a strong analogy to that of the Mammalia ; but the large Bones, in Birds of whatever shape, are destitute of Marrow in their inter- nal Cavities, in place of which they contain air, and communicate with the Lungs by considerable apertures. Foetal Birds, however, or such as have just quitted the Shell, have their Bones filled with Bloody Marrow, which, in general, is soon absorbed, and, in Aquatic Birds, the greater part disappears. The Scull 9 in this class of Animals, has no Sutures, at least in the Adult state, but is in a manner consoli- dated into one piece. In young Birds, there is a kind of False Sutures, but these are soon obliterated. The Cranium is of a Cellular texture, and particularly so in some, as the Eagle and Owl, by which the strength and bulk of the part is increased, and the Body rendered specifically lighter. Some Birds are remarkable for a Crest or Horn on the upper part of their Head. Emi- nences of this kind are united with the Frontal Bone, and BART II.] OF BIRDS. 165 and may be considered as enlargements of the Orbitar Portions. The Cavity of the Cranium is divided into two prin- cipal Fossce, one for the Cerebrum, the other for the Thalami Optici, Cerebellum, and Medulla Oblongata. The number of the Bones of the Cranium is nearly the same originally as in the Human Body. The Orbits are of great size. In some, they are separated by a Membrane ; in others, by a partition more or less Os- seous. The Temporal Bones have no Zygomatic Pro- cesses. The Cranium, in the whole of the class, is joined to the Bones of the Neck by a single hemispherical Con- dyle, placed at the fore part of the Foramen Magnum. The relative magnitude of the Cranium and Jaws varies much in Birds. In some, as the Owl, the Bill bears a small proportion to the large Cranium ; in others, as the Rhinoceros Bird, it is of an extraordinary size. The Nasal and Palatine Openings also vary much in different Birds ; in the Stork, they are small ; in the Crane, remarkably large. The Upper Jaw, or Mandible, in most Birds, is more or less moveable. It either constitutes a particular Bone articulated with the Cranium, as in the Parrot kind, or is united with it into one piece by means of elastic Bony Plates, as in Birds in general. It is immoveable in a few, as in the Code of the Wood, and the Rhinoceros Bird. The Teeth are wanting in the different individuals of this class, the Bill supplying their place, yet acting like the Fore- teeth of those Animals that use them for seiz- ing their prey* All 166 OF THE BONES [PART IL All Birds have a Bone termed Os Quadratum, by which the Lower Jaw is articulated with the Cranium on both sides. Another small Bone is connected with it, and rests by its opposite end against the Palate, in such a manner as to elevate the Upper Jaw when the Square Bone is carried forwards by its Muscles. The Os Hyoides is divided, as in Mammalia, into a Body and two Cornua, which are of a round and slen- der form. The number of the Vertebra is as variable as in Qua- drupeds. In the Neck, they are numerous, and vary more than in the other parts of the Spine, the number depending upon the length of the Neck. The smallest number of Cervical Vertebrae is found in the Spjzrrow, and the greatest in the Swan, the one having only nine, while the other has twenty- three. The Dorsal Verte- bras are fewest in the Bullfinch, being only six in num- ber, and most numerous in the Swan, which has eleven. The Lumbar Vertebrae are united into one piece. The smallest number of Sacral Vertebrae exist in the Coot, there being only seven, while the Ostrich has twenty, which is the greatest. The Turkey and Pheasant pos- sess the smallest number of Caudal Vertebras, viz. five. The greatest number is found in the Starling, Swallow, and Ostrich, which have nine. Each of the Bodies of the Cervical Vertebras forms a part of a Cylinder, in consequence of which they are allowed free motion. The three or four uppermost Vertebrae can only move forward, and the rest backward, the whole giving the form of an/j but by contracting or widening the two Arches^ PART II.] OF BIRDS. 167 Arches, they can shorten or lengthen the Neck readily. The Atlas has the shape of a ring, and is only connect- ed with the Head by a single articulation in the form of ball and socket. From the whole of this structure such motion is allowed, that Birds have the peculiar power of placing the Bill under the Wing when they rest. The Dorsal Vertebrae have the Spinous Processes tied together by strong Ligaments, and they are often united into a solid mass. The Transverse Processes send off two points, one forwards, the other backwards, which join those of the other Vertebrae, and the parts here are sometimes also anchylosed ; but in Birds that cannot fly, as the Ostrich and Cassowary, the Vertebrae remain moveablc. The Lumbar Vertebrae are commonly ossified toge- ther, and also to the Bones of the Sacrum and Pelvis, so as to give the appearance of a single Bone. The two lateral parts of the Pelvis do not close before to form a Symphysis Pubis, excepting in the Ostrich. There is generally a Foramen Thyroideum, and the Ischiatic Notch is formed into a complete Foramen. The Caudal Vertebrae are found in greatest number in Birds which move their Tail most freely, as the Magpie and Swallow. The last Vertebra of the Tail is the largest, and is often in form of a plough-share, for the attachment of the Quills. In the Peacock, it is of an oval form, and situated horizontally. The Thorax, in Birds, is commonly remarkably large in proportion. The Ribs have several peculiari- ties in their form and attachments. Their Vertebral Extremity 168 OF THE BONES [PART II. Extremity is forked, one of the Branches resting upon the Body of the Vertebra, the other upon its Trans- verse Process. The Sternal Extremity has an Osseous Appendage supplying the place of Cartilage. The middle of the Rib has a flat Process directed upwards and backwards over the following Rib, .each in this manner supporting the other. The number of the Ribs is less than in the Human Body 5 they are not found to exceed ten pairs. The Sternum is of great proportional size, covering not only the Breast, but a large part of the Belly. In- ternally it is concave, externally convex, and is ex- tended below into a ridge termed Crista, resembling the keel of a ship. This, with the under surface of the Bone in general, serves for the attachment of the very strong Pectoral Muscles that move the Wings. In some Birds, as the Ostrich and Cassowary, which Lave not the power of flying, the Sternum is flat below, and there is no Crista. The Wings are connected to the Sternum by three Bones, viz. two Clavicles, and the Furcula, Fork-like Bone, or Merry-thought. The Clavicle is articulated with the anterior edge of the Sternum, and has little motion. It is divided into two short Processes, one connected to the Furcula, the other to the Scapula, with which it forms a Cavity for the reception of the Humerus. The Furcula is peculiar to Birds, and is seldom wanting. It is in form of a V, common to both Shoulders, and is joined by its point to the most pro- minent part of the Crista of the Sternum, while the other extremities are connected to the Humeral end of the PARTI!.] OF BIRDS. 169 the Clavicle, and the point of the Scapulae where these two Bones are articulated with each other, and with the Os Humeri. The Furcula serves to keep the Wings at a proper distance in flying, and is strong and expanded in Birds which fly with great force and rapi- dity. In the Ostrich and Cassowary, it is imperfect, the lateral Branches not uniting together. The edge of the Scapula, in Birds, is long next the Vertebrae, and the Bone is always destitute of a Spine. The Wings, or Superior Extremities, consist com- monly on each side of an Os Humeri two Bones of the Fore-arm two of the Carpus, one of which is Radial and Rhomboidal, the other is Ulnar, wedge-shaped, and has a Tubercle, which is sometimes a separate piece, cor- responding with the Os Pisiforme in Mammalia two generally consolidated into one piece in the Metacar- pus one in the Thumb two Fingers, that next the Thumb long, consisting of two Portions, the other has only one. The Os Humeri is articulated with the Clavicle and Scapula, and below has two Articular Pro- cesses, as in Man. The Radius and Ulna move freely on the Os Humeri j but the Radius cannot turn upon its own axis. Upon the First or Long Finger, and the Metacarpal Bone, the Primary Quills are placed. The Thumb sustains the False or Bastard Quills. The size of the Bones of the Wings varies as occa- sion requires. In Birds of prey 3 which have to carry their Food frequently to a considerable distance, and other* which fly tar, the Bones of the Wings are of great length ; while in domestic Fowls, &c these Bones are >iaall in proportion to the size of their Bodies. OL. IV. L The 170 OF THE BONES [PART II. The Bones in the Wings of the Penguins are remark- able for their flattened appearance, and form a sort of medium between the Wing of the Bird and the Fin of the Fish. In the Lower Extremities, there is an Os Femoris, a Tibia, a Fibula, which is soon anchylosed to the Tibia, and does not reach its Lower Extremity ; a Rotula, the place of which is often supplied by a Process of the Tibia, as in Diving Birds ; one Bone supplying the place of Tarsus and Metatarsus ; and the Toes, the Bones of which are more numerous, the more exterior- ly they are placed. The Toes are articulated upon a Pulley formed by the lower end of the Metatarsal Bone. The inner side has a small Bone, that supports the Pos- terior Toe or Pollex. There are two Bones to the Pollex, three to the Second Toe, four to the Third Toe, and five to the Fourth. In Birds with only three Toes, the First Toe has three, the Second four, and the Third Toe, five Bones. The Cassowary has only three Toes, and the Ostrich two. The Birds with four Toes have commonly three before, and one behind. Some, as the Parrot, Cuckoo, &c. have two before and two be- hind. Swimming Birds, as the Penguin, have the Pol- lex obliterated. In wading and other long-limbed Birds, the length of the Leg is produced by the Tibia, and the Bone which supplies the place of Tarsus and Metatarsus 5 and is often in proportion to that of the Neck, though there are many exceptions. The Lower Extremities of Birds in general, are placed so much behind the icomraon centre of gravity, as to make the Animal ap- pear PART II J OF BIRDS. 171 pear to be in danger of falling forward in walking ; but this is prevented by the angle formed between the Leg and Body, and by the elevation of the Head and Neck. OF THE MUSCLES. 1 HE Muscles of Birds are peculiar, in having their Tendons converted into Bone as the Animal becomes old. Of the Muscles of the Head, there are three in each side, which serve instead of the Digastric for depressing the Lower Jaw. They are distinctly seen in the Duck, but one of them is frequently wanting in other Birds. There are three, also, for closing the Bill, one of which supplies the place of the Temporal and Masseter, the other, that of the two Pterygoid Muscles. The Os Quadratum has three pairs on each side, which assist also in the opening and shutting of the Bill. In the Turkey, the Os Hyoides has Muscles analo- gous to the Mylo-hyoid, Stylo hyoid, Stylo-glossus, Ge- nio-hyoid, and -Cerato-hyoid, for acting upon this Bone and the Tongue. The Tongue has three pairs fixed into it, which arise from the Os Hyoides. There are no Muscles peculiar to the Pharynx ; it has Muscular Fibres common to it and the Esophagus. The Splenius and Obliquus Superior are wanting, L 2 :but 172 OF THE MUSCLES [PART II. but there is an additional Rectus Posticus, viz. a Maxi- mus. The Muscles of the Dorsal part of the Spine are also wanting, the parts here being quite rigid. The Neck is furnished with a number of Muscles, corresponding with the number of the Cervical Vertebrae. The Tail has Muscles for raising, depressing, and turning it to either side. They arise chiefly from the posterior part of the Trunk of the Body, and are fixed to the Os Coccygis. The Lateral Muscles in particular, acting together, expand the feathers in the Tail, so as to pro- duce that beautiful fan-like appearance, so remarkable in the Turkey, Peacock, and Pheasant. Of the Muscles of the Ribs, the Scalenus is analo- gous to the Levatores Costarum, which extend from the Transverse Processes of the Vertebrae to the ante- rior edges of the Ribs. The Intercostales and Trian- gulares bear a considerable resemblance to those in Man. Birds have no Diaphragm. There are three Layers of Abdominal Muscles, the two outer of which run more in a transverse direction than in the Human Species. The Recti and Pyramidales are wanting. Muscles of the Superior Extremity. The Muscles of the Scapula are the same in number with those in Mam- malia ; but the Trapezius and Rhomboides are small, their origin being chiefly confined to the Spine of the Back. Birds have three Pectoral Muscles, all arising from the very large Sternum, and fixed to the Scapu- jary extremity of the Humerus. The First, or Great Pectoral, with its fellow, which weighs more than all the other Muscles taken collectively, arises from the Os Furciformej *ARTlL] OF BIRDS. 1?3 Fnrciforme, the Keel of the Sternum, and the last Ribs, and is inserted into a prominent Linea Aspera of the Os Humeri. By depressing this Bone, the Muscle produces the quick and powerful motions of the Wing in flying. The Second, or Middle Pectoral, is situated under the former, and sends a Tendon over the union of the Scapula, Fork, and Clavicle, as over a Pulley, to ele- vate the Humerus, and balance the Animal in its flight. The Third, or Smallest Pectoral* arises from the late- ral angle of the Sternum and base of the Clavicle, and brings the Humerus close to the Body, in which mo- tion it is assisted by two small Muscles passing between the Clavicle and Head of the Humerus. By the action of these three Muscles, the alternate motions are pro- duced of raising and depressing the Wing, by which the Bird is carried forward in flying. By the strength of the Tail the Animal is kept in a proper balance, and prevented from falling forward. The Latissirnus Dorsi is formed of two portions, one fixed under the Head, and the other at the middle of the Body of the Humerus. The other Muscles of the Scapula are nearly as in the Human Body. The Biceps has one origin from the Scapula, and another from the Os Humeri, and is inserted into the Ulna. The Bracheus arises from the Linea Aspera^ and is fixed to the inner side of the Head of the Ulna. There is another Flexor, which arises from the Exter- nal Condyle of the Humerus, and, after extending some way along the upper part of the Ulna, is fixed to the outer part of that Bone. The Extensor Cubiti is composed of two portions, one from the Scapula, the L 3 othep 174 OF THE MUSCLES [PART R other from the Humerus. There is also an Anconeus. The Supinator Longus is wanting. There is a kind of Supinator Brevis, but it is considered as bending the Fore-arm. Two Muscles occupy the place of the Pro- nator Teres, though seemingly acting as Flexors. The Metacarpus possesses only the motions of adduc- tion and abduction. The Muscles for performing these motions are the following : The Ulnaris Interims, which arises as m Man, and is fixed to the wedge -like Bone of the Carpus ; another Muscle lying under this, and sending off a long Tendon, which gives slips to the se- condary Quills, and is inserted to the back of the Me- tacarpus , the Ulnaris Externus, which is placed on the posterior surface of the Ulna j its Tendon, passing between the last Primary Quill and first Secondary one, and inserted to the inner edge of the base of the Meta- carpus ; a Radial Muscle, which arises by different portions from the External Condyle, and one from the Radius, their common Tendon being fixed to the Tu- bercle of the Metacarpal Bone of the Thumb. The Digital Muscles, also, can only perform ad- duction and abduction. Of the Adductors or Ex- tensors, there is the Adductor Phalangis Primse, which corresponds with the Flexor Sublimis, arises from the Internal Condyle, and is fixed to the base of the first Bone of the Great Finger. The Ad- ductor In tern us Phalangis Secundae, which corre- sponds with the Flexor Profundus, and goes along the inner side of the Radius, and is inserted into the base of the second Phalanx. The Adductor Pallia's, which corresponds to the Flexor Pollicis, is situated between the ART II.] OF BIRDS. 175 the preceding Muscle and Ulna, and sends a Tendon to be fixed to the radial edge of the Thumb. The Ad- ductor Externus Phalangis Secundae, which is analo- gous to the Flexor Proprius Indicis, arises from the External Condyle, having its Tendon fixed to the back of the Metacarpus and second Phalanx of the Great Finger. Muscles of the Pelvis and Inferior Extremity. The Psoas Parvus and Magnus, the Iliacus Internus, and Quadratus Lumborum, are wanting. There are two Ad- ductor Muscles of the Thigh, situated as in Mammalia, and a Muscle analogous to the Pectineus, which is conti- nued to join the Flexor Perforatus of the second and fifth Toes. The three Glutei have the same proportions as in Quadrupeds. The Pyriformis and Gemini are wanting* The Muscle analogous to the Quadratus Femoris is re- markable for its great size. The Obturator Internus goes over the Hole analogous to the Foramen Thyroi- deum. The Extensors of the Leg are nearly as in Quadrupeds. Of the Flexors, there are two somewhat analogous to the Biceps and Semi-membranosus $ a third which is intermediate, but is sometimes wanting, particularly in Birds of prey ; and a fourth, which forms the anterior part of the Thigh, and is similar to the Sartorius. The Tendons of the Gastrocnemii re- main separate to near the Heel. The Soleus is fixed to a Linea Aspera, which belongs to the Tibia. There is a Peroneus Brevis, and a Muscle analogous to the Pe- roneus Tertius in Man. There is an Extensor Longus of the three Ante- rior Toes, corresponding to the Extensor Longus L 4 Digitorum, 17* OF THE MUSCLES [PART If, Digitorum. The Extensor Longus Pollicis is want- ing; four small Muscles supply the place of the- Extensor Brevis ; a Flexor Brevis Pollicis is situat- ed in the back part of the Tarsus ; there are long Flexors, of the Toes, which are divided into three masses ; these come partly from the Os Femoris, and partly from the Bones of the Leg. They have connect- ed to them an Accessory Flexor, which comes from the Pubes, and sends a Tendon over the Knee. The diffe- rent Tendons run under the Heel, and are united by Fibres to each other ; and one set of Tendons perforate another, and are fixed to the different Phalanges of the Toes. By this mechanism, the Bird is supported, or can lay hold of Branches of Trees, &c. when roosting ; the weight of the Body giving that degree of flexion to the Knee and Heel, which produce* the necessary con- traction of the Toes. By this contrivance, also, Ra- pacious Birds seize their prey while pouncing on it. When they wish to disengage themselves, they do it readily by raising the Body, after which the Toes are expanded. OF THE INTEGUMENTS. 1 HE Integuments consist of the same parts as in Mam- ttialia. The Cuticle is very thin, and, in the Le$_s and Feet, PARTlL] OF BIRDS. 177 Feet, is generally formed of Horny Scales, which fall off in moulting-time. The Corpus Mucosum is not very distinct. It varies in colour in different parts of the Body. In the Legs and Feet, almost all the different colours are to be ob- served in the different individuals of the class. The Cutis is much thinner than in Quadrupeds, but has considerable thickness in Birds of prey. The Pa- pillae Nervosae, and sense of feeling in the Integuments of Birds, reside only in the Feet and Toes, the Supe- rior Extremities being generally covered with Feathers. Even in the Lower Extremities of some, the Legs and Toes are frequently covered with Scales or Feathers, so as to blunt the sense of Feeling also in this part of the Animal. The Cellular Substance immediately under the Skin, adheres loosely to the parts directly above and below it, but particularly at the Axillae. In certain Birds, as the Swallow, the Subcutaneous Cellular Substance is deprived of Fat, though the Pe- ritoneum is charged with it in the winter-season. From the surface of the Skin, Excretions take place, as in the former class of Animals, as appears in moult- ing, and from a quantity of mealy dust being separated in pairing-time. Besides the Layers of the Skin mentioned above, Birds have a Panniculus Carnosus, which is more dis- tinct in certain kinds, as those which raise their Fea- thers in particular parts of the Body. Besides one broad Muscle, there are Slips which run in different directions, 178 OF THE IiVTEGUMENTS [PART It directions, and act upon the Skin and Feathers over them. The Feathers are the peculiar covering of Birds. They protect them from the inclemency of the weather, and serve them for flying. In Water Fowls, the Fea- thers are besmeared with an oily fluid, which prevents the water from injuring them. Upon certain parts of the Integuments there are Glands, that separate an oily matter, with which they anoint their Feathers. These are found under th<* Skin of the crop ; but the greater part of this substance is discharged, by one or more orifices, from a Gland si- tuated upon the Rump. With the contents of this the Duck, by means of the Bill, besmears the Feathers frequently. The Feathers are wanting in young Birds. When they first leave the Egg, they are covered with Hair, formed into Fasciculi, each of which grows from a common Bulb, that gives origin to the future Feathers, The Hair is soon succeeded by Sheaths, giving pas- sage to the Feathers, the inner ends of which are sup- plied with Blood-vessels, that form first the Barrel, then the Stalk of the Quill. The Feathers are at first composed of a Pulpy sub- stance, inclosed in Cells. The Pulp is by degrees ab- sorbed, and the part assumes the appearance of a Cor- pus Cavernosum. The Stalk is convex on one side,, and concave, and furrowed in the middle, on the other. Upon the sides of the Stalk are Barbes, composed of Horny Lamina?, and beset laterally with Hairs or Bar- bules. The Feathers on the Wings and Tail are term- ed PART II.] OF BIRDS. 179 ed Pens or Quills ; those on the Bones, analogous to the Fore-arms, are termed Secondary. The Feathers vary exceedingly in appearance in dif- ferent Birds. Some, as the Turkey, Raven, &c. are covered with Hairs in particular places. The Feathers of night Birds of prey are covered with Down, while those of other Birds are garnished with a kind of silk. Some Birds have Feathers not only on their Bodies, but also on their Feet ; and some, as the Mow Game, have them on their Feet in the winter season only. Some, as the Vulture and Turkey , want them on the Head. Several have two or more Feathers arising from a common Quill. In the Penguin kind, the Feathers of the Wing are in the form of small Scales. In the Cassowary, they are like the Quills of the Porcupine, being destitute of Barbules. The Feathers of Birds are annually changed, or there is a moulting-season ; but all Feathers are not found to fall at the same time. In several Birds, where the Male and Female have different Plumage, it is observed that the latter, after ceasing, through age, to lay Eggs, assumes the Plum- age of the Male. Birds have Claws commonly on the Toes ; and in Birds of prey, they are strong, like those of Carnivo- rous Quadrupeds. In Gallinaceous Birds, there is a supernumerary Claw, the Spur, which the Animal uses in fighting, and in fixing upon the Female in discharging the Se- men, The OrnithorrimcJms has a Spur for the same purpose. ISO OF THE INTEGUMENTS [PART II. purpose. In the former Animals, the Spur has one Bone in it, which is fixed to the Tarsus ; in the latter Animal, it has two. Claws are wanting in the Wings of Birds, where they could not be used either for walking, or seizing the prey. OF THE BRAIN, $c< THE Membranes of the Brain correspond in numbed and general appearance with those of the former class. In some Birds, there is even a Falx, and this, in the Wood-code and Ornilhorrynchus, is of an Osseous na- ture. The proportional she of the Brain of the Animals of this class varies extremely ; but it is found, that the Brain of the smaller Birds bears a greater proportion to the size of the Body than that of the larger kinds. While, in the Sparrow, it is a 25th, and in the Gold- Jincli) a 14-th of the weight of their Body 5 in the Eagle, it is only a 160th, and in the Goose, a 360th. The Brain consists of two large masses, which form the Hemispheres, the two Thalami Optici, the Cere- bellum, and Medulla Oblongata. The Hemispheres are in form of a Heart, with the base turned backward. There are no Convolutions, nor Corpus Callosum, nor Fornix, nor Septum Lu- cidum. PART II.] OF BIRDS. 181 cidum. The Corpora Striata are of uniform colour in- ternally. The Thalami are two roundish Tubercles lying un- der the Hemispheres, without being inclosed by them, Between the Thalami and Corpora Striata are com- monly four Eminences, which do not appear in Man. The Lateral Ventricles do not turn down behind to form the inferior Cornua ; of course, the Cornua Ammonis are absent. The Lateral Ventricles, in Birds, are distin- guished from those of all other Animals, by the radiated partition which separates them from each other. They communicate with each other, and with the Third Ven- tricle. The Third Ventricle -is situated between the Thalami, and communicates with the Infundibulum, and also with the Fourth Ventricle ; but the passage into this last is only covered by a thin Lamina, the Tubercula Quadrigemina being either absent or indistinct, though the Pineal Gland is present. In each of the Optic Thalami, there is an additional Ventricle, which opens into the passage leading from the Third to the Fourth Ventricle. The Cerebelkfin is only a simple Lobe ; it has, how- ever, transverse Striae, somewhat similar to those in Mammalia. The Fourth Ventricle has also, as in that class, a Calamus Scriptorius, and an Arbor Vitae ; but the latter is more simple than in Mammiferous Ani- mals. The Po?i$ Varolii is wanting. The Medulla Oblon- gata has no Eminences, such as are seen in the former Ho.ss of Animals. NERVES. 182 OF THE BRAIN, &c. [PART II. NERVES. The Cerebral Nerves are the same in number as in Mammalia. The Olfactory, after leaving the Brain, goes in a distinct Canal to the cavity of the Nose. The Second crosses its fellow, and goes to the Eye of the op- posite side. The Third, either by a hole peculiar to it, or by a Sphenoid Fissure, passes to the Muscles, as in Mammalia. The Fourth is also as in the former class. The Fifth divides as in Mammalia. The Branches to the Beak correspond with those about the Jaws in Mam- miferous Animals; but those to the inner side of the Nose are of great magnitude, and run to the extremity of the Bill, in Birds which search for their food in water, mud, &c. The Sixth are as in Mammalia. Of the Seventh, the Portio Dura is proportionally small, the Lips being absent, and much of their Bill being Horny and Cal- lous, and not requiring a great supply of Nerves. The "Portio Mollis, of great size, goes to the Labyrinth by many Branches. The Eighth and Ninth pairs are dis- persed as in Mammalia. The Great Sympathetic has origins, connections, and terminations, which bear a considerable analogy to those cf the Animals of the former class, varying only in some particulars. It passes through the same Foramen with the Pars Vaga and Glosso-pharyngeus. It unites with Nerves near it, has Ganglia in its course through the Body, and can be traced as far as the Vertebrae of the Tail. The Spinal Marrow is nearly of the same nature, and the ] OF BIRDS. 183 the Nerves are generally sent off from it by anterior and posterior bundles of Fibres, as in Mammalia. The Cervicals are analogous to those of the former class of Animals, but the number corresponds with that of the VertebraB. They go chiefly to the Neck, only one or two of the last assisting in the formation of the Brachial Plexus. The Diaphragmatic Nerves, like the Diaphragm it- self, are wanting. The Dorsals and Lumbars correspond with those in Mammalia, and the number with that of the Verte- brae. The Bracliial Plexus is chiefly formed by the last Cervical and two first Dorsals, and is large, having to supply the Pectoral Muscles of great size, which are inserted into the Wings. The Nerves of the Abdominal or Inferior Extremities are nearly as in Mammalia. The Anterior Crural is sent off from the three last Lumbars, from which comes also the Obturator. The Sciatic is chiefly formed by the four Superior or Anterior Pelvic Pairs, and divided somewhat as in Mammalia, the last Branches dividing jnto others according to the number of the Toes. OF THE EYE. 1 HE Eyes are larger in the individuals of this class, in proportion to the size of the Scull, than in Mammalia, and 18* OF THE EYE [PART II. snd are placed so much in a lateral direction, that the Animal, in viewing objects particularly, turns towards them one side of the Head, and examines them with a single Eye. The Orbits are more shallow here than in Quadru- peds 5 of course, the cushion of Fat surrounding the back part of the Eye is thinner. In most Birds, as Fold, Duck, Turkey, &c. the Eye- lids are closed by the Orbicularis elevating the Inferior Palpebra, which is the largest, and has a small Lamina of Cartilage. There is a peculiar Muscle arising from the bottom of the Orbit, for depressing this Eye-lid. In a few, as the Parrot^ Owl, Goat-sticker , OstricJi 9 &c. the Upper Eye-lids are most moveable. Cilia are found in a few Birds only, as some Parrots and Hawks, the Ostrich, &c. Besides the two ordinary or horizontal Eye-lids, Birds have a third one placed at the .Nasal Angle, and termed Membrana Nictitans, which is a semi- transpa- rent Membrane, capable of covering the whole Eye. In a state of rest, it is scarcely observed, but can be drawn out by the action of two Muscles, so as to cover the whole front of the Globe. The Muscles performing this motion arise from the back of the Sclerotic. The one, termed Quadratus, has its origin from above ; the other, called Pyramidalis, comes from below, and forms a Tendinous Cord, that runs through an Aponeurotic Sheath formed by the first, then in Cellular Substance at the under part of the Sclerotica, to be fixed to the inferior and exterior edge of the Hembrana Nictitans. II.] OF BIRDS. 185 After the Membrane has been drawn to the outer cor? ner of the Eye, it is returned by its own elasticity. The Lacrymal Gland, in Birds, is commonly small. It is situated at the outer angle, and sends out the ^Tears in some, as the Common Fowl, by one, and in others, by two or three small Canals, through the Up- per Eye-lid. The Glandula Harderi is also found here ; it is of a fleshy dolour, and considerably larger than the Lacry^- mal Gland. It is commonly placed between the Le- vator and Adductor Oculi, and discharges, by a single Duct, a yellowish fluid upon the inner surface of the third Palpebra. In the Duck tribe and the Water Birds, there is a large Glandular Body in the upper part of the Orbit, which seems to supply the place of the Lacrymal Gland, yet no Duct has been traced from it. All Birds have two Puncta Lacrymalia, but no Ca- runcula Lacrymalis. The passages from the Puncta terminate in the Nasal Sac, situated in the Palate, at the base of the Nose. The Sclerotic Coat forms little more than a hemi- sphere in this class, and to its anterior flat part is at- tached the Cornea, making a section of a smaller globe. In consequence of the flatness of the anterior part of the Eye, it is prevented from being injured when the Animal is scrambling among bushes, or taking a rapid flight through the air. The fore part of the Sclerotis divides into two Lami- nae, between which there are numerous Osseous Plates, which overlap each other, and form a Ring, commonly VOL, IV. M flat, 1S6 OF THE EYE [PART II flat, but sometimes convex, at other times, as in the Owl, concave. The Choroid Coat has no Tapetum, such as is found in many Quadrupeds. The inner side is uniformly blackish, and lined with Mucus , which prevents Birds from seeing distinctly in the dark. All Birds have Ciliary Processes, but they project so little, that they appear rather like Striae than loose Folds, and are connected to the Crystalline Lens. The boundary between the Choroides and Iris is dis- tinctly defined in this class. The Iris varies in appearance according to the Spe- cies. It is blue, red, or yellow, and commonly pos- sesses great brilliancy. In some, as the Parrot, the motions of the Iris are voluntary. The Animal can dilate or contract the Pu- pil at pleasure. A Membrana Pupillaris is not observed in Fo3tal Birds. The Optic Nerves run here in such a manner, that it is difficult to distinguish any union in them. Upon reaching the Ball, each goes through a Sheath of the Sclerotic Coat, and then forms a round white line, from which grows the Retina. In the internal part of the Eye, there is a Membrane of a most delicate texture, somewhat resembling the Choroid Coat, and termed Marsupium Nigrum, Peclen, or Membrana ilicaia, from its colour and plaited ap- pearance. It arises in the bottom of the Eye, at the entrance of the Optic Nerve, passes obliquely through the Retina, and terminates at or near the edge of the Crystalline Lens. It is formed of Plicae, varying in number PAR* II.] OF BIRDS. 187 number in different Birds, and is of a conical form, very Vascular, and covered with a black paint. In the Ostrich and Cassowary, it forms a kind of conical purse, whence the French term it Bourse Noire. It is sup- posed to absorb rays of light when too strong, or when the Animal attempts to look at near objects. ,And some have considered it as serving to move the Lens ; but Muscular Fibres have not been detected in it, and its oblique situation is also unfavourable to this. The Humours of the Eye are analogous to those in. the former class. The Lens is flatter or rounder, in an inverse ratio to that of the Cornea. In Land Birds> it is flat, as in Mammalia ; in the Aquatic, it is more of a globular form. The Muscles of the Eye, in Birds, are the same in number as in the Human Body ; but both the Obliqui come from the fore part of the Orbit, near each other. One is inserted below, the other above, without going through a pulley, as in Mammalia. The whole Muscles of the Ball are fixed to the soft part of the Sclerotic, behind the Osseous Laminae, and are shorter in pro*- portion than in the former class. This, together with the flat shape of the Ball, allows very little motion. The Suspensory Muscle existing in Quadrupeds, is wanting in Birds. M2 OF JS8 OF THE EAR [PART OF THE EAR. 1 HERE is no Cartilaginous External Ear in any of the class, but instead of it, especially in Rapacious Birds-, there is a Tujt of Feathers regularly arranged round the External Meatus, which excludes dust, Insects, &c but allows sound to enter readily. In the Owl kind, and several others, chiefly Birds of prey, there is a Membrane-muscular Valve over the pas- sage, which has been compared to the Concha of the Human Ear. The edges of this have a number of slen* der Feathers placed in a circle, which gives a singular appearance to the Animal. The Meatus Externus is little else than a simple hole in the surface of the Scull. It has a liquor secreted in it, which may answer the same purpose as the waxy of the Ear of Mammalia. The Meinlrana Tympani 9 contrary to what happen* in the former class, is convex outwardly, and of an oval form, with the long diameter placed downwards and forwards. The Tympanum is of considerable size, and has with- in it only one Ossiculum Auditus y which is rather of a Cartilaginous consistence, and termed Quadratum from its shape. It is composed of two Branches, which form a kind of Elbow. One is attached along the infe- rior half of the Membrana Tympani, the other goes from the superior part of the former, at the middle of the Membrana Tympani, and divides into slender Crura. PART IL] OF BIRDS. 189 Crura, \vhich unite again in a plate that fills the Fenes- tra Ovalis. There is only one Muscle belonging to the Square Bone. It is situated in the Occiput* behind the Ear, and, penetrating the walls of the Tympanum, is so fix- ed to this small Bone, as to stretch the Membrana Tym- pani. The Eustachian Tube is conical, and entirely Osseous. Jt runs from the Tympanum to the Palate, where it terminates by an opening common to it and its fellow, behind the Internal Nares. Of the two Foramina by w r hich the Tympanum com- municates with the Labyrinth, the Fenestra Rotunda is the larger, contrary to what happens in Mammalia. The Tympanum, in many Birds, particularly in the Owl) communicates with three large Cavities inclosed in the Osseous Plates. These again communicate by an equal number of openings with the Tympanum in the same side, while one extends over the Occiput to its fellow on the other side, and another goes under the Pituitary Gland to the corresponding one on the oppo- site side. In night Birds of prey, these Cavities are very large. In those which seek their prey in the day-time, and in the Gallinacea, they do not communicate on the oppo- site sides of the Head. In Aquatic Birds, they are generally small. In Parroyucts, they have not been dis- covered. The Labyrinth is distinguished by the Semicircular Canals projecting from the base of the Cranium, and in si\ch a manner, that, in many Birds, they are visible M 3 without 190 OF THE EAR [PART II. without any preparation, on account of their not beirfg inclosed by an Os Petrosum, as in Mammalia. The Semicircular Canals are peculiar, by two of them crossing, and communicating with, each other. They are larger in proportion than in Mammalia, and larger in Birds of prey than in others 5 but the Vestible, in Birds, is proportionally small. In place of a Cochlea^ there is a conical Bone, bent a little, and obtuse at its extremity. It passes off from the Vestible, and is divided, as in Mammalia, by a par- tition into two Scalse, which communicate with the Tympanum and Labyrinth as in Man. This, with the other parts of the Labyrinth, receives the Portio Mol- lis, as the Cochlea does in the former class of Animals, OF THE NOSE. 1 HE Organ of Smell is proportionally large, and its acuteness is shewn in Birds of prey, which discover their Food at a considerable distance. The Nostrils vary in situation, size, and form, in different Birds. In some, they are found at the side of the Beak, in others, at its base ; and are placed oppo- site to an opening in the Septum, in consequence of which there is a free communication between the oppo- site L] OF BIRDS. 191 site sides of the Bill. In some individuals, they are so small as to be scarcely perceptible. They have neither moveable Cartilages nor Muscles, but are formed of Laminae covered by the Skin, which is expanded over the Beak. There is no proper Ethmoid Bone in Birds, though they have distinct Ossa Spongiosa, which divide the Cavity of the Nose into different Meatus. The Membrana Pituitaria is plentifully supplied with Vessels, which furnish abundance of Mucus. The Internal Nares commonly open by one chink upon the Palate, which is beset with soft pointed Pa- pillae, turned backward, and furnished with Muscles, V>y which it can be shut at pleasure. The Palatum Molle is wanting. The Foramina Incisiva vary in number, size, and situation, in different Birds. In some, there is but a single opening, which is large; in others, there are raore, but small. In some, it is placed near the point ; in others, at the base of the Bill. The Nose, as in the former class of Animals, is co- piously furnished with Nerves ; the Olfactory come from die fore part of the Anterior Lobe of the Brain, and pass along a Canal, after which they form innumerable Fibrillae, dispersed upon the Membrana Mucosa. In Water Fowls, particularly in the Duck tribe, the Nerves of the Nose, viz, the Olfactory, and a Branch of the Fifth Pair, are uncommonly large, and can be easily traced to the end of their Bills 5 in consequence of which they are enabled to search for their Food in water, mud, &c. M 4 OF 192 OF THE MOUTH, &c. [PART IL OF THE MOUTH, THROAT, AND THEIR APPENDAGES. 1 HE part supplying the place of Teeth, in Birds, itf the Rostrum, or Bill, which is formed of a Horny Sub- stance similar to the Claws and Spurs, and moulded upon the Osseous part of the Jaws. The form and texture of the Bill correspond with the habits and Food of the Animal. In Rapacious Birds, as the Eagle, the Bill is hard and hooked at the end, for seizing and lacerating the prey. It is also of a very firm texture in Birds that bruise hard seeds. In those which live upon softer Food, it is more delicate ; and in such as the Duck kind, which search for their Food in water or mud, it becomes soft and remarkably sen- sible. Many Birds, particularly in the orders Accipitres and Gallinte, have a soft Skin covering the base of the Bill, which gets the name of Cire, (wax), the use of which is not yet ascertained. TONGUE AND SALIVARY GLANDS. All Birds are furnished with a Tongue, the form and structure of which vary much in different Genera and Species. It has Papillae of different forms, some fleshy, soft, and rounded, some Cartilaginous, and placed on its PART IL] OF BIRDS. 195 its root, and also on the Palate, to prevent the Food from escaping after it has entered the Mouth. Some Predaccous and Swimming Birds, and most of the Parrot kind, have a soft Tongue, covered with Pa- pillae, and moistened with Mucus, to enable them to select proper Aliment. In the Parroqitet, it is fleshy, very thick) and rounded before. Nocturnal Birds of Prey have it also fleshy, with soft Papillae turned back- ward. In the Gattinacea, the Tongue is triangular, pointed, smooth, Cartilaginous,, and destitute of Papillae, except- ing at its root; its firmness preventing it from being injured by the hard and pointed substances upon which they live. In the Duck kind, it is fleshy and large, but in seve- ral of these, it is furnished with ranges of Osseous La- minae ; and almost all the kinds have rigid Hairs upon the sides. In the Swan, it is covered with stiff Hairs, Osseous Plates, and fleshy Papilla? ; and some of these substan- ces are directed backwards. In many, as the Toucan, the Tongue is of a Horny consistence, like a piece of Whale-bone ; in the Pie, it is forked, or divided into two parts ; in the Ostrich, of a semilunar form, and remarkably short; in the Pelican, so short, that its ex- istence has been by many denied. The nature of the Tongue is more remarkable in the Wood-cock and Wood-pecker, than many other Animals of this class. In the Wood-cock, the Tongue, and also the Larynx, are placed deep in the Esophagus, and the former can be elevated by Muscles peculiar to it. Th? 19* OF THE MOUTH, &c. [PART II. The Tongue of the Wood-pecker is a sharp Horny substance with barbed edges, and fixed at its root to a Cartilaginous Os Hyoides, consisting of a Body and two pairs of very long Crura. The Body, when in a state of rest, is placed in a fleshy sheath of the Bill. Two of the Crura lie in the Neck, the other two are connected to the former, then proceed completely over the Cranium, running under the Integuments, and are fixed to the Upper Jaw. By means of this apparatus acting like a spring, the Tongue can be thrust some inches out of the Mouth. The Saliva)~y Glands, in Birds, are only met with under the Tongue, where they occupy the place of the Sublingual in Mammalia. They form a mass of small Granulous Bodies, from which a liquor somewhat Vis- cid flows into the Mouth by numerous orifices. In the Gallinacea, they are of considerable size. Two pairs are found in the Turkey, the first lying con- cealed immediately under the Skin, the second on the posterior portion of the first. Their colour is yellow- ish, like the humour they secrete. In the Parroquet, the liquor of these Glands is viscid and grey. In the Wood-pecker, the Salivary Gland extends as far as the Occiput, is of a white colour, and sends out a single Duct, which terminates under the point of the Tongue, discharging a white Liquor into the Mouth. Water Birds in general have but one pair of Glands, which secrete a humour white and viscid, discharged by many orifices ; but in some of the Birds of this order, as the Gull, the Salivary Glands have only a single Duct. QF PAUT II.] OF BIRDS, 195 OF THE HEART AND BLOOD- VESSELS. 1 HE Heart corresponds in its principal parts with that in Mammalia. It has four cavities, which have the same general appearance, and transmit the Blood in the same manner. It is of a conical form, but the cone varies in length or in roundness in different Birds. The si- tuation is nearly the same as in Mammalia, but nearer the anterior part of the Thorax. The Pericardium is covered by the Membrane formed by the Pleura and Peritoneum. The Auricles have no Appendices externally. The Ventricles have Columnae Carnea? in proportion to their thickness and strength. The Valve corresponds with the Tricuspid in Mammalia, is peculiar in being formed of a strong fleshy flap, while the other Valves resemble those in the former class. The Pulmonary Artery is proportionally small, the Lungs occupying less space. The Aorta divides near its origin into three smaller Aortas. The right forms the Posterior or Descending Aorta, the other two form the Subclavian Arteries. The Subclavians give off the Carotids, Vertebrals, Branches to the Neck and Thorax, then divide into Jladial and Ulnar, which are dispersed on the Wings. The OF THE HEART, Sec. [PART II. The Radial is proportionally small, the Ulnar very large, runs along the external edge of the Wing. The Posterior Aorta sends off the Ccdiac to the Sto- mach, Liver, Spleen, Pancreas, and part of the Intes- tines ; then the two Mesenteries. It gives also the Sper- inatics to the Testes and Ovaria, and Anterior Lobes of the Kidneys ; the Intercostals and Lumbars to the con- taining parts of the Body ; continued farther, it fur- nishes Branches to the Kidneys and Pelvis, and at last to the Inferior Extremities. The Veins correspond with those in Mammalia 5 but there are two anterior Cavae, both opening into the upper part of the Auricle. In the larger Birds, as the Ostrich^ Muscular Fibres are seen in the Cavae, particularly in the posterior one. In Diving Birds, the Cava Posterior dilates at the Liver into a sort of Reservoir, somewhat similar to that in the Seal. OF THE ABSORBENT SYSTEM. 1 ILL of late years, Anatomists have been unacquaint- ed with the Absorbents of Birds, chiefly owing to the transparency of the Chyle, and the want of Mesenteric Glands. The Lymphatics are now demonstrated in J3irds gs well as in Man and Quadrupeds, and the struc- ture FART II.] OF BIRDS. 197 ture is also the same as in the former class of Animals ; but this system differs from that of Mammalia, in the Chyle being colourless and transparent, and in there being no visible Lymphatic Glands, neither in the Me- sentery, nor in general any where else, but at the bottom of the Neck ; though in some of the larger Birds a few Glands have been found in other parts of the Body. The Lymphatics of Birds have numerous communi- cations with each other, and form Insulcc, which arc more frequent than in Mammiferous Animals. The Lymphatics of the Inferior Extremities of the Pelvis, and of the Organs of Urine and Generation, and also those of the Chylopoietic and Assistant Chylo- poietic Viscera, join about the Cceliac Artery, and form a Plexus. From this are sent out two Thoracic Ducts, nearly of equal size, which advance under the Lungs, at ach side of the Spine, and go to the inner part of the right and left Jugular Veins, where they terminate a little beyond the union of these Vessels with the Axil- laris. The Thoracic Duct of the Left Side receives a Branch from the Ventriculus Succenturiarus and Esophagus, and likewise the Lymphatics of the corresponding wings. The Absorbents of the Head and Neck accompany the Blood-vessels, and join near the lower part of the Neck, to form a Trunk which penetrates a Lymphatic Gland. From the opposite side of this Gland another Trunk issues, which in the left side terminates in the Thoracic Duct, while in the right, part of it goes to the Thoracic Duct, and part to the Jugular Vein near the Angle it forms with the Axillary. OF ORGANS OF VOICE, &c. [PART IL OF THE ORGANS OF VOICE AND RESPIRATION. 1 HE Organs of Voice and Respiration in Birds differ extremely from those of other Animals. The Larynx is peculiar in being double, or in there being one at each end of the Trachea. The Superior Larynx is situated at the root of the Tongue and top of the Trachea, and is composed of several osseous Pieces, the largest of which is analogous to the Cricoid Cartilage. There are neither Thyroid nor Arytenoid Cartilages, nor Epiglottis, in Birds. The liima Glottidis is a simple Chink or Slit, with Muscular sides, which can merely open and close the passage, having no connection with the formation of Voice. In place of the Epiglottis, there are in many Birds Cartilaginous Papillae upon the edge of the Glottis, to prevent the Aliment from going into the Lungs. In the Ostrich, there is a slight elevation, which some have considered as an Epiglottis. The Trachea is composed of Cartilages or of Bone, 'which form complete rings, and these overlap each other at their edges in such a manner, that the diame- ter of the Tube is not affected by any twisting of the Neck. Its form is commonly cylindrical, sometimes conical, at other times with dilatations and contractions, as in some of the Swimming Birds. The PART IL] OF BIRDS. 199 The Rings of the Trachea have no visible Muscular 1 Fibres, but only Membranes fixing them together; though in larger Birds, as the Cassowary and Ostrich , they are observed to be covered with transverse Muscu- lar Fibres, from which it is presumed they exist in all. The length of the Trachea varies in different Birds with that of the Neck. It sometimes differs in the two sexes of the same Species, especially in Birds of the A- quatic kind, as is observed in the Male Wild Swan, the Crane, and Indian Cock. In these the Trachea makes large convolutions, partly without and partly within the Cavity of the Thorax, before entering the Lungs. Yet there are no such turns in the Trachea of the He- ron, Stork, Bittern, &c. ; these, however, are not pro- perly Diving, but Wading Birds. The use ascribed to this structure is, to retain the in- spired airland thus furnish a sufficient supply of Oxy- gen to the Animal while diving in deep water in search of prey, or flying' in rarified air. These Convolutions have been compared to the wind- ings of a French Horn, and Birds possessing such a Tra- chea are said to be fine singers. But this has been doubted, more especially as such a structure is not found in Singing Birds. The under end of the Trachea, or Inferior Glottis, or Vocal Organ, is formed of tense Membranes, and appears like the reed of a musical pipe. It is contract- ed into a narrow chink, and divided into two openings by a slender slip of Bone, which goes from before back- wards. Sometimes it is formed by the angle made by the two Bronchi. The 200 ORGANS OF VOICE, &c. [PART II. The Vocal Organ is furnished with Muscles from the surrounding parts, and these vary in number in diflev rent Species of Birds. The strength of the Muscles of the Inferior Larynx was found by MR HUNTER to be in proportion to that of the voice. They appeared strongest in the Common Cock, but weaker in the Capon ; and here the Animal has not the power of crowing. The Muscles of the Larynx of the Nightingale were found stronger than any other A,- nimal of the same size. At the Inferior Larynx, the Voice of the Animal is chiefly formed, as may be observed by cutting the Tra- chea across below the Superior Larynx, in a living Bird j or in a dead one, after performing the same ope- ration, blowing in air till it distends the Body, then suddenly forcing it out again ; or by cutting out the under end, with part of the Bronchi, and blowing air from the Pulmonary Extremity. The Inferior Glottis is compared to the reed at the mouth of the wind instruments, as the Clarionet, &c. the Superior Glottis to the holes, and the Trachea to the body of the instrument. The Bronchi are formed of two Tubes, which, like the Trachea, are commonly cylindrical, but sometimes Lave dilatations and contractions, and are composed of Cartilaginous or Osseous Arches, the curves varying occasionally by the action of the Muscles. The Bronchi proceed in angles more or less acute, but are never subdivided till they enter the Lungs, after which they lay aside their Cartilaginous struc- ture, and become entirely Membranous ; but the FART II.] OF BIROS. 201 Swan and Cassowary are observed to be exceptions to this last circumstance^ In the Males of the Genus Anas, and Mergus, or Duck tribe, the Bronchi form Osseous Cavities, which give particular tones to their voice. The Lungs of Birds differ from those of the Animals of the former class in several circumstances. They oc- cupy but a small part of what, in Quadrupeds, forms the Thorax ; they are firmer in their texture, and not divided into Lobes, though separated above by the Ribs, the interstices of which they occupy. They ad- here, at their upper part, to the inner side of the Tho- rax through their whole length ; while below they have a flattened appearance, where they lie over the Air- Cells. The Pleura here is but a partial Membrane, adhering only to the inferior surface of the Lungs ; of course, they may be considered as lying on the outside of the Cavity of the Chest. They consist of two red spongy masses, which have less Cellular Substance than in Mammalia, but the Cells are much larger in proportion. The Branch- es do not all end in the Cells of the Lungs ; many ter- minate on their surface, the Pleura being here Cribri- form, and allowing air to pass by considerable orifices into Cells, which conduct it to the whole Body. The Air Vesicles are of great size, but they vary much in this, as well as in their form, in different Birds, and in different parts of the same Bird. They cover and inclose all the Viscera of the Thorax and Abdomen, and communicate by wide openings with each other. Most of the Cells are subdivided, especially in large VOL. IV, N Birds, 202 ORGANS OF VOICE, &c. [PART II. Birds, by incomplete transparent partitions, which al- low the air to pass from one part of the Cell to another, and prevent them from being over-distended. In Adult Birds, the Air- Cells not only communicate with each other by considerable apertures, but also with the Cavities in the middle of the large Bones, of whatever form. In many, they extend to the Axillae, and under the Pectoral Muscles, and even along the Shoulder under the Skin of the Wing and lateral parts of the Neck. This is found particularly to be the case in high-flying Birds, in which, also, they are remarkably large. They are extremely thin in their texture, but so dense, as to prevent the air from escaping, except by the apertures which conduct it through the Body. In large Birds, the Cells are furnished with Fasciculi of Muscular Fibres, considered as a substitute for the Diaphragm. These serve to expel the air received in inspiration, and send it back by the Lungs and Tra- chea, in which they are assisted by the Muscles on the Thorax, Abdomen, &c. The distension of these Cells serves to render the A- nimal lighter in flying, so as to buoy it up in the air, and diminish the necessity of inspiring frequently in a long or rapid flight; and also in singing or swimming ; and in large Birds, as the Ostrich and Cassowary, in running. They answer, besides, as a kind of secondary Lungs to the Blood, and are useful in the expulsion of the Faeces, Urine, and contents of the Genital Organs. They are also concerned in the respiration, the Lungs i . possessing PAUT IL] OF BIRDS. 203 possessing little mobility on account of their attachment above to the Thorax, which has little motion where they are fixed to it. The rest of the Thorax, however, admits of considerable dilatation, so as to determine the air to the Cells ; and the double articulation of the Ribs likewise favours this. Inspiration, in Birds, is owing to a dilatation of the Air-Cells from Muscles acting upon the Thorax ; or, upon the Lungs, as is observed in such large Birds as the Ostrich and Cassowary. Expiration is produced by a relaxation of the Muscles employed in Inspiration ; by the action of Muscles si- tuated over the Air-Cells ; and more particularly about the Abdomen, bringing the posterior part of the Ster- num nearer the Vertebrse; and, according to some Authors, by the power of the Lungs themselves, as is observed in the larger Birds. The strength of the voice depends upon the propor- tional strength of the Aerial Cavities. The facility of modulating it, depends upon the mobility of the Muscles which contract the Lungs. The difference of voice in different Birds depends upon the proportional length, form, consistence, and mobility of the Rings of the Tra- chea. The cause of the loss of voice in some Birds, as the Quail, Cuckoo, &c. at certain seasons, is not under- stood. N2 OP 201. OF THE ALIMENTARY CANAL [PART II. OF THE ALIMENTARY CANAL. 1 HE Viscera of the Abdomen, in Birds, are contained in the same common Cavity with those of the Thorax, and, as in the former class, are covered by the Perito- neum, which is here so confounded with the Pleura, that the two may be considered as one Membrane. The Animals of this class being divided into Grant- vorous and Carnivorous, the Bowels of the two kinds are considerably different from each other. The upper part of the Esophagus agrees in its nature in Birds in general ; but in a few, there are peculiari- ties. In the Pelican, there is a remarkable dilatation or Pouch in the Fauces, capable of holding some quarts, and serving as a reservoir of the Food, which common- Jy consists of Fishes. There is also, in the Male Bustard, a Throat Sac under the Skin of the Neck, which has an opening of considerable size under the Tongue, but the use is un- known. Granworous Birds. The Esophagus is generally a little inclined to the right side of the Trachea, and terminates at the bottom, of the Neck in a large Sac, the Ingluvies or Crop, which is of the same structure with the Esophagus, but thinner. The PAUT II.] OF BIRDS. 20.1 The Crop, in the Gallinaceous Birds, is of a globu- lar form, and placed at the fore part of the Chest. The Esophagus opens at its upper or fore part, begins again about its middle, the Crop forming a sort of Cid-de-Sac between these two orifices. Upon the inner side of the Crop are numerous Glands, with very distinct orifices, in large Birds, which throw out a liquor to assist in the solution of the Food. In many, the Glands are in irregular rows. lu the Pigeon, &c. which nourish the young from the Crop, the Glands swell remarkably at that time. The Pigeon has a spherical Bag on each side of the Esophagus, and these, in the Poulting Pigeon, are fill- ed with air, so as to give the appearance constantly ob- served. The Crop is peculiar to Granivorous Birds, but IP wanting in the Ostrich, To the Crop succeeds another Cavity, in the shape of a Funnel, called Ventriculus Succenturiatus, Infundi- bulum, or Second Stomach. This is situated in the Ab- domen, and is commonly smaller than the former. It is more general among Birds than the Crop, and va- ries much in size in the different Species. It has a covering from i*he Peritoneum, and is generally thicker than the Esophagus, owing to its numerous Glands, from which a fluid is discharged. In the Ostrich, this Stomach, from its size and form, lias the appearance of a Crop. The Mucous Glands here are about the size of Garden- Peas, and have ori- fices uacommonly distinct. It dilates into a Bag ca~ N 3 206 OF THE ALIMENTARY CANAL. [PART II. pable of containing several pints of water, and is much larger than the proper Stomach into which it opens. The Infundibulum, in Birds, ends in the Ventriculus. Callosus, Gizzard, or Third Stomach, which, in Galli- naceous Birds, is much larger than the Infundibulum ; but in others, it is the reverse In the Pie, the Third Stomach is only about half the size of the Second, and in the Ostrich, several times less. It is generally situated in the upper part of the Abdomen, close to the Spine, and resting upon the Intestines ; though, in some few Birds, it is covered by these. It is commonly of a globular figure, and a little com- pressed, and is composed of four Muscles, remarkable for their great thickness and strength. Two of these are situated laterally, and have Fibres running in a ra- diated manner about two Tendons placed at the sides of this Organ. The other two Muscles are much smaller than the former, and are situated at the extre- mities of the Stomach. The Gizzard is covered externally with a'Tendinous Expansion, and lined within by a thick, strong, cal- lous Coat, considered by some as a continuation of the Cuticle. In the Chick, it is only a thin Pellicle, and becomes thick from attrition. This Layer forms irregularities in the inner side, which are adapted to each other on the opposite sur- faces. The Cavity of this Stomach is proportionally small, when compared with its external surface, and its two orifices are remarkably near each other. Its thickness is supposed to compensate for the want of Teeth. So great is the strength of this Organ, that piece* PART II.] OF BIRDS. 207 pieces of Money, and even Pebbles of the hardest kind, swallowed by a common Fowl, have, in a few days, lost considerably of their weight. Each of the small Muscles at the extremities of the Gizzard, contains a kind of receptacle for the stones necessarily swallowed, while the digested portion of the Food passes to the Intestines. The Parroquet, and. some other Birds, are observed to chew the cud like Ruminant Quadrupeds. JFbao/s, Geese, -&c. having hard and callous Stomachs, are termed Spurious Humiliating Birds. Carnivorous Birds. The Esophagus here is of great size, for receiving the large substances these Animals swallow, and for discharging by the Mouth, Feathers and other substan- ces, that cannot readily be digested. In the Hawk kind, the Esophagus is so wide, as to be considered by some a kind of Crop ; and so large is this passage in some Fish-eaters, that whole Animals are contained in it till the Stomach can receive them. The structure of the Stomach of these Birds differs much from that of the plurality of Stomachs in the former kinds, being merely a Musculo-membranous Sac. The Food, too, is here more easily digested. But there are many intermediate links in the diversified structure of Stomachs in the Animals of this class. Most Piscivorous Birds want the Crop; when this is the case, the Infundibtilum is larger, as if to supply its place. N 1 The 208 OF THE ALIMENTARY CANAL [PART IL The Pylorus, in Birds, has no Sphincter. The Intes- tinal Canal is much shorter than in Mammalia. It varies from twice to five times the length of the Animal. In the Ostrich, on the contrary, it is found to be between twenty and thirty times the length. The Canal is also shorter and narrower in Carnivorous Birds than in those living on vegetable Food, yet many Fish-eaters have it equally extensive, In all Birds, there is a distinction into small and great Intestines, though, to external appearance, the difference is very inconsiderable. The small Intestines are commonly longer than the great, as in Mammalia ; but sometimes shorter, as in the Ostrich. The situation, form, and structure of the Intestines, is nearly the same in the greater number of Birds. The Duodenum begins near the termination of the Eso- phagus, but there is a prominence, in some, as the com- mon Fowl, between the two openings, which may prevent the Food from escaping till properly digested. The Gut hangs loose, in the common Fowl, towards the right side of the Abdomen, the rest of the small In- testines making turns, and uniting themselves to each other. They are destitute of Valvulse in Birds in gene- ral ; but in many, there is a Villous appearance in them. There are commonly two Intestina Cccca in Birds, a few of the Aquatic kind excepted, which have only one. The Caeca are inserted at the sides of the termination of the Ilium. They are generally smaller at their base, and enlarge towards their shut extremities. They lie parallel to the small Chits, and contain the same kind of with them. In Granivorous and Omnivorous Birds, PART II.] OF BIRDS. 209 Birds, they are commonly long, and of considerable diameter. In nocturnal Birds of prey, they are com- monly very large ; but in the diurnal Birds of prey, they are wanting, or of inconsiderable size. There are many exceptions to the above rules. In the Ostrich, the Caeca are remarkable for their spiral Valves. From the end of the Ilium, and also from the Caeca, when present, the Colon is sent off, which is propor- tionally short, and differs from that in many of the for- mer class, in not being formed into Cells. In the Ostrich, however, the Colon, as it advances, becomes tacked up into Cells, and gradually increases in diameter, contrary to what happens in other Animals. The Intestines are fixed to the Body by the Mesen- tery, which arises from the Spine opposite the Anterior Mesenteric Artery. It is of considerable breadth where it is attached to the small Intestine ; but what belongs to the Colon is narrow, this Gut being more firmly fixed than the rest. The Rectum, previous to its ending in the Anus, forms a dilatation termed Cloaca, which is suspended under the Os Coccygis, and receives the terminations of the Ureters, the ends of the Vasa Deferentia, and Penis, where it exists ; the opening of the Oviduct in the Female, and the orifices from the Bag termed Bursa FABRICII. The Cloaca varies in form in different Species, but has more or less of an oval appearance. It serves as a reservoir of Urine and Faeces in both sexes. It is moved by various Muscles which arise from the Bones in the neighbourhood. The 210 OF THE ALIMENTARY CANAL [PART II. TheBursa FABRICII is situated at the upper and back part of the Cloaca, into which it opens in both sexes. In some of the large Birds, as the Goose, it is fully an inch in length, and is lined with Mucous Glands inter- nally. It is largest in young Birds ; in old ones, it is quite contracted. It is constantly found empty, and its use is unknown. The Omentum is wanting in Birds, unless a lump of Fat which covers the Intestines in some Aquatic Fowls, be considered as such. In the Ostrich, there is an O- jnentum with a large quantity of Fat. OF THE ASSISTANT CHYLOPOIETIC VISCERA. LIVER. 1 HE Liver is generally larger in proportion, in this class of Animals, than in the former, especially in Birds of prey, and is observed to be larger in Domesticated than Wild Animals of the same Species. The figure is more uniform in Birds. There are commonly two Lobes of equal size, which occupy both sides of the Abdomen ; but in some, the left is larger than the right, or in others, is divided into two Lobules. It is supported by the surrounding Viscera, and is fixed by Processes from the PART II.] OF BIRDS. 2il the Peritoneum. The colour is a reddish brown, but the tint varying in different Species. The Gall-bladder is placed between the two Lobes of the Liver, and is sometimes closely attached, at other times is loose and pendulous. It is in some oval , in others, of a spherical figure, and, as in the former class of Animals, has its Fundus placed undermost. In many Species of Birds, the Gall-bladder is want- ing, as in the Pigeon, Parrot, and Ostrich. The Hepatic Duct, in Birds in general, opens sepa- rately from the Cystic, into the Duodenum. There is no communication between the two Ducts; of course, the Bile found in the Gall-bladder does not get there by regurgitation, as it commonly does in Mammalia, but directly from the Biliary Vessels in the Liver by means of Plepato-cystic Ducts, which open either into the Fundus or the Cervix of the Gall-bladder. These, besides supplying it with Bile, assist in connecting it to the Liver. In some Birds, as the Duck, the Hepatic and Cystic Canals unite into a common Tube -, and in the Parro- quet, there are two Hepatic Ducts which open sepa- rately into the Duodenum. SPLEEN. There is generally one Spleen only, and this varies much in form, being round, oval, reniform, &c. in dif- ferent Birds. It is situated between the Left Lobe of the Liver and the Stomach, and is fixed in its place by plies 212 OF THE LIVER, &c. [PART II. plies of the Mesentery, as in the former class It is destitute of an Excretory Duct, but, as in Mammalia, it sends its Blood to the Liver, by which part of the Bile is secreted from it. PANCREAS. The Pancreas of Birds is situated between the Folds of the Duodenum, and is generally of considerable size. It varies a good deal in its form, but is commonly long and straight, and is almost always divided into two parts, and in some of the class there is a double Pancreas. Its Structure is the same as in the former class, viz. a Gland of the Conglomerate kind. It commonly sends one, two, or three Ducts, which are more visible than in other Animals ; and these terminate distinct from the Biliary Vessels, with few exceptions. Of the Insertion of the Biliary and Pancreatic Ducts there is great variety ; but from many comparisons it appears, that the Pancreatic Duct opens first into the Intestine, that the Hepatic is inserted a little farther on, and that at a little distance farther is the termination of the Ductus Cysticus. ! KIDNEYS. The Kidneys^ which are proportionally large in this class, are placed in the Cavities of the Ossa Innominata, at the sides of the Lumbar Vertebras, with a few excep- tions. They form a double row of irregular Lobes, con- joined together, though the first are generally separated x from PART II.] OF BIRDS. from the rest, and are the largest. On each side, this first Lobe receives an Artery from the Aorta, the others from the Femoral Artery. They return their Blood to the Femoral Vein and Vena Cava. Each Kidney sends out an Ureter, which terminates in the upper part of the common Cloaca, but not in the Penis. The Urinary Bladder is absent in the whole class. The Urine generally mixes with the Faeces, and in the common Fowl, has a chalky appearance. In the Ostrich and Cassowary, the Cloaca serves as a Bladder, and they are the only Animals of the class which are observed to pass Urine. RENAL GLAND. The Renal Gland in Birds appears proportionally small. It is situated at the under and fore part of the Kidney, is generally of an Orange colour, and uniform in its substance. OF THE MALE ORGANS OF GENE- RATION. 1 HE Testes and Vasa Deferentia are found in all the different Animals of this class. The Testes are situated in the Abdomen, close to the sides of the Spine, behind the 21* OF THE MALE ORGANS [PART II. the Lungs, and below the fore part of the Kidneys. They are commonly of an oval, but sometimes of a roundish form, and vary much in size in the different Genera and Species. They increase considerably in bulk in the seasons of their sexual intercourse, and are proportionally larger than in Mammalia. They are co- vered, and fixed in the Body, by a Process of the Pe- ritoneum, and consist of a Congeries of delicate Semi- nal Ducts, which are less distinct than in the former class of Animals. The Epididymis here is closely connected to the Tes- tes, and sends out the Vas Deferens, which runs in a flexuous manner near the corresponding Ureter. It becomes larger by degrees, and terminates in the Cloa- ca, distinct from the Ureter ; but frequently before its termination, it dilates into an oval Sac, that is consi- dered by some Authors as supplying the place of a Ve- sicula Seminalis. The Duct is commonly full of an opaque white fluid, and its outer extremity, in some Birds, as the Duck, is situated between two Erector Muscles, which, by compression, can discharge its con- tents. The Prostate Gland, in this class of Animals, is wanting. In general, each Vas Deferens terminates in a Penis peculiar to itself, which is a mere Papilla, placed at the side of the common Cloaca, and pointing outwards, as in the Cock, Turkey, Pigeon, and large Birds of prey. Some, as the DucJc, Swan, &c. have a single Penis, of considerable length, which, in a relaxed state, is a simple Tube, coiled up, and concealed in a Pouch, opening PART II.] OF BIRDS. opening into the Cloaca. In the erect state, it is some inches in length, but this varies according to the size of the Animal. Some Muscles are placed at its root, for giving it the necessary degree of erection, its own elasticity after- wards relaxing it. In the Ostrich, HocJco, and Cassowary, the Penis is similar to that in the Drake ; but, in place of a Tube, there is only a Groove for conducting the Semen from the Cloaca. No rule is yet found with respect to the Birds that have a double or a single Penis. In the Ornithorrynchus Paradoxus, there are two Pe- nises, as in Birds. OF THE FEMALE ORGANS OF GE- NERATION. THE Female Organs consist of the Ovarium, or Ras- mus Vitellorum, Oviduct , and the Cloaca. The Ovi- duct is divided into Infundibulum, Oviduct strictly so called, Uterus, and Vagina. The structure of these parts is so uniform in Birds in general, that the common Fowl may suffice as an example. The Racemus Vitellorum corresponds with v the Ova- rium in Mammalia, is situated under the Liver, be- tween the anterior portions of the Kidneys, and is in- closed 216 OF THE FEMALE ORGANS [PART II. closed by a Process of the Peritoneum, which attaches it to the Spine. It consists of a cluster of Ova, resem- bling a bunch of grapes, but varying in size, from the full-grown yoke to that of a grain of mustard-seed. The largest are yellow, the smallest white ; and in a Hen beginning for the first time to lay, the number is about 500. The Ovaria have Blood-vessels similar to those of Mammalia, which also assist in fixing them in their place. The largest of the Yolks are always found at the outer side. Each is inclosed in a Calyx, or Membrane, and supported on a Pedicle^ or Foot-stalk, which is fixed to the Ovarium. When the Yolk is ripe, it bursts the Membrane, and is then received by the Infundibulum, which conveys it to the Oviduct. The Infundibulum has a plaited or folded margin, like the Fimbrias of the FALLOPIAN Tube, and is connected behind by a round Ligament. The Tube is at first straight, but afterwards so convoluted, as frequently to exceed the length of the Bird, and gradually increases in thickness and strength, till it reaches the Cloaca. Externally, it is covered by the Peritoneum, within which are some Muscular Fibres. The inner side is formed by a Membrane covered with Follicles, which secrete the white of the Egg. It has a number of broad longitudinal folds, and is connected to the Spine by a kind of Mesentery. The Oviduct terminates, and deposites the Egg, in the Uterus, which is full of wrinkles internally, and may be considered as merely a dilated part of the Ovi- duct. PART II.] OF BIRDS. 217 duct. In the Uterus, the Egg receives first its form, and then its shell. The Vagina^ in the common Fowl, is about an inch and a half in length. From this the Egg is discharged into the Cloaca^ by the Muscular power of the Uterus, and action of the surrounding parts. The termination of the Vagina is at the left side of the Cloaca, which receives also the end of the Rectum and the two U- reters. Behind, and above the Cloaca, is the Bursa FAB, r .icn 9 so called from the Author who was of opinion, that the Organ receives and retains the Semen of the Cock ; it exists, however, also in the Hen. Behind the Ossa Pubis, is the external opening of the Cloaca, that is larger in the Hen than in the Cock. The Anterior Labium, which is the smaller of the two, is covered by the posterior one, termed Vela- brum. Structure of the Egg. The Shell is lined by a white and very dense substance, the Membrana Albuminis, that is destitute of Blood-vessels. Ths two Laminae of which -this Membrane is composed, are separated at the large end, and leave between them a cavity filled with Atmospheric Air, the Folliculus Aeiis, which is larger in an Egg kept for some time than in one recent- ly laid. The Membrana Albuminis incloses the Glaire of the Egg, which is separated into an outer and inner por- tion ; the inner, as well as the outer, is surrounded by 3 Membrane, delicate and very dense, yet allowing the Glaire to transpire when the Egg is long kept, especially VOL. IV. O * in OF THE FEMALE ORGANS in a warm atmosphere. The outer Glaire, which is more fluid and transparent than the inner, can be readi- ly separated from it after being boiled, or otherwise hardened into a coagulum. The inner Glaire incloses the Yolk) which is contain- ed in a Membrane termed Yolk-bag. The Yolk is pro- portionally heavier than the Glaire, and has attached to the Membrane which covers it, two white Bodies like coagulated Glaire, termed Clialaza or Grandines. The other extremities of these Bodies, considerably expand- ed, penetrate and float in the Albumen. The Chalazae form two ends of an axis, being placed at the opposite sides of the Yolk, but at a little dis- tance from its centre, in consequence of which the large portion preponderates. On the surface of the Yolk-bag is the Cicatricula or Macula, termed also the Tread of the Cocky which is surrounded by concentric circles, the Halones or Cir- cuit, the use of which, and of the Chalazae, is not yet fully ascertained. The Cicatricula, being placed upon, the smaller portion of the sphere of the Yolk, is found uppermost in whatever position the Egg happens to be placed. Changes produced up6n the Egg in time of Hatching. This process is effected by the assistance of Atmo- spheric Air, and a certain degree of heat, both of which circumstances are produced by Incubation, or by the Egg being kept for a sufficient length of time, in air heated to an equal degree with that produced by the Animal. But varnishing an Egg all over stops the pro- gress of Incubation, by obstructing the access of the ai?, though FART II.] OF BIRDS. though covering the large end with a varnish has not that effect. The influence of the Male Semen is supposed to af- fect the Ovum either in the Uterus, or passes through the Tube, to fecundate the Ova in the Yolk-bag, but in what manner is not yet understood. During Incubation, the Folliculus Aeris is gradually expanded, air being now secreted from surrounding Vessels, which prevents the Chick from being too much moved about in the Shell. The Albumen becomes thinner and more turbid, part of it escapes through the Shell by evaporation, the rest of it is by degrees con^ sinned by the Chick, till at last there remains but a white Cretaceous Substance at the small end of the Shell. The white of a fecundated Egg is somewhat coagu- lable, and perfectly fresh, during the whole period of hatching. The Yolk becomes paler and more fluid for some time, on account of being mixed with the white. Its Membranes become firmer and stronger. By de- grees it becomes depressed in the middle, and forms an Arch about the Chick. It remains quite free from cor- ruption, is coagulable all the time of Incubation, and* during this period, is entirely taken into the Abdomen. The Chalazse degenerate into a chalky-like substance towards the end of Incubation, The Cicatricula, by enlarging, forms the Amnios, which contains the Colli- quamentuni) or liquor in which the Chick is immersed at the earlier part of Incubation, but which is consumed by the end of it. By degrees, Umbilical Vessels are formed upon the O 2 Amnios, OF THE FEMALE ORGANS [PART II. Amnios, Yolk, and Membranes of the Albumen, in which last substance the greater part of the Branches are expanded. The lining of the Shell is now cover- ed with Blood-vessels, expanded upon a Membrane which forms the Chorion. Near the end of Incuba- tion, the Umbilical Vessels begin to shrivel, and, at the exclusion of the Chick, are quite diminutive. Production of the Chick. At the end of the first day, a small white spot, the Nidus Pulli, seu Colliquamentum^ is discerned near the Cicatricula. On the second day, the Chick is observed in the form of a Gelatinous Filament, and the Cicatricula soon afterwards vanishes. At the end of the second day, Blood-vessels appear upon the sur- face of the Yolk, and these soon become connected to the Chick. The Vascular part is termed Uigur a Veno- sa, or Area Vasculosa. The Arteries arise from the Mesenteric ; the principal Vein goes to the Porta. Be- sides the Blood-vessels, a Canal is formed in the course of Incubation, which joins the Membrane of the Yolk to the Intestinum Ilium of the Chick, under the name of Ductus Vitello-intcstinalis. Third day, the Punctum Saliens, or Hearty appears, and is distinguished by its motion. The Spine is seen in a curved state, with pro- minences, which are the Brain and Eyes, the latter of which are remarkable for their great proportional size. Fourth day, the Abdominal Viscera appear, after which the Extremities sprout out. A Vascular Membrane, the Chorion) or Membrana Umlilicalis, begins to form about the Navel, which, increasing by degrees, lines almost the whole inner surface of the Membrana Albu- minis during the latter half of the period of Incuba- tion. PART II.] OF BIRDS. 221 tion. The Chorion consists of innumerable Arteries and Veins ; die latter are distinguished from the former by being filled with pure red Blood, while the Arte- ries have a livid appearance, on account of transmit- ting carbonated Blood from the Animal. The Chorion is therefore considered as supplying the office of Respi- ratory Organs, while the Chick lies in the Amnios, and is prevented from breathing. Fifth day, the Lungs are perceived. Sixth, there is voluntary motion. Ninth, Ossification commences ; traces of yellow Ves- sels on the Yolk-bag, Vasa Vitelli> and Lutea, begin to appear. These afterwards expand in the substance of the Yolk, and, by degrees, carry it into the Veins of the Yolk-bag for the nourishment of the Chick. o Fourteenth, the Feathers are discerned. Nineteenth, the Animal has the power of using its Vocal Organs, and, some time before its exclusion, may frequently be heard making the same kind of sound that Chickens make after they are hatched ; and this in consequence of breaking with the Beak the Air-bag placed at the great end of the Shell. Twenty-first, it makes its ap- pearance, sometimes by bursting the Shell irregularly, at other times perforating the larger end with its Beak. While the Chick lies in the Shell, it is coiled up, with its Neck bent forwards, the Head covered by the "Wing, and the Yolk between its Legs. Directly after leaving the Shell, the remains of the Yolk and its Bag are observed in the Abdomen ; the former is taken into the Intestines, and serves for nourishment till the Animal acquires strength enough for another kind of Food. O3 PART PART III. OF REPTILES. OF THE BONES. 1 HE general structure of the Skeleton of Reptiles va- ries much in the different orders of the class. The Cranium, for the most part, is large in proportion to the size of the Brain, though small when compared with the bulk of the Head. In the Turtle, the apparent magnitude of the Head is owinn to the Accessory Bones, between which and tLe Cranium there is a large space occupied by .Muscles and Glands, and by the Organs of Vision. The Cranium is joined to the Vertebrae of the Neck by a single Occi- pital Condyle. The Lower Jaiv is composed of five pieces, one in the middle, and two at each side ; and is articulated somewhat after the manner of the articulation in Birds. It has no Condyle, but a hollow articular surface, which is joined to an eminence of the Temporal Bone $ a fetructure the reverse of that in Mammalia, In all other Reptiles, there is nearly the same kind of Articulation as in the Turtle. There are no Teeth in the Turtle kind, in place of which their Jaws are co- vered III,] OF REPTILES. 223 vered with a Horny substance, similar in structure and connection to the Hoof on the Foot of the Horse ; and so strong, as to be capable of breaking substances of great hardness. The Os Hyoidcs varies much in this and the other orders of the class, though in general it approaches, in its appearance, to that of Birds. Seven Vertebra enter into the composition of the Neck. The Trunk is formed of two great portions, the Dorsal and Abdominal Shells. The Dorsal, Lum- bar, and Sacral Vertebrae, are all united into one piece, but the Vertebras of the Tail are free and moveable. The Dorsal Shell consists of a great number of Os- seous Plates, regular in their position, and approaching to a quadrangular form. '1 hey are connected to each other by Suture, and joined to the Abdominal Shell by a thick and very tough Skin. The Abdominal Shell, like the Dorsal, is also com- posed of many Plates joined together by Suture, and forming a kind of Sternum, which covers almost the whole inferior part of the Body of the Animal. The Os Innominatum possesses the same number of pieces with that in Mammalia; but the Os Pubis is the largest, and the Os Ilium the smallest of the three. The Ribs are eight in number, but are all anchylpsed with the Vertebrae of the Back and the Dorsal Shell. They terminate in a border, which surrounds the Shell, and are united to it by Suture. The Scapula has a singular situation before the Shell of the Abdomen. The Clavicle consists of two pieces joined in an acute angle. There is also a Pork-like Bone in these Animals, to which, and to the Clavicle O4 and OF THE BONES [PART III. and Scapula, the Os Humeri is fixed as in Birds. This and the other four-footed Reptiles have two Bones in the Fore-Arm, though the division into two is not very distinct. In the Tortoise, the Feet are proportionally small, in consequence of which the Animal is observed to be slow in its motions. There are three Ranges of Bones in the Carpus, the pieces varying in number in the different ranges. The Phalanges of the Fingers or Toes are nearly as in Mam- malia ; but in the Sea Tortoise, the different pieces are flat, being formed into a kind of Fins. The Frog and Toad have no motion in the Upper Jaw, and they are destitute of real Teeth, though they have pointed Bodies serving as a substitute, and placed in the Palate ; the Frog has them also in the Upper Jaw. The Head is joined by two Condyles to the Spine, which is short, and terminates behind by a single Bone, articulated with the Os Innominatum. The Dorsal Vertebra? have broad Transverse Pro- cesses, that may somewhat supply the place of Ribs, which are wanting here. The Os Sacrum consists of one long Bone. There is no Os Coccygis in these animals. The Scapula is joined to the Sternum by double Cla- vicles, or there is a Clavicle and Fork-like Bone on each side. The Fore- Arm and Leg consist of a single Bone, divided at its extremities into two portions. The Car- pus is formed of three ranges. The Frog has one Bone to the Thumb, two to the second and third Fingers, three to the fourth and fifth Fingers. In the Lizard tribe, the Cranium, or at least the ca- vity for the Brain, is uncommonly small. In a Croco- dile FART III.] OF REPTILES. 225 dlle that measures between twice and thrice the length of the Human Body, the cavity of the Cranium is only about three inches long, and the third part of that in breadth ; and in the Cameleon, it is not found larger than a common pea. The Crocodile has a single Parietal Bone, but both in that Animal and the Lizard^ numerous pieces enter into the composition of the Lower Jaw, which is pro- portionally larger in the former Animal than in any other creature. The two Intermaxillary Bones form the end of the Maxilla Superior, and surround the Nos- trils. The Under Jaw corresponds with that of other Animals of the class, in having an Articular Cavity for receiving a Condyle of the Temporal Bone. An uncommon structure is observed in the Teeth, which consist of two Sets, one contained within the other, which is found to facilitate their change. The Head is joined to the Atlas by a single Condyle. Lizards have perfect Ribs, of which there are twelve pairs in the Crocodile, but the Sternum is in a great measure Cartilaginous. This Animal is remarkable in having a double Sternum, one belonging to the Thorax, and another extending along the Abdomen as far as the Pubes. There are Seven Cervical Vertebras here, but the five last are found to be so encased, that the Animal cannot turn the Neck laterally. The Sacral Vertebrre are all joined into one piece in all the Animals of this order. The Bones of the Extremities have nothing very remarkable. In the Salamander, the Sternum, Clavicle, and Sca- pula, are in one piece, which receives the Head of the Os Humeri. In this class, the Fibula, as well as the Tibia, ^26 OF THE BONES [PART III. Tibia, is in general articulated directly with the Os Fe- inoris ; and in all, the Astragalus is joined to the Tibia, und the Os Calcis to the Fibula, Of the Serpents, one set move the under Jaw only, another set, viz. the Vipers and Venomous Serpents, move both Jaws. The Lower Jaw is articulated by a Glenoid Cavity, which corresponds with a Condyle of the Tem- poral Bone at the bottom of the Cranium. Serpents, whether innoxious or poisonous, are divided according to the nature of their Teeth. The former have both Jaws beset with small Teeth in two rows, with an interval between them. In the Poisonous Species,, the outer row in the upper Jaw is wanting, but their place is supplied by long hollow Tusks f which are con- nected with the Bag containing the poison, and serving as Excretory Ducts to convey it from the Glands at their roots, into the wound the Animal inflicts. The Tusks lie concealed in the Jaw, but can be darted out at the will of the Animal. In all the poisonous Ser- yents, the Upper Jaw is moveable on the Cranium. This allows them to open the Mouth widely? by which they are enabled occasionally to swallow an Animal en- tire, the diameter of which sometimes surpasses that of their own Body. Serpents are remarkable for the number of their Ver- telrce, which form almost the whole Skeleton. They vary in number from about 30 to upwards of 250, and are nearly of the same form from the Head to the Tail. They are connected by Ball and Socket. This articulation, however, is of such a nature as to allow free motion laterally, but little in a vertical direction. The PART III.] OF REPTILES. 227 The last Vertebra of the Tail supports the Rattle. The Sternum is wanting, and, there being no Limbs, the. Bones of the Extremities of course are absent. OF THE MUSCLES. 1 HE two principal divisions of the Animals of this class, viz. those with, and those without Feet, have a remarkable difference in the form and number of their Muscles. In the former, viz. the Turtle, Frog, &c. where the Trunk of the Body possesses proportionally a small degree of mobility, a number of Muscles are wanting, though the others are strong. In the Animals of this class without Feet, namely, the Serpents, the Muscles are slender, but extremely numerous, on ac- count of the number of the Vertebrae, and the want of Anterior and Posterior Extremities. In the Turtle, the Spine possesses no motion but in the parts belonging to the Neck and Tail. The Back and Loins, being ossified together, have no Muscles. The Diaphragm, and also the Muscles of the Abdo- men, are wanting; but the other Muscles are remark- ably strong. The Neck possesses chiefly Muscles for elongation and retraction ; the Neck being bent, when retracted into the Shell, somewhat like a Z, though it can be moved in various directions when it protrudes frorn the Shell. .The Muscles for these motions are nu- merous, 228 OF THE MUSCLES [PART III. merous. Some pass from the under and fore part of the Back Shell to the Vertebrae of the Neck, and others from one set of Vertebrae to another. One Muscle is peculiar to this Animal, which arises from the first Dorsal Vertebra, and is fixed to the sixth and seventh Cervical Vertebrae. It begins the extension of the Neck, when the Head is concealed in the Shell. About half a dozen pairs of Muscles lie on the back part of the Neck, chiefly for raising the Head, or pull- ing it laterally. A few Muscles also appear below, par- ticularly one supplying the place of the Sterno-mastoi- deus, for bending the Head, and producing a slight elevation of the Shoulder. The Muscles of the Shoulder are only three in num- ber, and are analogous to the Trapezius, Levator Sca- pula?, and Subclavius. The Muscles of the Humerus are more numerous than in other Animals, to give the necessary motions in swimming. They arise from the Bones of the Shoulder, and from the inner side of the Dorsal and Abdominal Shells. The Pectoralis Major is composed of several portions. There are something like two Deltoids. The other Muscles are analogous to the Latissimus Dorsi, Levator Brachii, Teres Major, and Biceps. The Muscles of the Fore-arm, and remaining part of the Anterior Extremity, are in a great measure A- poneurotic, the Member being in the form of a Fin, as in the Cetacea. This is particularly the case in the Sea Tortoise, where the Muscles are Aponeurotic Bands, which strengthen the Articulations. Muscles of the Posterior Extremity. There is a Muscle, PART III.] OF REPTILES. 229 Muscle, analogous to the Quadratus Lumborum, lying under the Dorsal Shell, and moving the Os Ilium ; and another, supplying the place of a Rectus Abdominis, arising from the posterior extremity of the Abdominal Shell, and fixed to the Pubes. Of the Muscles of the Thigh, there are different Adductors. A Muscle from the Pubes is fixed to the small Trochanter, and holds the place of the Iliacus and Psoas. One Muscle arises from the Spine, and two from the Pubes, which corre- spond to the Glutei. A Muscle analogous to the Ob- turator Internus arises from the Ilium, and is fixed to the great Trochanter. The Muscles of the Leg are analogous to the Semi-membranosus, Semi-tendinosus, and Sartorius. There is an Extensor, a Rectus, and two Bicipites. One remarkably thin Muscle arises from the Coccyx, and passes under the Skin of the Extre- mity to its insertion nearly opposite the Heel. It bends the Leg, and extends the Foot. In the Sea Tortoise, the Muscles of the Foot, and also of the Toes, are chiefly Aponeurotic. In the Frogy few Muscles belong to the Spine. A Muscle analogous to the Coccygeus draws the Coccyx into the same direction with the Spine. There is a sort of Sacro-lumbalis, which is fixed to the Transverse Processes of the Vertebra?, and extends as far as the Head ; an Obliquus Superior, a Rectus Anterior, and Intertransversales. The Abdominal Muscles, on account of the want of Ribs, are inserted into the Sternum. There are few Muscles belonging to the Head ; most of those inserted into 230 OF THE MUSCLES [PART II L into it are likewise employed in moving the Superior Extremities. Anterior Extremity. Of the Muscles of the Shoulder, the Serratus Magnus arises from the Head and Trans- verse Processes, and goes to the Scapula. The Pecto- ralis Minor is wanting. The Levator Scapulae arises from the Occiput. The Omo-hyoideus is present, but the Trapezius is wanting. There is a Rhomboideus, but no Subclavius. The Muscle analogous to the Ster- no-mastoideus goes from the Scapula to the Head. The Muscles of the Arm consist of a Pectoralis Major, and an assistant to it; a Latissimus Dorsi, a Subscapu- laris, supplying also the place of the Coraco-brachialis, and a Deltoid. The Supra and Infra Spinatus, with the Teres Major and Minor, are absent. Of the Muscles of the Fore-arm. A Sterno-radialis supplies the place of the Biceps. There is no Brachialis Internus, but a large Triceps, a Supinator, and a Pronator. The Muscles of the Hand are similar to those in Mammalia. The Thumb has an Extensor, but wants all the other Muscles. Posterior Extremity. The Psoas Parvus is wanting, but there is a Quadratus Lumborum which moves the Os Ilium. There is only one Gluteus, which supplies the place of the Medius. The Pyriformis, the Gemini, and Obturator Internus, are wanting ; a long Quadra- ius Femoris, no Psoas Magnus; an lliacus Internus, Pectinalis, three Adductors, an Obturator Externus, though no Foramen Thyroideum. Of the Muscles of the Leg, the Muscle supplying the place of the Vasti and Cruralis has only two heads. The Rectus PART III.] OF REPTILES. 231 Ilectus is wanting. The Biceps has only one belly, and is fixed to the Tibia, there being no Fibula. There is a Se- im-membranosus, Semi-tendinosus, Gracilis, but no dis- tinct Popliteus. Muscles of the Foot and Toes. The^ Gastrocnemius has only one belly ; there is no Soleus nor Plantaris. The Tibialis comes off from the Os Femo- ris, and has an assistant which arises from the Tibia, and goes to the long Bone of the Tarsus. There is a Tibialis Posticus, but only one Peroneus. The Exten- sor Longus Digitorum, and Flexor Proprius Pollicis, are wanting. There is a distinct Extensor Brevis Di- gitorum, Superior and Inferior, Interossei, and a Flexor Digitorum Communis. OF THE INTEGUMENTS. 1 HE Integuments of Reptiles consist of simple Skin, Scales, Rings, or Shields, and all of these covered with Cuticle. The greater number are covered witli Scales. The surface of the Body differs from that in. the former classes, in having neither Hairs nor Fea- thers. In the Turtle, the Epidermis is only distinct upon the Neck and Limbs ; in other parts of the Body, it is incorporated with the Shell. In the Frog and Sa- lamander, the Cuticle is a Mucous Membrane, which separates in tatters at different seasons of the year. Lizards, 232 OF THE INTEGUMENTS [PART III. Lizards, both of the water and land kind, frequently change their Skin, which is pulled off chiefly by the assistance of the Feet. In Snakes, it conies off at moulting seasons, forming what is called the Snake's Shirt. In the Tortoise, the Shell never changes. The Scales vary according to the kind. In the Tor- toise, they are of a Horny nature, differing in hardness and figure. In the Crocodile, they are Osseous. In a great part of Lizards and Serpents, they are small plates of Skin, with the Cuticle between them. In Reptiles with Scales, as the Lizards, the Skin is dry. In those with naked Skin, as the Frog and Salamander ^ it is moist, being covered with a viscid fluid. In Serpents, there is a strong Skin under the Scales, intimately connected with the Muscles. The Cellular Substance, more or less loose in Rep- tiles, connects the Skin to the parts underneath. In the Frog and Toad, the Integuments are remark- able in adhering to the Body at certain points only, and there, chiefly by Vessels and Nerves, viz. about the Mouth, Linea Mediana of the Body, Aim- pits, and Groins. In other parts, the Animal lies loose in the Skin, as in a Bag. Between the Epidermis and Skin, and under the Scales, the Corpus Mucosum is situated, which varies in colour, having all the different tints in the different in- dividuals of the class. In the Camcleon, some Frogs, &c. the colour changes occasionally, in consequence of light, heat, effects of passion, c. In a Toad kept constantly in the light, the colour changes to a pale green 5 while the same kind of FART III.] OF REPTILES. 233* -of Animal, lurking in the earth, acquires the colour of the substance which surrounds it. Reptiles have likewise their Papilla Nervosce, but these are found chiefly in the Feet. The Glands of the Skin are more visible in this than in some of the preceding classes. In the Lizard, there is a range of Follicles under each Buttock, which dis- charge a viscid humour. In the Toad, Glands are ir- regularly dispersed over the Skin -, and in the Salaman- der, along the Back, which throw out an acrid matter, especially when the Animals are irritated ; yet these Reptiles are often handled with impunity. The Panniculus Carnosus exists in the Neck of the Turtle, and some appearance of it is observed in the Neck of the Frog / but in the Body of the Animal, it is wanting. The Claws on the Digits of the individuals of this class, are wanting wherever the Animal does not use its Feet for seizing its prey, or for walking, as in the Tortoise, Frog, &c. OF THE BRAIN, \ 1 HE Brain of Reptiles, consisting, as in the former classes of Animals, of Cerebrum and Cerebellum, i,s extremely small in proportion to the size of the Cra- VOL. IV. P OF THE BRAIN [PART III, iiium. In some, it is several thousand times less than the Body, and without being divided into Circumvo- lutions. It is covered by the same Membranes as in Mamma- lia and Birds, but the Dura Mater has no Processes. The Cerebrum consists of four roundish eminences, viz. two Hemispheres, and two Thalami Optici which are remarkable in their situation, being placed behind the Hemispheres. It has Lateral Ventricles, with Corpora Striata, and a Ventricle besides, in each of the Thalami, which communicates with the third. This last has an Anterior and Posterior Commissure, but the Nates and Testes are wanting. The Cerebellum lies behind the Cerebrum, and has no Arbor Vitas. A fourth Ventricle exists in the Turtle, and probably also among the other orders of the class. The Spinal Mai-row, in most of the Species, is of great size when compared with the Brain. The Olfactory Nerves arise from the Anterior Extre- mities of the Hemispheres, and go to the Nose, after the same manner as in Birds. The Canals receiving them have a common opening from the Cranium. The Optic Nerves are less or more connected, as in the two former classes ; but there is scarcely any union of their Medullary Substance. The Third Pair also agree in general with those in Birds and Mammalia. The Fourth are nearly similar in all red-blooded Animals. The Fifth, as in the for- mer Animals, are also divided into three Branches. The Sixth agrees with those of Mammalia and Birds, Of the Seventh Pair, the Portip Dura is small, there- being PART III.] OF REPTILES. 235 being little soft substance in the parts of several of those Animals on which this Nerve is dispersed. The Portio Mollis is smaller or larger in proportion to the extent of the Organ of Hearing. The Eighth and Ninth have nothing remarkable. The Great Sympathetics have evident Ganglia, like those of Birds,, and are also con- nected with the neighbouring Nerves. They form a Cardiac Plexus, a Ramus Splanchnicus, and are at last lost upon the origin of the Tail. The Cervical Nerves, in the Tortoise, are distributed nearly as in Mammalia. The three last pairs enter into the composition of the Brachial Plexus. In other Reptiles, the Nerves vary in number and distribution, according to the number of the Cervical Vertebrae, and the presence or absence of the Ribs. Of the Brachial Plexus, the three last Cervicals, and first Dorsal, go to the Anterior Extremity. In Frogs, instead of a Plexus, a single large Nerve goes to the Anterior Extremity. In Serpents, the Brachial Plexus is wanting, there being no external Members. There is no proper Diaphragmatic Nerve in any of the class. The Dorsal and Lumbar Nerves agree in number with that of the Vertebrae, The Sacral and Caudal Nerves are not very distinct. They lose themselves in the Bones, Muscles, and Skin of the posterior parts of the Body. The Posterior Extremity has the same distinction of Obturator, Anterior Crural, and Sciatic Nerves, as in Mammalia ; but they vary a little in their origins and distributions, according to the shape of the Mem- ber. In the 2?rog> these Nerves are readily traced. P2 OF OF THE EYE OF THE EYE. J HE Eye of Beptiles has been little attended tq. There is some variety in the Eye-lids of the different orders. The Tortoise, Crocodile, and Frog kind, have three, as in Birds. The third is proportionally the largest. Some Reptiles with Feet, and the Serpents, have no Eye-lids, the common Integuments forming a kind of window, behind which the Eye moves freely. The Lacrymal Gland is as variable here as the Eye^ lids. In the Sea Turtle, it is large and lobulated. The fresh water Turtle^ the Frog, and Toad, have Glands of diminutive size. In Serpents, the Lacrymal Gland is wanting. In the Turtle and many Lizards, there is an Osseous J&ng on the fore part of the Eye, composed of different plates, as in Birds. The Irisy in Reptiles, generally presents a beautiful gilding. The Ciliary Processes vary in length in different Rep- tiles. In the Turtle, they are observed with difficulty, but they leave a distinct impression upon the Vitreous JJumour. In the Crocodile, they are prominent, and have a Plexus of {Mood- vessels, which are very distinct^ 3y seen. The Lens is nearly of the same form as in Birds. ^he Optic Nerve passes through the bottom of the FART III.] OF &EPTILES. 237 Eye by a found hole, and* after entering the forms a Tubercle, from the edges of which the Retina is sent off. In the Tortoise and Crocodile, six Muscles surround the Optic Nerve, and serve for the different motions of the Eye. In the Frog and Toad, there are only three$ united into a Funnel which embraces the Nerve. OF THE EAR. J HE Organ of Hearing varies more in this, than in any other class of Animals. There is no External Ear not Meatus Externus in Reptiles. The Crocodile is the only instance given of a sort of External Ear, and two fleshy Lips for an External Meatus. The Membrana Tympani is present in some of the class, and wanting in others. In the Turtle and Frog 9 it is upon a level with the surface of the Body, and is Covered by the Integuments. In the former, it is com- posed of a Cartilaginous Plate, and in the latter, a$ well as in the Toad y it is distinguished by differing in colour from the rest of the Skin. In the Lizard, the Skin over the Tympanum is known from its transparency, like the Cornea; but in, tnany, as the Chameleon, the Membrana Tympani is wanting, or cannot be distinguished from the rest of P 3 the 238 OF THE EAR [PART UL the Skin. It is wanting, also, in the generality of Ser- pents. A Tympanum) Eustachian Tube, and Semicircular Ca- nals, are present in the Turtle, frog, and in mostLizards. In the Turtle, the Tympanum is in some measure di- vided into two parts by a contraction, which is more distinct in the Crocodile, where the inner apartment has Cells, somewhat like those in the Mastoid Process in the Human Species, but larger. In Lizards, the Frog, Toad, &c. the Tympanum is Membranous behind, and has a short but large Eustachian Tube, which commu- nicates with the Mouth. There is neither Tympanum nor Eustachian Tube in Serpents, and a few others j but a rudiment of a Carti- laginous Ossiculum exists in some, which is inclosed in Muscular matter, the inner extremity occupying the Fenestra Oval is. In the Turtle and Lizards, as in Birds, there is a simple Ossiculum Auditus, with a small Cartilaginous Stalk, which is joined to the Membrana Tympani. The Frog and Toad have two Cartilaginous Ossicula, one joined to the Membrana Tympani, the other articulated with it, and with the Fenestra Ovalis. In Serpents, there is a rudiment of an Ossiculum, the outer end of which touches the Skin, the inner the Fe- nestra Ovalis. Of the Muscles of the Ossicula, little is known in Reptiles. The Semicircular Canals, in many of the individuals of this class, approach to a circle ; each has an Am- pulla, and there is a Sac in place of a Vestible , but the Fenestra Rotunda, and a complete Cochlea, are wanting, though PATLT IIL] OF REPTILES. though there is the vestige of the latter in some of the class. In the Tortoise and Lizards, the Sac contains a quantity of chalky matter, which, in the Crocodile and some other Lizards, is formed into three small, soft, stony concretions j and there is a vestige of a Cochlea formed by a prolongation of the Sac. It is of a conical form, is slightly curved, has a Cartilaginous partition divid- ing it into a double Canal, and is something similai* to that in Birds. There is a vestige of it also in Ser- pents. In the Frog, Toad, and Salamander, the Sac contains also a Cretaceous Matter. The Membranous Labyrinth has many Blood-vessels, which are very visible in some of the large Reptiles. It has also Nerves which are analogous to the Portio Mollis in Man, and these are plentifully dispersed upon the Sac and the Ampulla?. OF THE NOSE. 1 HE Organ of Smell is legs extensive in Reptiles than in the former classes. Some have two or three Cartila- ginous Eminences, covered by the Schneiderian Mem brane ; others merely a thickening of that Membrane. These eminences are somewhat analogous to the Con- ehae of warm-blooded Animals, and divide the Cavity of the Nose into so many Fossulas ; but they have no Osseous Laminae. P 4 The 240 OF THE NOSE [PART III. The Nostrils have some Muscular Fibres, which give them a small degree of contraction and dilatation. The Internal, or Posterior Nares, are placed farther for- wards than in other Animals. In the Crocodile, on the contrary* they are far back. There is no Velum Palati. The Foramen Incisivum is considerable in some, as the Turtle , Frog, Crocodile, and Salamander ; but in others, it is not perceivable. The Nerves here are much the same as in Birds. In the Turtle, the Olfactory is a strong, though slender Nerve ; the Ramifications are easily traced in the Cavi- ty of the Nose. OF THE MOUTH. JL ONGUE. -The Tongue here varies in the shape, size, and general appearance. In some, it is very extensible ; in one or two rare instances, it is so much fixed down, that its existence in such has been denied. Of the Papilla, there is only one kind, there being nothing like Glands placed in Calices. In some of the class, as the Turtle, many Lizards, &c. it is closely covered, at its anterior margin, with long, soft, conical Papillae, which give the appearance of Velvet. In a great part of the Lizard tribe, the Tongue is capable of being considerably elongated, in consequence PART III.] OF REPTILES. consequence of the action of Muscles connected to the Os Hyoides, &c. In the Frog and Toady the Tongue is large, fleshy, smooth, and covered with Mucus. In the state of rest, it is doubled upwards and backwards in the Mcuth. In seizing the prey, it is thrust so far out of the Mouth, as to lay hold of Insects or other Food, by doubling it- self down. In the Crocodile, the Tongue is quite fleshy, and has very short Papillae, but is so fixed down, as to be scarcely observable. In the Salamander, it is fixed as far as its point, motion being only allowed in the lateral parts. In the common Lizard, the Tongue is remark- able for its extensibility. It is forked at its extremity, and terminates by two long semi-cartilaginous, but flexible points. The Tongue of the Chameleon is wrinkled transverse- ly ; is club-shaped and hollowed above. It is concealed in a sheath, and covered with a glutinous fluid, and is thrust five or six inches from the Mouth in catching Flies, &c. In Serpents, the Tongue is round and slender, re- markably smooth, has a horny appearance, and is fork- ed at its anterior extremity. In most of the Species, the root is inclosed in a Membranous Sheath, and can be thrust out to a considerable extent. Salivary Glands. In some Reptiles, as the Turtle and many Lizards, though not in the Lizards of this country, the Tongue is composed, in a great measure, of a thick Glandular mass, covered with innumerable Tubes OF THE MOUTM [PART IM. Tubes united at their basis, and discharging a secreted liquor from their other extremities. The Amphibia of CUVIER, viz. the Seal and Walrus, have the same apparatus, but not in the same situation-, being directly under the Tongue. Besides these Glands, some Serpents, viz. all with Tusks or Fangs in their Upper Jaw, have others which corre- spond with the Salivary Glands of Mammalia. They are placed behind each Orbit, and have two Muscles, which, by raising the Tusks, compress the Glands, and push the venom through Canals in the Fang*, which terminate by an oblique opening at their point, and serve as Excretory Tubes to the Glands. OF THE HEART AND BLOOD- VESSELS. THE general structure of the Heart is the same among the different Animals of the class, but there is some variety among the different orders. The Turtle tribe, -the Lizards, and many of the Serpents, have two Au- ricles, and an appearance of two Ventricles. In the Frog kind, there is but one Auricle and one Ventricle. In many Reptiles, the Auricles are proportionally much larger than in the two preceding classes. The Golum- nse Carneae are less raised. The Right Auricle receives the Blood from the Body, the Left from the Lungs. The PART III.] OF REPTILES, 243 The Ventricles have Cavities small in proportion to their external appearance, owing to the great thickness of their walls. Internally they have, in the three first or- ders or tribes, numerous Columnse Carnea?. In the Turtle kind, there is a strong Pericardium, united to the Peritoneum, in the manner the Diaphragm is united to the Pericardium in the Human Body. The two Auricles are separated by a complete parti- tion. The two Cavse terminate in the Right Auricle, where there are two Valves, and the Pulmonary Veins in the Left, where there are also a pair of Valves. Each Auricle communicates with a corresponding Ven- tricle. The two Ventricles communicate by a large opening. In the Right Ventricle, there is a hollow Muscular Valve, which prevents the return of the Blood to the Left. The Arteries arise from the Right Ventricle only. They come off in three large Trunks, or there are three Aortas, two of which go to the Abdomen. The Right is the proper Abdominal Aorta; the Left, the Ductus Communicativus of MERY ; and Third, the Pulmonary Artery. In consequence of this structure, fne Aortic Circula- tion can proceed without interruption while the Animal is under water, which is different from what happens in the two former classes. In the Lizard tribe, the Pericardium adheres, as in the Tortoise, to the Peritoneum, which covers the con- vexity of the Liver. The Auricles are in general simi- lar to those of the Tortoise, but the Ventricle is observ- ed to vary much in certain Genera and Species of this order. $4* OF THE HEART, & c . [Pun til. order. In others, particularly in the Crocodile, it is more complex, being formed into three apartments, which have numerous orifices in their partitions, and these receive the Blood from the Right and Left Au- ricles, as in the Tortoise, where also Valves are placed to prevent its return. From the different apartments the three great Arteries go out, viz. the Right and Left Aorta, and Pulmonary Artery. In the Serpents, the Heart is more simple than in the Crocodile ; there are two Auricles and a Ventricle, with two apartments, arid a large communication, or the Heart here resembles, in structure, that of the Tor*- toise ; there are, within the Ventricle, also two Auricular Valves, and many Columnse Carneae ; the former pre* venting the return of the Blood to the Auricle, the latter mixing the Blood from the Lungs, and that from the rest of the Body, intimately together. In the Frog and Salamander Aquatica, the Heart has only one Auricle and one Ventricle, with some Colum- nae Carneae, but these not detached from the sides of the Ventricle. The Ventricle opens into the common Trunk of the Ar^ry by a single orifice. \m PRINCIPAL BLOOD-VESSELS. Tortoise. From the Right Ventricle two or three large Arteries arise, which are joined together for a short space. The Pulmonary Artery arises on the left side, and soon divides into right and left Branches which go to the corresponding Lungs. The Trunk of the Aorta commences at the right side of the base of the FART III.] OF REPTILES. the Heart, and immediately divides into the right and left Posterior Aortae, or sometimes the two Aortse arise separately. The Right Aorta furnishes the Aorta Anterior, that soon divides into two Branches, of which, one is the common Carotid, the other is the Subclavian. The Carotids are dispersed like those in Mammalia. The Subclavians are also nearly as in Man. Lizards. In the Crocodile, there are three principal Arteries, each with two Semilunar Valves. 1. The Pulmonary Artery on the left side. 2. The Aorta Pos- terior Sinistra. 3. The Aorta Posterior Dextra. The three Arteries are joined together for some space, as in the former order, Serpents. The Lung being single here, and the Ex- tremities wanting, renders the Blood-vessels more simple than in the former orders. Frog and Salamander. The Aorta soon divides into two Branches ; each of these produces a Pulmonary, a Carotid, and Subclavian, and Arteries similar to the Intercostals, then turns back, and unites with its fellow. The Trunk resulting furnishes the Cceliac and other Arteries, which generally come off from the Abdominal Aorta. VEINS. The Turtle tribe have two Posterior Cavae, whic,h 5 after passing the anterior part of the Liver, are each joined by an Anterior Cava of the same side, formed |ay the common Trunk of the Jugular and Subclavian. All OF THE HEART, &c. [PART III. All go into a Receptacle, which opens into the Right Auricle by a chink bordered by two Valves. The Pulmonary Veins unite in one Trunk, which goes into a similar Reservoir; and this opens into the Left Auricle, where there is also a Valve. In the Lizard and Serpent tribe, there is only one Posterior, but two Anterior Cavae, which open into a similar Reservoir ; and this goes into the Auricle by a, chink which has two Valves. The Pulmonary Veins are similar to those of the former order. In the Serpents, there is but one Pulmonary Vein, which goes into the Left Auricle. In the Frog and Salamander, the Veins have a distri- bution similar to the Arteries. There are two Anterior Cavae and a Cava Posterior, all ending in one Auricle* OF THE ABSORBENTS. As in Birds, the Transparency here, joined to the want of Glands, long prevented the Absorbents from being discovered. The structure is similar to that in the Ani- mals of the former class, and, like the Absorbents in these also, they have numerous Valves, but no Glands are found in any part of this system. The Plexus these Vessels so frequently form, are considered by some as supplying the place of Glands, Here ? PART III.] OF REPTILES 4 . 247 Here, as in Birds, the Lymphatics of the Viscera of Digestion and Generation, and those of the Posterior Extremities, join in a plexus, into which all the other Lymphatics of the Body pass. From each of these Plexus a short Canal goes out, which terminates in the Jugular Veins, or in the angles they form with the Sub- clavians. In the Turtle, the Absorbents of the posterior parts of the Body go to a Plexus, which surrounds the Right Aorta, and then into a Reservoir situated more for- wards, under the Left Aorta. From this, two Thoracic Ducts, or rather several principal Branches, arise, which advance to those under the Clavicles. Here they join with the Lymphatics of the Anterior Extremi- ties, and of the Head and Neck, and form two very in- tricate Plexus. From the Plexus of the right side, two Branches go. out, which terminate in the Jugular Vein, near the angle it forms with the Subclavian. The Left sends out but a single Duct, that opens into the angle of the two Veins. The Absorbents under the Perito- neal Coat of the Intestines, run in straight parallel Branches, according to the length of the Bowel ; and a good injection shews them to cover almost the whole surface of the Gut. The inner surface is no less plen- tifully supplied with them, though here they have more the appearance of small Cells. From the Intestines, they go in company with the Mesenteric Blood-vessels, and form frequent Plexus and communications. At length they anastomose with the Absorbents of the other parts of the Abdomen, and Discharge their contents into the Thoracic Ducts. op 243 ORGANS OF VOICE, & c . [PART III. OF THE ORGANS OF VOICE AND RESPIRATION. L HE Larynx of Reptiles, like the Superior Larynx in Birds, is composed of different pieces ; but the appear- ance varies in different kinds of Reptiles, and some- times in the different sexes of the same Species. TJiere is no Inferior Larynx in this class. Reptiles have neither Epiglottis nor Papillae, though, in the Crocodile, there are the rudiments of the former. The Larynx of the Crocodile has five Cartilages enter- ing into its composition. The Glottis is purely Mem- branous. The Ligaments of the Glottis are present in all the Animals of the class, but they have neither Lips nor Palatum Molle, and in general no voice. The Tortoise, several Lizards, and Serpents, can only blow. The Frog tribe, especially in the time of their amours, are enabled to croak, or, when in pain, they sometimes make a sharp squeaking noise, hav- ing a Larynx adapted to these purposes, the vocal Li- gaments and Ventricles of the Larynx being of great proportional size. The Males of some Species of Frogs have one or two Sacs, either in the Throat or Cheeks, which they inflate, in time of copulation, by means of a Foramen near the chink of the Larynx, opening into each of the Sacs. Here, also, the Rima Glottidis is larger, and the Trachea longer, than in the Female. The Trachea, in Reptiles in general, is formed of Cartilaginous PART III.] OF REPTILES. 249 Cartilaginous Rings, though with some exceptions, as in the Crocodile, Chameleon, and Serpents. In these last, it has the appearance of being a complete pipe. The proportion of the Bronchi, compared to the Trachea, is as in Birds ; but in Serpents, there are large dilatations. In some of the Turtle and Crocodile kind, the Bron- chi form convolutions ; and in some, the Trachea di- vides so soon, as to appear to be double. In most other Reptiles, the Bronchi are very short. For the most part, the Bronchi do not divide, and commonly do not enter into the substance of the Lungs, but terminate abruptly in them by one or more large orifices. The Lungs here, as in Birds, are in the same com- mon Cavity with the other Viscera, but vary more in shape and size than in the two former classes. They form most frequently two oval Sacs, which, in the Turtle kind, extend by the sides of the Spine, as far as the Pelvis, and above all the other Viscera. They dif- fer from those of Birds by the greater size of their Ceils, and the looseness of their texture. In the Turtle, they are more complicated than in the rest of the individuals of this class, approaching more in their structure to the Lungs of Birds. The Branches of the Bronchi communicate, each by an orifice, with a particular Sac, the walls of which form Polygonal Cells, varying according to the kind of the Animal. In the Crocodile, the Cells are smaller than in. the Turtle. In Lizards, Frogs, and Serpents, the Lungs have, at their anterior part, a Cavity, the walls of which are VOL. IV. Q formed 250 ORGANS OF VOICE, &c. [PART III. formed of Polygonal Cells, containing still smaller Cells. Posteriorly, they appear to terminate in a simple bag. Serpents have, for the most part, a single Lung, and here the Trachea terminates directly into it, without dividing into Bronchi. In the young of some Reptiles, as the Tadpole, which are produced in the water, and metamorphose in their first state, in place of Lungs, there are two Bodies, the Appendices Fimbriatte, like Branchiae or Gills, hanging loose by the sides of the Neck. These are gradually taken into the Thorax, in which they afterwards disappear. The Siren Lacertina, and the Proteus Anguinus, are supposed to possess both during life. In Reptiles, part of the Blood only goes to Che Lungs, the rest of the mass going to the other parts of the Body, a circumstance different from what happens in the two former classes. The Pulmonary Blood-vessels ramify on the Lungs, and serve also as Bronchial Vessels, which are not found here. In Reptiles in general, where the Ribs are either confounded with the other parts of the Thorax, or are so deficient as to be unable to contribute to Respiration, this process is observed to be effected by the Animal shutting the Mouth, dilating the Throat, and produc- ing a void, in consequence of which the Air enters by the Nostrils. The Throat is next contracted, so that it forces the air into the Lungs. Expiration is owing to the action of the Muscles of the Belly. In opening the Thorax of the Turtle or Frog, the Lungs remain distended for some time, owing to the parts about the Throat acting as a Valve. OF PART III.] OF REPTILES. 251 QF THE ALIMENTARY CAtfAL. HERE, as in Birds, the Viscera of the Abdomen are in the same Cavity with those of the Thorax , of course, the Peritoneum and Pleura are blended together. The former Membrane differs from the latter in Reptiles, in being sometimes of a black colour. The Diaphragm is wanting. The Alimentary Canal is very similar to that in Birds. The Pharynx and E- sophagus are nearly of the same .diameter, and are wider, in proportion to the -size of the Stomach, than in the two former classes ; and are rendered still wider than at first sight they appear to be, by being full .of Rugae, which vanish when the Animal swallows. The Esophagus of the Turtle is covered with long pointed Papillae, of a white colour and firm consistence, and turned towards the Stomach, as if to prevent the Food from returning. In the Lizard tribe, the Stomach is of a globular form. In the Crocodile in particular, it resembles that of the Gizzard of Granivor.o.us Birds, in the closeness of its orifices, and thickness of its substance. The Esophagus of Serpents is of great size, as they frequently swallow Animals larger than themselves, and often retain them there for days or weeks, allowing them to pass to the Stomach by slow degrees. The proportional length of the Intestinal Canal, com- pared with the Bodies of Reptiles, is still less than in Q2 the 252 OF THE ALIMENTARY CANAL [PART III. the former class of Animals. In some of the Turtle kind, it is about five times the length of the Animal ; but in some other Reptiles, as the Frog, it is scarcely twice ; and in some of the Serpent tribe, as the Coluber Matrix, it is not equal to the length of the Creature. The small Intestines are generally much contracted In their diameter, while the large are as much dilated, though sometimes the reverse, as in the Hawk's- bill Turtle. In Turtles, in Lizards, in the Frog tribe, and Snakes, there is a Vermiform Process, but rarely any Caecum. Almost the whole of this class have a Circu- lar Fold or Valve between the small and great Intes- tines. The inner part of the Canal has Plicae, varying in the different kinds, and is lined with a large quantity of Mucus. In the Tortoise, there are no Cells in the great In- testines ; but the Canal in this, and some other Ani- mals of the class, are full of Fossulas. In Lizards, and in the Frog and Toad, the Colon is cylindrical, and much larger than the small Intestines. In some of the Lizards, as the Crocodile of the Nile, the Plicae of the small Intestines have a zig-zag appearance. In the Chameleon, the small Guts equal the size of the Colon ; and in the Crocodile, the Colon little exceeds the small Intestines. In Snakes, the small Intestines are serpentine, and nearly equal in size with the Colon. They have longi- tudinal Plicae, while the Colon has irregular Rugae. The Intestinal Canal, in Reptiles, terminates in a Cloaca, which is nearly of the same nature as in Birds. The Anus, in some, as the Tortoise, is placed under the PART III.] OF REPTILES. 253 the Tail. In others, as the Frog and Toad, which have no Tail, it is above the extremity of the Back. There are some varieties in the situation and attach- ments of the Mesentery. In the Tortoise, it is conti- nued from the Mesocolon, and is not connected direct- ly to the Vertebrae. In Lizards, the Mesentery and Mesocolon come off from the Vertebrae. Serpents have no Mesocolon Transversum. Reptiles in general may be said to want the Omen- turn, yet many Lizards have a substance resembling it, charged with Fat ; and the Fatty Lobes, attached to the Testicles and Ovaria of Frogs , are considered by some as a kind of Omentum, while others think them connected with the parts of Generation, on account of the great increase of bulk at pairing-time. OF THE LIVER, PANCREAS, AND SPLEEN. 1 HE Liver is present in the whole class,* and is pro- portionally larger than in Mammalia or Birds, extend- ing generally to both Hypochondriac regions. It is still less divided than in Birds. In some, it has two Lobes ; but in many, it has none. It is connected to the Body by tbe Peritoneum, as in Mammalia. The colour is commonly bordering upon yellow. Q 3 The 25* OF THE LIVER, &c. [PART til. The Gall-bladder is also present in all Reptiles, but is of smaller size than in the former class. In the Tortoise and Crocodile, it is closely connected to the Liver ; in Serpents, it lies at a distance from that \ iscus. As in Birds, the Trunks of the Hepatic and Cystic JDucts are separate from each other, though with several exceptions. Hcpato-cystic Ducts go commonly into the Body of the Gall- bladder i or into its Neck, or the beginning of its Duct. In the Crocodile, the Hepatic Duct sends a Branch to the Neck of the Gall-bladder, and unites with the Cystic near its termination in the Intestines. In the Turtle, the Hepatic Duct gives a Branch to the beginning of the Cystic $ but the two Canals open separately into the Intestine. PANCREAS. The form and situation of the Pancreas varies much in Reptiles. In some, as the Tortoise, it is triangular ; in others, as the Crocodile, lobed ; and in others, as Serpents and Frogs, it is irregular, and in the former, is situated on the right side of the Intestines. The Pancreatic Duct is single in some, and double in others. In some, as the alumander Terrestris, it is inserted before, and in others, as the Crocodile^ after the insertion of the Biliary Duct. SPLEEN. PAKT III.] OF REPTILES. 255 SPLEEN. The figure of the Spleen is also Very various. In the Turtle, it is reniform ; in the Frog kind, spherical ; in Lizards and Serpents, it is of a long form. It is less intimately connected to the Stomach here* than in the former classes. In some, it is fixed to the left side of that Organ, as in the Salamander ; in others, to the Anterior Arch, as in the Chameleon ; or to the beginning of the Intestines, as in the Tortoise and Ser- pents. In the Frog, it is above the Stomach, between the plies of the Mesentery. In the Crocodile, at the left portion of the Intestines. OF THE KIDNEYS. I HE Kidneys here resemble those in Birds, but differ from those in Mammalia, in wanting the Medullary Substance, Infundibulum, and Pelvis. They vary in situation and general appearance in the different orders. In the Turtles and Lizards, they are in the Abdomen. In Lizards strictly so called, they are in the Pelvis. In the Frog tribe, they are more forwards. They are co- vered, on their inferior part only, by the Peritoneum. In Serpents^ the right is considerably farther forwards than the left. In some, as the Turtles, they are collect- Q4- ed 25G OF THE KIDNEYS [PART III. ed into a mass. They are long and flat in Lizards and Frogs. In the Serpents, they form a sort of chain. The Ureters arise as in Birds. In the Turtle, they terminate in the beginning of the Urethra, from whence the Urine goes into the Bladder. In many of the /- zarrf tribe* -the Ureters terminate in a Bladder, which is of considerable extent, and the Urethra opens into a Cloaca. In the Crocodile, the Ureters end in a Cloaca, there being no Bladder. In Serpents, each Ureter di- lates into a Vesicle, which terminates in a Cloaca. In general, they end in a Bladder or a Cloaca, as the Or- gan happens to exist. The Bladder, when present, re- ceives the Urine at its Neck, or at the beginning of the Urethra, and opens directly into the Cloaca. In the Genus Rana, viz. the Frog and Toad, there are two Bags taken notice of by BLUMENBACH and Cu- VIER as Urinary Bladders. TOWNSON, however, describes the Ureters in these Animals as terminating at the posterior part of the Rec- tum, as in Birds, while the Receptacles here mentioned, and which are of great size, terminate at its anterior part 5 and is of opinion, that the fluid they contain is pure water, which he has frequently tasted. He thinks this fluid is absorbed from the surface of the Skin, and serves the same purpose to these Animals, as fluids do to those which take them into the Stomach by the Mouth ; that the fluid they eject prevents an inconve- nience in leaping. In the Turtle tribe, the bottom of the Bladder di- vides into two Cornua. The Urethra, which is ex- tremely short, opens into the Cloaca. There are two projections PART III.] OF REPTILES. 257 projections in each side, one pierced by the Ureter, the other by the Vas Deferens. From the above it appears the Bladder exists in the Turtle, in many Lizards, though not in all, in Serpents; and that, in Frogs, there are receptacles considered by some as a Bladder, and by others as of a different nature. Near the Kidneys, but unconnected with them, are two small Bodies, considered by some as Renal Glands, by others, as connected with the Organs of Generation. CUVIER looks upon them as a kind of Omentum. In the Turtle, they are attached to the Renal Veins. In. Lizards and Serpents, they are in a ply of the Perito- neum, connecting the Ova and Oviducts. In the Frog, they are fringed Bodies, like the Testes or Ovaria, and fixed to the Emulgent Veins. OF THE MALE ORGANS OF GENE- RATION. 1 HE situation of the Testes in the different orders of this class, is very analogous to that in Birds, being con- stantly in the Abdomen, in the vicinity of the Kidneys. In the Turtles, Lizards, and Serpents, they are variable in their form, and are fasciculated. In Frogs, they are like Granulae closely connected. The Epididymis varies in figure and size in the diffe- rent tribes. As in Birds, the Vas Deferens, coming ut from it, terminates in the Cloaca. In the Turtle , the OF THE MALE ORGANS [PART III; the Epididymis is a large Canal, which forms the Vas Deferens, that runs in a flexuous manner to open in the Cloaca at the base of the Penis. In Lizards, the Epi- didymis is detached from the Testicle^ and forms a py- ramidal Body longer than it. From this the Vas Defe- rens goes along the edge of the Testicle, in a waving direction, to the Cloaca. In Frogs, the Vas Deferens terminates in a Papilla. The Vesiculae Seminales, and Prostate Gland, are riot found in Reptiles in general, The Frog, however, has two large Vesiculae Seminales, In the Turtle kind, there is but one Penis. In most Lizards and Serpents, there are two. In the Frog kind, the Penis is entirely wanting. In the Turtle, it is very large, and in the relaxed state, it is retracted within the Cloaca. It is composed of two Corpora Cavernosa> and has a Groove in its upper surface, instead of an Urethra, the margins of which come so close together in the distended state of the part, as to form a complete Canal. The Penis has two Retractor Muscles, which run from the Pelvis to the under side of the Glans. In Lizards and Serpents, the Penises are short and cylindrical, and commonly surrounded with bristles. In the relaxed state, they commonly lie in a Pouch under the Skin of the Tail. They are erected by the power of the Muscles of the Tail, and appear at the sides of the Cloaca. Two Retractors from the first Vertebra of the Tail return them to their natural situa> lion in the Pouch. The Rattle-snake and Viper have also double Penises $ each is again bifid* and beset with bristles. In PART III.] OF REPTILES. In the Crocodile, the Penis is single, and has a deep Fissure throughout, formed principally of one Corpus Cavemosum. ORGANS OF APPREHENSION. Besides the common Organs of Generation, a few Male Animals have Accessory Organs, by which they are enabled to fix upon the Female. Among those of the Reptile tribe are to be observed, the Spongy Ball upon the Thumb, and part of the Palm, of the Frog kind. They are composed of hard Papillae. By means of these, the Male fixes firmly upon the Back of the Female, which he squeezes when in season, and conti- nues there for days, or even weeks, in the water, till the Semen is ejected, which takes place in both sexes about the same time ; the two fluids mixing together without any copulation. After the Semen is emitted, the Animals separate from each other, and have no connection till the season of their amours returns. OF THE FEMALE ORGANS OF GE- NERATION. ALL Reptiles have two Ovaria, two Oviducts, and one r two Uteri, Th 260 OF THE FEMALE ORGANS {PART III, The Ovaria are commonly more extensive in propor- tion than in Birds. The Ova increase so much in some, as Frogs and Toads, towards spawning-time, as to dis- tend the Abdomen. The Ovaria are fixed by two Jong prolongations of the Peritoneum, to each side of the Spine, as far as the Pelvis. Along the loose edge of the Ligament are arranged the Ova, in some like rows of Beads, in others they are in clusters. The Oviducts are Membranous Tubes fixed by the Peritoneum to the sides of the Spine At their origin, they are delicate; in their course, they become thicker, and, in general, are much longer in proportion than in Birds. In the Turtle kind are two Ovaria, two Oviducts, and two Uteri. The Oviducts are thin and delicate, the LTteri thick and fleshy. Each has an opening into the Cloaca, in which, according to BLUMENBACH, there is an evident Clitoris. In Serpents, the Ovaria are like rows of Beads, and are composed of yellow Vesicles. The Oviducts are much convoluted, and are connected with double exter- nal openings of Genitals, which receive the double Or- gans of the Male. Many of this class, as the Rattle-snake and Viper, are Viviparous, the Ova being hatched in the Cavity of the Oviduct. The Rattle- snakes are known to couple iu August, when they are frequently observed to make a noise with their Rattle, a substance peculiar to this Ani- mal, and consisting of a number of hollow, horny substan- ces, each linked into the one succeeding it, the first co- vering the last Vertebra of ^ie Tail. The Rattle -snake produce? PART III.] OF REPTILES. 261 produces about a dozen of young, commonly in the fnrnth of June. In some of these Animals, living Snakes have been taken from the Belly, several inches in length. In Frogs, the Ova are clustered up, and extremely numerous. They are found to float loose in the Cavity of the Abdomen, previous to their getting into the Ovi- ducts or Uterine Tubes. The Oviducts, in these Ani- mals, are extremely long and convoluted, appearing like so many Intestines. Each begins at the side of the Heart by an open orifice, and terminates by a large Dilatation or Uterus, which ends in a CJoaca. PART PART IV. OF FISHES. OF THE BONES. J 1 ISHES have in general a Spine, extending from the Cranium to the Tail Fins, and have the Fins at the un* der part of the Belly articulated with Bones peculiar to them. The Bones of the Cranium are firmly united together by indistinct Sutures. Jn Osseous Fishes, the Bones are very numerous ; but in several of the Cartilaginous, as the Skate, the Cranium is chiefly in one continued piece. In general, the Cranium bears a small proporr tion to the rest of the Head, but is large when com- pared with the size of the Brain it incloses. Jl is not marked in the inside by the Brain, not being moulded upon it as in Mammalia. The Cranium of Osseous Fishes is broad between the Ears, these Organs being contained in the same com- mon Cavity with the Brain. In Cartilaginous Fishes, the Ears are separated by a distinct Septum. Fishes, as Birds, have a partition between the Eyes, which has been compared to a Vomer ; and this is generally Memr branous, though in some Osseous. In Fishes of the Cartilaginous kind, the Under Jaw differs from that in the Osseous, in not being articulated PART IV.] OF FISHES. articulated with the Cranium, but through the me- dium of the Bone analogous to the Os Quadratum in Birds. In each side of the Cranium of Osseous Fishes, as in Birds, is a great moveable Bone, which supports the Palatine Arches and the Lower Jaw. In the Squalus or Shark kind, the two Jaws are very move- able. Each is composed of a pair of Cartilages, joined at the fore part. The Upper has two Condyles, by which it is articulated with the Lower Jaw. It has also two small Inter-articular Cartilages, Nearly the same structure is found in the Sturgeon. The Teeth of Fishes vary in form, number, and si- tuation, and, strictly speaking, are a set of hard pro- minent Bodies, placed in some part of the Mouth or Throat, merely for grasping their prey, and preventing it from escaping, their Food not requiring manduca-r tion. Some Species of Spams have Front Teeth, simple, and with Fangs fixed in the Alveoli, almost si- milar to those in the Human Body. In general, simple Teeth, with Fangs in the Alveoli, are a continuation of the Alveoli, but differing from them in their structure, and they are covered with Ena- mel, as in Mammalia. In some, as the Squalus, the Teeth are also simple, but joined only to the Gums, and grow in the manner of Epiphyses. In some, the Teeth are conical and blunt ; in others, flat and round, or simply round ; or some have them sharp, and in the form of wedges. In the Shark, the Teeth are very numerous, but without Fangs, and are placed in rows. The front row only is perpendicular, and exposed ; the rest are small* ffi 264 OF THE BONES [?ART IV. er, and turned back, and covered by the Gums, but come forward when any of the front row are lost, so as to supply their place. The situation of the Teeth is very variable. They are placed in the Jaws, or in the Palate, or in the back part of the Septum Narium, or in the Bone which supports the Tongue, or in that which supports the Branchiae, or at the beginning of the Esophagus ; and named, from their situation, Mandibular, Pala- tine, &c. Some, as the Salmon and Pike, have Teeth in all parts of their Mouth. The Squalus Pristis, or Saw-fish, has Teeth in both sides of the sword-shaped Bone in front of the Head. In some, the Teeth are only wanting in cer- tain parts of the Mouth. The Perch has them in every part of the Mouth, excepting the Tongue. The Stur- geon has no Teeth. The number of the Vertebra is also very variable in this class. In Osseous Fishes, the Vertebrae of the Neck are wanting, or not more than three or four. In the Skate kind, they are united into one piece. The Vertebrae of the rest of the Spine varies extremely, being from about 20 to upwards of 100. Some Sharks have above 200. In some, they are cylindrical ; in others, angular ; in others, flattened. They are articulated by their Bodies, having no oblique Processes. The Bodies of the Vertebrae are hollowed out into conical cups, containing a glairy matter. The edges of the cups are joined to those of the contiguous Vertebrae through the whole length of the Spine, by Cartilages composed of concentric Fibres. The last Vertebra is generally PART IV.] OF FISHES. 265 generally triangular and flat, and lies in a vertical direc- tion, corresponding with the Fin of the Tail. Of the Spinous Processes, one set is placed above, and another below, the Bodies of the Vertebrae. Be- tween the Bodies of the Vertebree and Roots of the Superior Spinous Processes, is the Canal for the Spinal Marrow ; while there is frequently a passage between the Bodies and Inferior Spinous Processes for the great Blood-vessels. The Vertebrae are connected to the Head, in Osseous Fishes, by a single Condyle under the Foramen Ocei- pitis, while, in the Cartilaginous kind, there are two Tubercles. Fishes have no proper Thorax, the Abdominal Vis- cera occupying the Cavity of the Trunk, which is form- ed by the Spine and the Ribs where they exist, for few of the individuals of the class possess a Sternum. The number and magnitude of the Ribs vary much here. In some, the size is considerable ; in others, as the Herring, they are like small bristles ; in many, they are forked through the greater part of their length ; in some, double throughout. In most Fishes, the Ribs are articulated with the Bodies of the Vertebras ; in some, they are only fixed to the Transverse Processes. The Anterior Extremities of Fishes are their Pectoral Fins, composed, as Fins are in general, of Osseous Rays, and each of these of several articulations, all of which arc joined by a common Membrane. They are ge- nerally fixed to a Bony substance, which is the only thing analogous to the Scapula, and which is articulated with the upper and back part of the Cranium. In the Skate , VOL. IV. R kind, 266 OF THE BONES [PART IV. kind, they are fixed to the Vertebrae, and give to these Anmals a rhomboidal form. In Osseous Fishes, the Pec- toral Fins form aft angle with the Body, and move ho- rizontally backwards and forwards ; but in the Raja % Sgualus, &c. they are in the same horizontal plane with the Body, and- move less or more in a vertical di- rection. The Abdominal Fins are connected to Bones, which may be compared to the Ossa Innominata, as the Pec- toral are to the Scapulae-; Besides the Bones mentioned above, some Fishes' possess Bones which are placed among the Muscles, and have the name of Ossicula Musculorum ARTEDI* OF THE MUSCLES. 1 HE Muscles of Fishes are distinguished from those of the Animals of the former classes, by receiving less Blood, of course paler in their colour, and by being more uniformly disposed into Layers, and, in general, in wanting Tendons. In Osseous Fishes, the greater part of the Muscles are placed upon the lateral parts of the Body, by whicK they are calculated fur enabling the Animal to move readily to either side. The spaces between the Ribs are occupied by Muscles somewhat PART IV.] OF FISHES. 267 somewhat similar to the Intercostals ; but the Ribs are also affected by the large lateral Muscles of the Body, which are likewise fixed to the Ribs. In the greater number of Fishes there are no Muscles peculiar to the motions of the Head, this being done chiefly by the Lateral Muscles of the Body. The Fins on the under part of the Body, are moved in various directions by small Muscles peculiar to them- selves. Those in the Back have Muscles in pairs, plac- ed before and behind the Fins ; one pair passing from the nape of the Neck to the Fin, another lying between the Fin and the Tail. Where there are two Dorsal Fins, there is an additional pair of Muscles placed be- tween the Fins. In the Raja, there are Muscles for moving the Head upon the Body, and others by which the Snout is mov- ed upon the Head. The Skate has two thick beds of Muscles on the Body, one placed above, and another below ; and these are formed into numerous Fasciculi, which, like the Cartilaginous parts of the Fins, have a radiated appearance. OF THE INTEGUMENTS. 1 HE Integuments here have the same number of Layers as in the former class of Animals. The Cuticle is strong and thick, and is covered by the Scales, which are laid R2 on 268 OF THE INTEGUMENTS [PART IV. on each other like tiles on a house, and exist less or more in Fishes in general. The Scales are found to cover the Cuticle, as the Hair, &c. does in other Ani- mals, but are not, like these substances, frequently changed ; instead of which, they are found to be per- manent, and are said to increase in number as the Ani- mal becomes older. The Cut-is is very thick and strong in the Sturgeon, and in some of the Skate and Shark kind 5 but in Fishes with large Scales, as the Cyprinus and Sparus, it is of a thin and delicate texture. In certain Vertebral Fishes, as the Carp, there are some Muscular Fibres attached to the Skin of the Back, forming a kind of Panniculus Carnosus. In Fishes, as well as in other cold-blooded Animals, there is no Fat under the Skin. In some, as the Sal- mon, there is an oily fluid, in others, as the Moon-Jish, a substance of great thickness, like Lard, under the- Skin, but it is found to be of the nature of Albumen. The Integuments of Fishes have no Vessels carrying red Blood, and but very small Nerves 5 of course, are well fitted for protecting the tender parts within. Upon the surface of Fishes, particularly in such as live in salt water, there are Ducts, varying in number according to the kind, which pour out a Mucus to de- fend the Skin from the penetrating effects of the water. Those destitute of distinct Scales, as the Skate tribe, have this Mucus in greatest abundance. In the Raja and Squalus, a set of transparent Ducts originate from a point on each side of the Animal, di- rectly over the angle of the Jaw, and a little to the outer and PART IV.] OF FISHES. and back part of the Eye. From this, as a centre, the Ducts issue in Fasciculi, and extend in Radii of diffe- rent lengths, between the Skin and the Muscles. They are shut at their origin, have no visible Glands, nor have they any evident communication with each other. Each has an opening of considerable size upon the surface of the Body, where they pour out clear slime in large quantities, to defend the Skin, which, in Ani- mals of this kind, is less scaly than in others. Upon the beginning of these Canals, where they issue from a centre, a large Nerve, the third Branch of the filth pair, is dispersed in radiated Branches, which become suddenly transparent, and vanish in the Coats of the Ducts. Upon the under surface of these same kind of Fishes, there are also Mucous Ducts, of a similar nature with the former, but more irregular in their course. Besides the Ducts mentioned ab.ove, there are others, much larger, upon the inferior or ventral surface, which like- wise discharge Mucus for the defence of the Skin. They are situated at the sides of the Mouth, and upon .the La- teral Fins, and take a serpentine direction. In the Torpedo, the Mucous Ducts are less in number .than in the -Skate, &c. and they only receive part of the jiumerous Filaments of Nerves which go to the former Ducts, the larger portion being spent upon the Electric Organ of this Animal. In Osseous Fishes, as the Cod, Haddock, &c. the Mucus comes from a Linea Lateralis, or Duct on each side of the Body and Head, and extending as far back B3 as 270 OF THE BRAIN, &c. [PART IV, as the Tail Fin. Upon the Head, the Duct divides into Branches, which spread* out upon the two Jaws. From this Duct a number of short Tubes arise, and terminate by openings upon the surface of the Skin. CUVIER describes these Ducts as arising from two Glands placed upon the Head, above each Orbit. OF THE BRAIN, #c. 1 HE appearance of the Brai?i differs much in the dil* ferent Species. It is always remarkably small in pro- portion to the size of the Body, though the Nerves are as large, when compared with the parts on which they are distributed, as in the former classes. The Brain here never fills the Cranium, there being always a large space occupied by a salt fluid, contained in loose Cellular substance, which surrounds the Brain, and supplies the place of the Tunica Arachnoidea. The Brain, in Fishes, somewhat resembles that in Birds, only the posterior bear a greater proportion to the anterior parts, and there is often a Tubercle behind, forming a kind of second Cerebellum, and which is pe- culiar to Fishes. The Brain, in general, is divided into Cerebrum and Cerebellum, and these have their Ventricles somewhat as in Mammalia. The Lobes are rnoxe numerous than in. PART IV.] OF FISHES. 271 in the former class, but there is -great. variety in diffe- rent Fishes. The Cerebrum constantly forms two Lobes or Hemi- spheres, which are laid by the sides of each other, and are smooth and without convolutions. The Cerebellum is in one Lobe,, and larger in proportion than the Hemi- spheres, often surpassing them in size. Each of , the Hemispheres has a Ventricle, with a kind of Corpus Striatum $ and there ; is also something like a Third and Fourth Ventricle, as in Mammalia. The Thalami Optici are constantly situated, as in Birds, under the Hemispheres, and, as in them also, each contains a Ventricle. There are no distinct Tubercula Quadrigemina, un- less Tubercles situated under the Hemispheres, in some Fishes, are taken for such. The Nerves, as already noticed, do not bear propor- .tion to the size of the Brain, but to^the parts to which .they are destined. They differ from the Nerves of the Animals of the former classes, in having no Ganglia, though in the Genera (Jyprinus and Gadus, something like Ganglia are found in the Olfactory Nerves. In certain Fishes of the Genus Gadus, as Cod, Had- dock, and Whiting, there are numerous small roundish Bodies, contained in little Vesicles on the surface of the Brain, on the anterior extremity of the Spinal Mar- row, and on some of the principal Nerves, and within the Skin covering the Fins, These are described by DR MONRO in his Work on Fishes, but their use is unknown, R4 The 272 OF THE BRAIN, &c. [PART IV. The Olfactory Nerves, in certain Fishes, as the Skate and Shark, are so large at their origin, as to have been considered by some the proper Brain, or at least its An- terior Lobes. At their roots, each forms a large Bulb, from which the Nerve passes towards the Nares. In some, the Nerve is at first slender, and afterwards forms a large Ganglion ; in others, it is thick and short, and surrounded with Cortical Substance. It terminates by a Ganglion, which is separated from the Nostril by a Cribriform Membrane, which gives passage to the Nerves into the Nose. In Osseous Fishes, the Olfactory Nerves are long and slender, in some surrounded by Cartilage, in others by Membrane. The Genera -Cyprinus and Gadus have, at the Nasal extremity of the Nerve, a spherical Gan- glion, composed in part of Cineritious Substance. The Optic Nerves, in the generality of Fislres, par- ticularly in those of the Osseous kind, cross each other without being incorporated. They are attached merely by Cellular Substance, the Right Nerve going to the Left Eye, and the Left Nerve to the Right Eye. In some Fishes, they are Fibrous ; in others, they have a laminated or plaited appearance. The Third and Fourth Pairs ar6 dispersed nearly as in the former classes of Animals. The Fifth comes off from Tubercles behind the Cerebellum, which, in the Jlaja 9 are remarkable for their great size. Each di- vides into three Branches, as well as in the Human Body ; and these go to the outer part of the Nose, tq the sides of the Mouth, and to the Face m general. Iri .] OF FISHES. 27S In the $lcate y the third Branch vanishes suddenly upon the Mucous Ducts which issue, as from a centre, at the outer and back part of the Eye. The Sixth Pair is distri- buted as in other red-blooded Animals. Of the Seventh Pair, the Portio Dura is large in Cartilaginous Fishes, and comes off from the Brain quite distinct from the Au- ditory Nerve. The Portio Mollis lies so near the Fifth Pair, as to appear to be a Branch of that Nerve. In Car- tilaginous Fishes, as the Skate, it passes into the Ear by a single Foramen ; in the Osseous kind, as the Cod 9 where the Ear is in the same Cavity with the Brain, the Nerve is dispersed directly upon that Organ. The "Eighth Pair is remarkable on account of its great size, and its distribution. It is divided into three portions, one of which runs directly to the Branchiae. The se- cond goes to the Muscles of the Tongue, and to the Esophagus. The third is a large Nerve, which extends under the Skin as far as the Tail Fin, upon which it terminates. A Nerve analogous to the Ninth Pair ap- pears to be wanting. The Great Sympathetic Nerve is also found here, but extremely slender. It unites with the Vertebral Nerves, but this, like the other Nerves of Fishes, has no visible Ganglia, excepting those in the Olfactory Pair in certain Fishes, as the Gadus, &c. The Spinal Marrow, in the Animals of this class, is re- markable for its great size when compared with the Brain. The Cervical Nerves are few in number, and in some Animals there are none, the Vertebrae of the Neck, in such Fishes, being wanting. When present, they are Chiefly dispersed about the Throat and Pectoral Fin. There 74 OF THE B^RAIN, &c. [PART IV. There is no Diaphragmatic Nerve, though one of the .first Vertebral Nerves is spent upon the partition be- tween the f Cavity of the Branchiae and that of the Ab- domen. The Dorsal and Lumbar Nerves are all distri- buted in the Intercostal spaces. The Sacral and Cau- dal Nerves are not very distinct ; they are lost in the posterior part of the Body and the Tail Fin. Besides the Nerves mentioned above, it is here thought proper to take notice of those which belong, in certain Electrical Fishes, to that curious apparatus which performs the office of a Ley den Jar, or Electrical Battery. The Raja Torpedo, Gymnotus Electricus, and Silurus Electricus^ are the only Fishes in which Electri- cal Organs have been discovered ; though one Species of the Tetraodon, and one pf the Tricjiiurus, possess the same electric property. In the three first-named Ani- mals, the Electric Organ consists of Aponeu.ro.tic Cells, filled with a fluid like the Glaire of an Egg. Upon this substance large Nerves are .distributed; but the proportional size and the structure of the Cells, the ori- gin, number, and relative magnitude of the Nerves, vary in the three different Species. The Electrical Organ of the Torpedo bears a large proportion to the Body of the Animal, and is situate^ between the Head, the Branchiae, and great Cartilage of the Pectoral Fin in each side j or in that part from whence the Mucous Ducts issue as from a centre, on the back of the Skate. It extends in a perpendicular direction from the Dorsal to the Abdominal Skin. When the Integuments are raised, the Organ appears, consisting PART IV.] OF FISHES. consisting of some hundred pentagonal or hexagonal columns, closely compacted, and giving somewhat the appearance of a Honeycomb. The Columns are form- ed of transparent Lamina?, and are connected together by transverse Tendinous Fibres. They are divided by a great number of thin partitions placed over each other, jbut leaving small spaces between them, which s*re full of a glairy liquor. Minute Blood-vessels are dispersed upon this Organ. Its Nerves are of extra- prdinary size, and are furnished by four principal Branches. The first is the Inferior Maxillary, or third portion of the Fifth Pair, and corresponds with that, which, in the Back of the Skate, sends a very large Nerve to the origip of the Mucous Ducts. The other Nerves are from the Eighth Pair, and come to the E- lectrical Organ after supplying the Gills. The whole of this remarkable substance is found to correspond in its effects with those of an Electrical Ma- chine. The upper and under surfaces of the Animal are charged plus and minus, and the shock is given at the will of the Creature ; but differs from that coming from an Electrical Apparatus, in producing neither light nor sound. The Electrical Organ, in the Gymnotus, is more de- veloped than that of the Torpedo. It composes a great part of the thickness of the very large Tail, and ex- tends from within a little distance of the Head to the posterior extremity of the Animal. It is divided into four portions, called by MR HUNTER Great and Small Organs* The Great Organs are placed above the Small at 27* OF THE BRAIN, &c. [PART IV. at each side of the Tail, of which they form about two inferior thirds of the thickness, the Caudal Muscles composing the principal parts of the remaining third. Each of the Columns is intercepted by a great number of Laminae, forming the whole into so many Cells, xvhich are here of a rhomboidal form. They receive their principal Nerves from the Spinal Marrow ; some of less consideration coming from the Sympathetic Pair. Of the SiluruS) the Organ covers the greater part of the Body. It begins at the Head, and extends to near the Tail, and forms a thick Stratum anteriorly, but becomes thinner as it approaches the Caudal extremity. It re- ceives its Nerves from those parts of the Eighth Pair which extend, in other Fishes, along the lateral parts of the Body; but these are much smaller in proportion than in the Torpedo. OF THE EYE. rr* 1 HE Eye of the Animals of this class is proportionally larger than in the two former, that of the Cod greatly exceeding the size of the Human Eye. In Fishes, as in the Cetacea, while the posterior part of the Ball is convex, the anterior is quite flat, the water in which they live refracting the jays of light, and FART IV.] OF FISHES. 277 and supplying the place of the convexity of this part of the Eye. In some Fishes, as the Skate and Shark tribe, the Eye rests upon a stalk of Cartilage, or expands behind into a kind of Tubercle, which allows the Muscles to act with more advantage upon it. In other Fishes, it rests upon Gelatinous Matter in form of a Cone, contained in loose Cellular Substance. Fishes are destitute of Eye-lids j but, to defend this Organ from injury, the Tunica Adnata is stronger than in Mammalia and Birds, and passes immediately over it without forming any doubling. It may be separated readily from the Tunica Sclerotica and the Cornea. Upon the inner or back part of the Cornea is a delicate Membrane, termed Tunica Aquea, which incloses the Aqueous Humour at the fore part of the Eye ; this can also be easily separated. In some, as the Eel, the Tunica Adnata allows the Cornea to move behind it, in the manner it does in Serpents, &c. The Cornea is not so firmly connected to the Sclero- tic as in Mammalia; it is easily separated from the Sclerotis, which appears then open at the fore part of the Iris. Most Osseous Fishes, as the Salmon, Mackerel, &c. have, at each corner of the Orbit, a Vertical Veil 3 which covers a small part of the Eye. The Tunica Sclerotica is Cartilaginous, semi-trans- parent, and lined with a delicate Membrane, which is commonly of a black colour. Fishes have no Tapetum on the Choroid Coat, the inner $7* OF THE EYE [PART IV. inner Layer of which, or Tunica RUYSCHIANA, is blacky but in the Skate, Shark, &c. the bottom of the Eye is of a silver colour, from the Choroid Coat appearing through its inner lining, which is here transparent. The outer Layer of the Choroides, or proper Cho- roid Coat, is white or argent, and Vascular. From the inner Layer, a Vascular ; Funnel-shaped Membrane arises, the Campanula of HALLER, which goes to the Lens^ and has been considered as analogous to the Mar- supium of Birds. Between the two Layers of the Choroid Coat, in the Osseous Fishes, but not in the Skate and Shark kind, there is a Body, termed Corpus Glandulosum, or Glan~ dula Choroidea$ of a brilliant red colour. It is in form of a Horse-shoe, or, in some, approaches to a circle. It is considered either as Muscular, and serving to make the Eye accommodate itself to objects at different dis- tances, or Glandular, and secreting some of the Hu- mours. The Corpus Ciliare is indistinct, and Ciliary Pro- cesses are generally wanting in Fishes. The Iris is intimately connected with the Choroid Coat, and possesses brilliant colours in different Fishes. In \\\Q Skate, the upper part of the Iris has apalmated Process or Curtain, termed Operculum Pupillare, which the Animal occasionally lets down to cover the Pupil. Of the Humours of the Eye, the Aqueous is so small in quantity, as to be seen with difficulty, the deficiency R being supplied by a spherical Lens, and the denser ele- ment in which the Animal lives. The Lens is, besides, observed to be not only rounder, but also more dense than FART IV.] OF FISHES. than in Land Animals, the more completely to refract the rays of light coming from the water. It is remark- ably large in most Fishes, but the Vitreous Humour is proportionally small. The Optic Nerves, in Osseous Fishes, cross each other Without any intermixture of Medullary Sub- stance, and go to the opposite Eyes. The crossing is less apparent in the Cartilaginous kind. In the Skate, the Right Nerve passes through an opening in the Left. In general, the Body of the Nerve is Fibrous, as in other Animals ; but in some, as the Sword-fish, it is formed of Layers put together like a Fan, and inclosed in the Dura Mater. In many Fishes, as the Raja and Squalus, the Nerve, getting into the Eye, forms, as in Reptiles, a small Tu- bercle, from the edges of which grows the Retina ; but in others, as the Salmon , Herring, &c. the Nerve, as in Birds, after perforating the Choroid Coat, forms two white lines, which give origin to the Retina. The Retina has a peculiar appearance in Fishes, be- ing formed of two Layers, the external of which is Me- dullary, and the internal Fibrous. The Muscles, in this class of Animals, as in the for- mer, are six in number, four straight, and two oblique ; but both of the latter come from the anterior and under side of the Orbit. One is inserted at the under, the other at the upper part of the Eye, without the inter- vention of a Pulley, as in Mammalia. OF OF THE EAll [PART IV. OF THE EAR. I HE Organ qf Hearing^ in Fishes, is as distinct as in other Animals, and much greater in proportion than in Mammalia or Birds. Partaking of the growth of all the other parts, it increases in size, in proportion to the age and bulk of the Animal, The different parts of the Ear, in this class, are more Teadily traced than in the former, r^ot only on account of the size, but also the looseness and softness of the parts. The Ears are divided into two kinds, according as the Fishes are Cartilaginous or Osseous, the former possessing certain parts which are not found in the latter. Of the Cartilaginous Fishes, a large Skate is here taken as an example. A little before the joining of the ' Head and Spine, there are two Foramina, placed obliquely, and at a little distance from each other, capable of admitting a large Hog's bristle, which are the Mouths of the External Auditory Passages. These are detected by pressure, when a small quantity of a milky- like liquor is found to issue from them. Each Foramen leads to a winding Canal, or a kind of Concha, almost of a circular form, lying under the Skin, and containing some chalky fluid. The bottom of this is of a Funnel shape, and ends in PART IV.] OF FISHES. 281 in a narrow passage, or Meatus Auditorius Externus, which pierces the Cranium. This goes directly to a Sac belonging to the Labyrinth or Internal Ear, there being no Membrana Tympani in Fishes. The Labyrinth is situated at the back and outer part of the Brain-case, a little behind the Eye, and is found by cutting almost horizontally, but a little downwards and outwards, through the substance of the Cranium ; the Animal being supposed to be placed in the prone situation. Between the Labyrinth and Bruin-case, there is a distinct partition, which communicates only by the Meatus Auditorius and the passages for the Nerves. The Internal Ear consists of a Membranous Laby- rinth, contained in a Cartilaginous one, hollowed out in the substance of the Cranium. The Cartilaginous Labyrinth somewhat resembles the Membranous in form, and is composed of an An- trum; and three semicircular, or rather circular Canals, all of which are lined with a Perichondrium ; but the Cartilaginous parts greatly exceed the Membranous in size. At the inner side of this Cavity are the passages for the Nerves ; at the outer is a kind of Fenestra Ovalis., which is shut only by a Membrane covered by the Skin. The Membranous Labyrinth is formed of a large triangular Sac, slanting obliquely outwards and down- wards, and is analogous to the Sacculus Vestibuli in Mammalia. It has also three semicircular Canals, in each of which there is an Ampulla, more conspicuous than in most other Animals. VOL. IV. S The 282 OF THE EAR [PART IV. The Sac contains a transparent viscid fluid, and has a soft starchy or chalky-like substance placed in its bot- tom, the whole apparatus supplying the place of a Ves- tible and Cochlea. There is no Tympanum nor Eustachian Tube in this class of Animals. At the anterior part of this Sac,- there is a smaller one, compared to the Cochlea of Birds, and behind, there is another still smaller, each communicating with the large Sac, and filled with the same kind of glairy fluid and chalky substance. The Membranous semicircular Canals are something similar, in their texture and transparency, to the Capsule of the Crystalline Lens in Mammalia, and are filled with the same kind of glairy liquor as that found in the Sacs, but do not contain any of the Cretaceous matter. One of the Canals passes downwards and outwards, another outwards and backwards, and both approach to a vertical situation. The third is placed between the other two, and runs nearly in a horizontal direction. The anterior and middle Canals join into a common ohe f which communicates with the anterior small Sac by a short Tube. The posterior Canal opens into the large Sac by a Duct of considerable size, but has no direct communication with the other two Canals. The Membranous Labyrinth is suspended in the Cartilaginous one by Vessels and Nerves, and by Cellu- lar substance containing a watery fluid. Upon the Sacs and Ampullae of the Canals, large Nerves are dispersed, which belong to Trunks analo~ gous PART IV.] OF FISHES. 283 gous to the Fifth, and Portio Mollis of the Seventh Pair, but chiefly to the latter. When the Animal is laid in the supine situation, and the Cartilage, which, in the natural state, lies under the Ear, is properly separated, Branches of the Portio Mollis are observed to form Penicilli upon the Ampullae, and an intricate Plexus on the" Vestible, and small Sacs projecting from it, which are fully exhibited in Dn MONRO'S work on the Eye and Ear. In Osseous Fishes, the Organ of Hearing has a gene- ral similarity with that of the former kind, but differs in several particulars. No Meatus Externus has been found. The Internal Ear is inclosed in the same common Cavity with the Brain j the Bones at the sides of the Brain only form- ing some Processes, to which the Labyrinth is connect- ed by Cellular Substance and Vessels, and by some Os- seous and Cartilaginous bridles. In some parts, also, Membranes intervene, but no distinct partition. There is a Sac or Vestible of considerable size, simple in some, divided in others, containing a viscid fluid, and one, two, or three Cretaceous stones, the number va- rying according to the kind of Animal. The stones have a particular figure, are of various sizes, and are white and hard like Porcelain. They are suspended in the pulpy fluid by a beautiful Plexus of Nerves, and have been regarded by some as serving the same purpose with the Ossicula Auditus in Mam- malia. There are here, also, semicircular or circular Canals, the outer Osseous, the inner Membranous; and, as in S 2 Cartilaginous 284 OF THE EAR [PART IV. Cartilaginous Fishes, the outer set greatly exceed the inner in size. The length of the Osseous- Canals varies in different Fishes ; part of them forms a sort of pulley, over which the Membranous Canals pass. The Membranous Canals vary also in length, but have in general the same kind of communication with the Vestible, and with each other, and form the same kind of Ampullae, as in Fishes of the Cartilaginous kind. Nerves corresponding with those in the Skate are also dispersed upon the Sac and Ampullae; but the Nerves pass to the Labyrinth without perforating the Bones. OF THE 1 HE Organ of Smelling is extensive in Fishes, though it has no connection with the Organs of Respiration, and is supposed to be acute, being a principal means by which they are enabled to search for their Food. The Nostrils, in Osseous Fishes, are generally divid- ed by a cross Membrane, which gives the appearance of being double on each side. Some Muscular Fibres are found about the Nostrils, which admit of a small degree of dilatation or contraction occasionally, but the motion is not very evident, In PART IV.] OF FISHES. 285 In the Raja, Squalus, &c. among the Cartilaginous kind, the Nostrils communicate with the Mouth by a Chink of considerable magnitude. In Osseous Fishes, instead of turbinated Bones, there are numerous Membranous Laminae, running in a ra- -diated manner from a Tubercle at the bottom of the Nose; but in the Raja, Squalus, and several others, there is an elegant plaited Membrane, in place of Ossa Spongiosa. This is disposed in crescentic folds, some- what in a parallel direction to each ..other, and placed on each side of a principal Lamina, which extends from one end of the Nostril to the other. There is no Foramen Incisivum in Fishes, there be- ing, strictly speaking, no Nasal Cavity here. Upon the Laminae above mentioned in the Nose, the Branches of the Olfactory Nerves are expanded, sup- plying the whole internal surface of that Cavity, and there forming a Retina, as in the Eye $ but the Fila- ^nents are more distinct. OF THE TONGUE. J HE Tongue, in Fishes, is in general of such a firm Cartilaginous nature, that some have doubted how far it is to be considered as an Organ of Taste. The Skin covering it is commonly very thick, like that of *he rest of the Mouth. It exhibits no distinct Pa- S 3 pillae. 286 OF THE TONGUE [PART IV. pillae, but, in many Fishes, is so garnished with a kind of Teeth, as to appear to render the surface almost in?- sensible. it is generally supported, as in Birds, by an Os Lin- guale, or a Cartilage which also supports the Branchiae. This, in some, is small ; in the Conger, it runs the whole length of the Tongue. The Raja, Squalus, and Lamprey , can scarcely be said to have a Tongue, the parts being quite smooth and even. Salivary Glands. Fishes in general are destitute of Salivary Glands. In the Carp, there is an irritable Glandular Body, situated on the Palate, and consider- ed by some Authors as supplying the want of these ; by others, it is looked upon as a sort of Tongue. In the Raja and Squalus, there is a mass of small Granu- lous Glands upon the Membrane of the Palate, which have been considered as analogous to th.e Mucous Glands in other Animals, OF THE HEART AND BLOOD- VESSELS. 1 HE Heart of Fishes is situated in a Cavity between the posterior parts of the right and left sets of Gills, and is small in proportion to the Body of the Ani- mal. The Pericardium, in many Fishes, is merely the lining of the Thoracic Cavity. The Heart, as in Frogs, IV.] OF FISHES. 287 frogs, consists of a single Auricle and a Ventricle, which correspond with the right side of the Heart of warm-blooded Animals. The -Auricle is common- ly larger than the Ventricle, but thinner in its walk. It receives the Blood from the Body, and sends it to the Ventricle, in the Mouth of which there are Valves, which vary in number in different Fishes. The Ventricle is sometimes round, at other times tri- angular, but more frequently of a tetragonal form. Its sides are generally remarkably thick, and .have Colum- nar Carneae running in different directions. It opens first into a Bulb or Pedicle, which is very conspicuous in the Cod and Salmon, where it is of a pyramidal form. In the Skate, it has a cylindrical appearance. In this Animal and the Sturgeon^ there aye Valves at the entry.,' and also at the further extremity of the Pedicle. In the Cod, Salmen, &c. the Valves are only at its origin. Principal Blood-vessels. The distribution of the Blood-vessels differs considerably from that of the Animals of the preceding classes. They have a smaller proportion of red, but a much greater num- ber of colourless Vessels. The Branchial Artery is continued from the Pedicle, and is entirely spent upon the Gills. In the Skate, it advances under the Cartilage which unites the inferior extremities of the Branchial Arches, and soon gives off a Branch to each side, that subdivides into three others, to be dispersed upon a corresponding number of Posterior Branchiae. The Trunk afterwards proceeds till it gets opposite to the two Anterior Branchiae, and then divides into a S 4 couple 288 OF THE HEART, &c. [PART IV. couple of Branches, which are distributed upon these Organs. In other Fishes, as the Cod, Salmon, &c. this Artery sends off Branches in a similar manner, but only four in number in each side, corresponding with the num- ber of the Branchiae. From the Gills the Blood returns, and is sent to all the parts of the Body by a set of Aricrious Veins 9 or Branches, which are found to be of the same thickness and strength with those of the Branchial Artery. In the Skate tribe, these Vessels, in number equal to that of the Gills, pass back under the Cartilage of the Neck, and join their fellows of the opposite side, to form the Aorta. Before they unite, they give Branches to the Keck, Head, &c. and furnish the Coronary Arteries of the Heart. The beginning of the Aorta sends a large Artery to each of the Lateral Fins, and parts adjacent, and soon after, the Cceliac and two Mesenteries to the Chylo- poietic and Assistant Chylopoietic Viscera 5 then Arte- ries to the Organs of Urine and Generation, and two large Branches to the Posterior Fins. The continua- tion of the Aorta goes at last to the Tail, protected in a Canal in the inferior part of the Vertebra?. In other Fishes, the Aorta is formed by only four Branches on each side, corresponding with the number of the Gills. In some Fishes, as the Sturgeon, the Aorta is almost entirely concealed in a Canal in the Bodies of the Vertebra?. Veins. The Veins, in this class of Animals, are ex- tremely thin in their Coats. They form receptacles for the Blood PART IV.] OF FISHES. 289 Blood, being much larger in their course, than at their termination in the Heart. At the opening of some of the Veins in the Heart, or where Branches end in some of the principal Trunks, there are a sort of Valves, which prevent the retrograde motion of the Blood. From the different parts of the Body, the Blood is returned to the Heart by one or two Posterior Cavae, si- tuated at the sides of the Aorta, by the Hepatic Vein, am} by two Anterior Cavse, one at each side of the Breast. OF THE ABSORBENT VESSELS. i I HE Mouths of the Absorbents, in Fishes, contrary to what is found in other Animals, can in some measure be seen, especially in some of the Raja, as the Skate. If a coloured fine injection be thrown into one of the principal Trunks, it passes out by numerous streams, especially on the back of the Animal. The Absorbents, in this class of Animals, are some- what flat, and have the Appearance of having Joints or Valves ; but no real Valves are found in any part of them, excepting at their termination in the red Veins, for an injection can be made readily to pass from the Trunks to the extreme Branches. They are also quite destitute of Conglobate Glands, and the Lacteals con- tain transparent Chyle. Itt OF THE HEART, fcc. [PART IV. In the Skate kind, the Absorbents are proportionally much larger, compared with their Blood-vessels, than in the former classes. They have frequent communications with each other, and often by transverse Canals ; but in place of form- ing- Thoracic Ducts, they unite into Right and Left Plexus, which go to the corresponding sides of the Body. The principal Absorbents of the Chylopoietic Viscera run near the large Branches of the Coeliac and Meseni- teric Blood-vessels, and the principal Lymphatics of the Assistant Chylopoietic Viscera attend the larger Ves- sels belonging to these parts,. Besides the Plexus these form, there is one of a sin- gular nature on the Curvature of the Stomach ; it has a Cellular or Cavernous appearance, which does not occur in any other part of the Body. Into the Visceral Plexus all the other Absorbents of the Body pass ; the Lymphatics of the inferior parts, and of the Organs of Urine and Generation, run up to them. Those of the Trunk go inwards, and those of the Head, Heart, and Gills, form chiefly a single Trunk, which descends. From these Plexus, a Trunk in each side of the Body ends in the Subclavian Vein at the joining with the Internal Jugular, where the fluids are prevented from returning by a pair of Valves. In the Cody Salmon, and other Osseous Fishes, there are five principal Vessels, which are more conspicuous than the rest ; one runs directly along the middle of the Belly, from the Anus to the Head, and receives the Lymphatics from the parts of the Body near it ; another along PART IV.] OF FISHES. 291 along each side of the Fish, near the great Mucous Duct, and belongs to the Body and Tail. One, deep-seated, belongs to the parts about the Spine and upper portion of the Head, and receives Branches from the Dorsal Fins and parts of the Back ; and a large Vessel, or Plexus of Vessels, belongs to the Gills, Mouth, Brain, and Organs of the Senses. The principal Lacteals run in the Mesentery, near the Arteries, communicating there by innumerable trans- verse Canals, but are smaller in proportion to the Blood-vessels than in the former tribe of Fishes. At the anterior part of the Abdomen, the Lympha- tics of the Stomach and Assistant Chylopoietic Viscera are added to the Lacteals. The conjoined Vessels pass to a large Reservoir at the right side of the posterior extremity of the Esophagus. From this Reservoir, large Absorbents, sometimes considered as analogous to Tho- racic Ducts, go forwards^ receiving, in their course, the Lymphatics of the Organs of Urine and Generation, and run into a large Cellular Receptacle on each side, situated chiefly between the Cartilage analogous to the Clavicle, and the undermost GilL These Receptacles receive also the Lymph from the five principal Vessels mentioned above, and from the various other parts of the Body. The two Receptacles communicate together by cross Canals, which run principally behind the Heart and Esophagus. In the Salmon, each Receptacle sends out a Duct, which terminates in the anterior extremity of the Pos- terior Cava of that side, at the fore and outer part of the Internal Jugular Vein. At OF THE ABSORBENTS [PART IV. At the termination of the Ducts are doubled Mem- branes, answering the purpose of Valves. In the Cod, the Receptacles contain the Muscles of the Gills, their Nerves, and the Cornua Anteriora of the Air Vesicles. OF THE ORGANS OF RESPIRATION. JNSTEAD of Lungs, Fishes are furnished with Bran- chiae, or Gills, or a kind of inverted Lungs, placed behind the Head, and communicating with the Throat. There are, in most Fishes, four Gills in each side, resting on an equal number of arched portions of Car- tilage or Bone, connected to the Os Hyoides ; and these are fixed to the Head, or to the first Vertebrae. Each of the Gills consists of two ranges of Cartila- ginous Laminae, and are joined together for two-thirds of their inner edge. The Laminae issue like rays, and have the Branches of the Pulmonary Artery minutely dispersed upon them* In many Cartilaginous Fishes, as the Raja, Squalus, &c. there are five Gills on each side In the Lamprey are seven. In a small Animal, the Hippopotamus, eight. In the first set of Cartilaginous Fishes, as the Skate, &c. there are, on the inferior surface of the Ani- mal, Holes equal to the number of the Gills, and on the Dorsal side, an opening behind each Eye ; but in the other kinds, there is only a single opening exter- nal]? PART IV.] OF FISHES. 295 nally from the Gills on each side, (an Apertura Bran- chialis), and this is covered by a moveable Gill-flap, (an Operculum Branchialis), which can more outwards or inwards at the will of the'Animal. After the water has been received by the Mouth, from this it is sent to the Gills, which expand, by the action of Muscles peculiar to them, in such a manner as to have it freely applied to their surface ; in conse- quence of which, Fishes derive Oxygen from water, as breathing Animals do from the Air in their Lungs. But the water does not return by the Mouth ; it is dis- charged by the Branchial openings, in which case Fishes differ from the former class, in not expiring through the same passage by which they inspire. OF THE ALIMENTARY CANAL. THE Peritoneum in Fishes is similar to that in Mam- malia, but is sometimes of a black colour, though often argentine. In the Skate tribe, it is not a shut Sac, as in Mammalia. It communicates by two Holes exter- nally, one at each side of the Anus, by which secreted Liquors seem to escape from the cavity of the Abdomen, but a kind of Valve appears to prevent the surrounding element from entering. The Diaphragm forms on Fishes a distinct partition between the Thorax and Ab* domen, but is purely Membranous. The 23* OF THE ALIMENTARY CANAL [PART IV. The Alimentary Canal is generally very short in this class of Animals, and seldom makes more than one, two, or three turns. In the Pipe Fish, Lamprey, Trunk Fish , and many others, it extends almost straight from the .Mouth to the Anus. In some there is very little dis- tinction into Stomach and Intestines, but internally the difference is generally marked by the structure, by the Pylorus, and by the Valve of the Colon. In many of the class, the Esophagus is so short and wide as scarcely to be distinguished from the Stomach ; and the Food is frequently found remaining partly in the Esophagus till that in the Stomach is digested. In the Branchiostegi, there is great difference in the form and structure of the inside of the Esophagus. It is beset with strong Combs or Tufts forming a fine Net- work, which distinguishes it from the Stomach. The Stomach of Animals of this class is generally long, and frequently found full of Fishes retaining their natural form, but quite pulpy, digestion being consider- ed to be chiefly effected here by solution. In the Squalus kind, there are numerous large Plicae jn the Stomach, running in a longitudinal, or in a transverse direction, or in both. In the Mullet, the Stomach is so rough within, that the Animal is enabled to ruminate> and hence is ranked one of the Spurious lluminants. The Intestines, in this class, vary still more than in the former, particularly with respect to the distinction between small and great. ' Sometimes the diameter of the two is the same, though differing in structure. Sometimes the difference in size is inverted, the upper being PART IV.] OF FISHES. 295 being larger than the under portion of the Canal. Sometimes the Coats of the upper are thicker than those of the under part of the Gut. In the greater number of Cartilaginous Fishes, as the Raja and Squalus, where the Canal is remarkably short, but is considerably dilated near the Stomach, the surface of the Gut internally is extended by longi- tudinal Spiral Valves. In the Sturgeon, the inner side of the Intestine forms a curious laminated Plexus and Fossula, which are co- vered with small Glands. In the Frog^fish and Sea- Wolf) there is a lozenged appearance. In the Turbot, the inner side of the Gut has many fringed Laminae. In the Skate tribe, there is a kind of Caecum, or Ap- pendix Vermiformis, between the small and great In- testines, but none in Fishes with Osseous Skeletons. In these the Gut is surrounded, at its origin, by small blind Appendices, or Intestinula Caeca, which open into it. They are sometimes long and slender, at other times thick and short, or simple, or ramified ; the number varying from 1 to 150 and upwards, and even in different Species of the same Genus. They are found in all the Osseous Fishes, with few exceptions, as the Pike, and secrete a fluid useful in digestion. In Cartilaginous Fishes, as the Skate, in place of these, there is a Glandular Body, which has been coni- pared to the Pancreas of warm-blooded Animals. The Intestines, in Fishes strictly so called, terminate in a common Cloaca, situated near the middle of the inferior part of the Belly, or before th Anal Fin la 296 OF THE AIR-BA& [PART IV. In the jRajct) they terminate near the middle of the under and posterior part of the Body ; and in this, as well as in the Squalus, it gives passage to the Faeces, Semen, and Ova. OF THE AIR-BAG. I HE Air-bag is situated between the Mesentery and the Spine, to which it adheres, in some through its whole length, in others only partially. It is very variable in form in different Genera and Species. It is commonly simple, as in the Salmon and Cod ; double, as in the Cyprius ; in others long, round, or oval. It consists of two Membranes, the outer of which is regarded by some as Muscular, and is covered partially by the Peritoneum. In the Cod, and also in the Sea Perch, a pair of Muscles run along the sides of the Air-bag, and these are assisted in their action by the great Lateral Muscles upon the Bodies of Fishes, It contains a quantity of air, differing in its nature in different Fishes. Nitrogen, with a small por- tion of Carbonic Acid Gas, has been found in the Carp, Hydrogen in the Tench, and Oxygen in the Shark. By the contraction of the Air-bag, whether by the action of its own Coats, or of the Lateral Muscles of the PART IV.] OF FISHES. 297 the Body, the contained Air is considered to be con- densed, by which the Animal can sink ; or, by a relax- ation of these parts, the Bag can be dilated, so as to allow the Fish to rise again at pleasure. The Cavi- ty of the Air-bag is commonly uniform, but sometimes divided by Septa, as in the Silurns, or Cellular, as in the Porcupine Fish. Its sides also vary much in thick- ness and strength in different Fishes. Upon the inner side of this Sac, in the different Species of Gadus, as Cod, Haddock, &c, a Gland is situated, which has a lobulated structure ; and in the Eel, there are two, from which the contained Air is supposed to be secreted. In the Sea Perch, there is also a Gland, but, besides this, there are two others on the outside of the Bag, from which numerous Vessels containing Air arise, and unite into a Trunk that opens into the Sac. In other Fishes, no similar Organs arc found, but Vessels are observed on the inside of the Sac, which seem to secrete Air to answer the same purpose. The Air-bag generally communicates by one, and sometimes by more Ducts of various lengths, with the middle part of the Esophagus, or of the Stomach, though more frequently with the former. Sometimes, as in the Herring, it ends in the bottom of the Stomach. In some, as the Sturgeon, it communicates with the Sto- mach without the intervention of a Tube ; and here, as also in the Salmon, there is a Sphincter Muscle, which may act as a Valve. Where a Sphincter is not found, the Muscular Fibres of the Organ in which the VOL. IV. T Tube OF THE AIR-BAG [PART IV. i Tube terminates, are considered as answering the same purpose. In the Cod and Haddock, there are no openings, but they have two long blind Processes, which terminate at the Fauces. The presence or absence of the Air-bag in Fishes is extremely variable. It exists in some Species of the same Genus, and not in others, and is considered, therefore, as an Accessory Organ of Motion, the ab- sence of which can be supplied by other means. It is more generally present, and largest, in those of a long and roundish form, as the Cod, Salmon, &c. and these swim with the greatest velocity ; but when the Bag is punctured, or otherwise ruptured, the Animal imme- diately sinks to the bottom. Dead Fishes, on the other hand, where the Bag remains entire, float on the surface of the water, an additional quantity of Air being probably generated by putrefaction, and their Bodies thereby rendered lighter. The Air-bag is for the most part wanting in flat Fishes, as the SJcate, Sole, &c. their broad surface and side Fins compensating for the want of this Organ ; but these Animals can only swim at the bottom of the water. It is wanting, also, in the Shark tribe, but the want is supplied by the great strength of the Tail. The Lam- prey has none, and though many of the Eel tribe have a small one, these Animals are kept down by the weight of the Tail. OF PART IV.] OF FISHES. 299 OF THE LIFER, 1 HE Liver, in many of the Animals of this class, is remarkably large in proportion. It lies chiefly in the left side, and in some, as the Skate and Cod, contains a great quantity of Oil, though these Animals, as well as Fishes in general, are destitute of Fat. The Colour is a whitish yellow, or rather grey. It varies in the number of its Lobes, often in different Species of the same Genus, and is extremely tender in its consistence. There is frequently, as in the Lamprey, only one Lobe ; sometimes two, as in the Sturgeon ; or two or three, as in the Cod, and here they are of great length. The Skate has three, and these extend to near the posterior extremity of the Abdomen. The situation of the Gall- Bladder is more variable in Fishes than in the Animals of the former classes. In some, it adheres to the surface of the Liver ; in others, as the Skate kind, a great part of it is concealed in the substance of this Organ. In some, as the Cod, it is at a distance from it. It is wanting in several Fishes, as the Lamprey, the Lump, and certain Species of Perch. In some it is placed horizontally, in others obliquely, and in some it has a transverse direction. The Biliary Ducts, in Fishes, as in Fowls, open se- parately into the Intestine, and here also are distinct Hepato- Cystic Ducts. These go commonly in succes- T 2 sion 300 OF THE LIVER, &c. [PART IV. sion into some part of the Gall-Bladder or its Duct, or into both at the same time. The Hepato-Cystic Ducts are commonly short, which facilitates the motion of the Bile. In the Turbot, Cat-Jish, &c. these Ducts are nu- merous, and go into the Gall- Bladder. In the Eel, Sole, Perch, and many others, they go in succession into the Cystic Duct. In the Skate, Salmon, &c. they go partly to the Gall-bladder, and partly to the Cystic Duct. Pancreas. In Osseous Fishes, there is no other Pan- creas than the Intestinula Caeca formerly described. They send two large Canals into the Intestines, and when these are wanting, as is the case in the Carp, &c. the walls of the Intestines discharge abundance of Hu- mour from Glands placed upon their inner surface. In Cartilaginous Fishes, as the Skate, there is a Pancreas resembling that in the former classes of Ani- mals. It is of an irregular form, and is placed at the origin of the Intestines. The substance appears com- pact, but Gelatinous, when cut. In the Sturgeon, the Pancreas forms a sort of medium between that in the Skate and the Intestinula Caeca in the Osseous Fishes ; it opens into the Intestine by three large Orifices, and has internally a singular reticulated appearance. Spleen. The Spleen gradually diminishes in propor- tional size from Mammalia to Fishes. In the Raja and Squalus, it is placed on the Stomach ; in some it is fixed to the first part of the Intestines , in others, between the Stomach and Liver ; in a great number, it is under the Air-bag, and above the other Bowels : In all, it is fixed in its place by the Peritoneum. It varies consi- derably PART IV.] OF FISHES. 301 derably in its form here, as well as in the Animals of the former class. In the Raja, Squalus, and Sturgeon it is almost triangular; in others, angular, spherical, &c. In some it is remarkable for its length. OF THE URINARY ORGANS. A 1 ISHES in general have Kidneys ; some have a Bladder of Urine, and others want it. The Kidneys are large in proportion, but smaller in the Raja and Squalus than in other Fishes. In the greater number they are long, narrow, and united apparently into one mass. They adhere to the Spine from the posterior part of the Ab- domen to near the Orbits, and have the Peritoneum extended over their under surface. They are uniform in their substance, soft, and of a reddish brown colour. Renal Glands are wanting in this class. The Ureters begin by numerous roots, and run along the under surface of the Kidneys. They terminate ei- ther in a Vesica Urinaria or a Cloaca j or unite together to form a dilatation, which supplies the place of a Blad- der of Urine. The Urinary Bladder is very variable here. It is wanting in the Raja and Squalus ; in these the Ureters end in a Cloaca, as in Birds. In other Cartilaginous Fishes, it is present, but is proportionally small, and is T 3 thin 302 OF THE URINARY ORGANS [PART IV. thin in its Coats. It is remarkable in receiving the Ure- ters at its Fundus or anterior part. The Urethra is short, and commonly opens behind the Anus by an orifice, which also gives issue to the Semen in the Male, and Ova in the Female. In most Osseous Fishes, the Ureters, near their termination, form a large dilatation, which opens externally by an orifice generally behind the Anus, which also gives pas- sage to the sexual evacuations. OF THE MALE ORGANS OF GENE- RATION. THE Testes, in Fishes, on account of a difference of structure, are divided into two kinds, viz. 1. Those of the Raja and Squalus in the Cartilaginous Fishes, and, 2. Those of the other part of the Cartilaginous Fishes, and all the Osseous kind. The Testes of the first kind are analogous to those in the Frog. They are flat and of great extent, are situated between the Spine and the Stomach and Intes- tines. Each is divided into a large and small portion. The first is a mass of spherical Glandular Bodies, which, in a common-sized Skate, arc nearly as large as Peas, and press against each other, being intimately con- nected PART IV.] OF FISHES, 303 nected together, and covered by a delicate Membrane* The other portion is formed of a uniform Glandular Substance, something like the soft Row or Milt of Os- seous Fishes, The Epididymis, here, is also of great size, and formed of a large Canal making innumerable convolu- tions, From this goes out a Vas Deferens, which runs along the edge of the corresponding Kidney in a zig-zag manner ; increasing in size till it terminates in a Vesi- cula Seminalis near the Anus. At the outer side of the Vesicula Seminalis, is a Bag .filled with a greenish matter, which 5& discharged into the Sac for receiving the Semen. By some Authors, this Bag is considered as a Vesicula Seminalis. j by DR MONRO, as supplying the place of a Prostate Gland*. In some other Cartilaginous Fishes, as the Torpedo^ the Vas Deferens and the Vesicula open into the Cloaca by means of a Papilla, the Penis being absent here, as well a& in all the other Animals of the Class. In the other kind, or Roe Fi&hes y the Testes hold nearly the same situation as in the Raja and Squalus^ and are large Glandule-membranous Sacs; in some Cylindrical, in others Conical, &c. The size increases greatly at the spawning- season ; at other times, they can scarcely be distinguished from the Roe. They are- filled with a white Milky-like matter, the Semen, which appears to be deposited in cells. Through the middle of each Testicle passes a Vas Deferens, which unites with its fellow at the posterior part of the Abdomen, and opens by an. orifice com- T & xnon.lv SO* OF THE FEMALE ORGANS [PART IV. monly situated behind the Anus. In some, as the Carp, the Vas Delerens opens into a sort of Vesicula Seminalis, which terminates in the Cloaca. OF THE FEMALE ORGANS OF GE- NERATION. IN a part of the Cartilaginous Fishes, and in Osseous Fishes, excepting those of the Viviparous kind, the O- varia and Oviducts appear to be blended together, and the Ovaria seem to terminate directly upon the outer surface of the Body ; but in another part of the Carti- laginous and of the Osseous Fishes, the Ovaria and Oviducts are distinct from each other. In the Raja and Squalus, there are two Ovaria and two Oviducts. The anterior extremities of the Ovi- ducts are situated behind the Diaphragm, and united together, and also to the Spine. In the Skate, the O- viducts have one common opening at their origin. Each Duct passes backward and outward, and is of a cylindrical form, but of small diameter. Internally, it has longitudinal Plicss and Glandular Papillae, and leads to a large and thick Glandular substance, which is considered as secreting the Glaire of the Egg. It afterwards dilates into a large Sac, which is the Uterus, where the Egg receives its Shell, The Shell has a horny PART IV.] OF FISHES, 303 horny consistence and quadrangular form, with curved Spinouscorners, and is known by the name of Sea-mouse, In the Shark, this substance has a plaited appearance. The Uterus terminates at the sides of the Cloaca, while the Alimentary Canal ends at its under part. The Ovaria are situated at the sides of the Spine, and contain Ova of different sizes ; the smallest are of a white, and the largest of a yellow colour. They pass by degrees into the Oviducts, getting first the Albu* men, and then the Coraceous Shell. The Ova bear a strong resemblance to the Yolks in Birds ; but Fishes of this kind hatch the Eggs in the Abdomen, and after- wards bring forth the young. While the Fcetal Skate lies in the Shell, upon opening this substance while perfectly recent, the Animal can be seen moving in the fluid in which it swims. There is likewise observed at this period, a short Tube, which conveys the Yolk to the Intestines, as in Birds. In the Shark, from 20 to 50 Foetuses have been found, laid regularly by the sides of each other, in the Cavity of the Uterus. Oviparous Bony Fishes. -The Female Organs of Ge- neration, in these, consist of two Bags containing the Ova, and termed the Hoe. The Ova are small and ex- tremely numerous, upwards of 60,000 having been counted in a Perch weighing little more than a pound ; and in some other Fishes, more than 200,000 have been found. The Bag containing them is situated, as the Testes are in the Male, at the sides of the Spine, and are two delicate Membranes, which extend in the Abdomen as far as the Anus j occupying, near spawn- ing-time, 306 OF THE FEMALE ORGANS. [PART IV. ing-time, a great part of the Belly. The Ova are ge- nerally disposed in transverse layers, and connected by Blood-vessels. The common exit is behind the Anus, without the intervention of an Oviduct. In many Fishes^ the Ova or Spawn of the Female is observed to be first disch;f|ged, after which the Semen i& ejected from the Male, ^nd scattered over the Spawn 5 the fecundation of these Animals being external* PART PART V. OF M O L L U S C A, I HE Mollusca, like other Intervertebral Animals, are destitute of a real Skeleton ; but many have dis- tinct Jaws, which are fixed in the Flesh, there being no Head for articulation. In the Cuttle- Fish) there are two horny Jaws, like the Bill of a Parrot, situated in the centre of the fore part of the Body, and serving for the trituration of the Shell-fish which the Animal devours. Surrounding the Jaws are the Tentacula, or Large Arms, which, by means of numerous cups placed upon them, enable the Animal to fix itself to surround- ing objects. Some of the individuals of this class, as the Snail, have but one Upper Jaw ; others have two Lateral Jaws. The Tritonia has two Jaws, which act like the blades of Scissars j but many have none. In some, as the Whelk, &c. a Proboscis supplies the place of Jaws. In the back of the Cuttle-Fish, there is a kind of Bone composed of Lamella?. In other Spe- cies, its appearance is different ; but it is generally elas- tic and transparent. The Sepia Octopus wants it. The Epidermis, in this class of Animals, varies in thickness in different individuals. In Testaceous Mol- lusca, SOS OF MOLLUSCA. [PART V. lusca, it covers the Shell on both sides, and may be readily separated from it by means of diluted acids. Most of this class produce a viscid liquor, which lubri- cates the Skin. In the Mollusca Testacea, the Shell is formed in a peculiar viscous substance, the Sacculus Calcareus of SWAMMERDAM. The Muscles agree, in many particulars, with those of the Animals of the former class. In the Mollusca Cephalopoda, the Sac which composes the body is form- ed of a Muscular substance, divided into Layers, fitted for moulding the Animal into various forms. Two strong Muscles arise from each side of the Sac inter- nally, and are fixed to the Head. The Tentacula round the Mouth have Muscles, some for acting directly upon them, others proper to the Suckers placed upon these bodies. The first set enable the Animal to move the Tentacula in every direction, the second contract the cups from a flat to a hollow surface ; and by forming a kind of vacuum within them, enable the Animal to fix itself firmly to surrounding objects. The Muscles of locomotion, in the Gasteropoda, .reside in the under part of their body, which serves them at once as a f. ort of belly and foot. It consists of fleshy fibres running variously, by which it can contract a part or the whole of the Body at the same time, as may be readily perceived in the Slug or common Snail. In the Gasteropoda, as the Snail or Limpet, there are additional Muscles arising from the inner surface, or from the edge of the Shell, by which the Animal can protrude from, or retire into its covering. The Accphala, as the Oyster-^ Muscle, &c. have a covering principally com- posed PART V.] OF MOLLUSCA. 309 posed of a membrane-muscular substance, termed Cloak. This, in the greater part of the Species, is covered by Shells of various forms, and furnished with complete hinges. These hinges are connected by Ligaments placed in different parts of the Shell according to the kind, and of such an elastic nature as to have a constant tendency to open the Shell. The Cloak varies much in the dif- ferent Genera. Most frequently it is open before, as in. the Oyster, Muscle, &c. Sometimes it is perforated at both extremities, as in the Razor-shell, &c. The Cloak of the Oyster is formed, like the Shell, of two pieces fixed next the hinge, and has a semi-transparent ap- pearance. The pieces are perforated by the Muscle which closes the Shell. The opening which receives the nourishment, and that for discharging the Faeces, are formed by the Cloak, and these are sometimes pro- longed into a Proboscis. In the Oyster and Muscle, there is only one of these openings, which is the Anus ; the nourishment entering by a slit in the Cloak. The Valves of the Shells are closed by one or two Muscles, according to the shape of the part. In the Oyster, and others of a similar form, there is only a single Muscle, but of great strength. It is situated near the centre of the Shell, and behind the Liver. It is fixed firmly to both portions of the Shell, and shuts them with great force; the elastic Ligament at the hinge acts as an antagonist, by opening the Shell. In the Muscle, Cockle, Razor-shell, &c. there are two Muscles for shutting the Shell, and they are placed near the hinge. Many Acephalous Mollusca have a locomotive power, in 310 OF MOLLUSCA, [PARTY, in consequence of a Muscular Appendix or Foot, hav- ing on each side a set of Fibres like Silk. This Body they can protrude or retract, so as to fix themselves to solid substances, or drag themselves along the sand. This substance is termed the Beard, and is exemplified in the Fresh-water Muscle, where it is situated under and near the fore part of the Shell. By means of the Beard, the Animal has sometimes been observed to move to the distance of some yards in a few hours. The Oyster, Scallop, and several others with unequal Shells, have no Foot, and are therefore deprived of lo- comotion. In the Razor-shell, the Foot is of such a nature as to enable the Animal to come to the surface, orbury itself in the sand, with great rapidity. In the com- mon Cockle, the Foot is shaped like a Tongue, and is mov- ed by several Muscles on each side, being employed both in spinning and crawling. The former of these func- tions is performed by seizing, with its point, the Gluten which is furnished by a Gland situated at its base. It draws this out into threads, and, while still soft, it at- taches them to the rock, &c. to which the Animal is to be fixed. The Nervous System exists in most of the Animals of this class, and consists of a Brain placed upon the Eso- phagus, and of Nerves. In the Sepia, the Brain is contained in a Cartilaginous Covering belonging to the Head,, and has connected with it a kind of Medullary Collar, inclosed in a semicircular Canal, which gives passage to the Esophagus. From the Collar, Nerves are sent off to the different parts of the Body. Some of considerable size go to the Tentacula ; two Optic Nerves perforate PARTY.] OF MOLLUSCA. Sll perforate the Sclerotis, and swell out into large Ganglia, from which Fibrillae go through the Choroides to form the Retina. A pair of Nerves belong to the Muscles of the Sac, and another to the Organ of Hearing. A pair near the Heart forms a Plexus, which supplies the dif- ferent Viscera. In the Sepia Loligo, the Brain consists of a small round Body, behind which are two little Lobes analogous to the Cerebellum. These send off a mere Filament in place of a Spinal Marrow. On each side of the Brain is a large mass, which sends off the Optic Nerve. In the Snail and Slug y the Brain is situated, in the former over, and in the latter behind, the Esopha- gus, and sends off a Process on each side of it, both u- niting below into a large Ganglion, from which and the Brain, Nerves are sent to the different parts of the Body. Eye. The Sepia alone of this class of Animals possess- es true Eyes. Here we observe their great size, and the Skin covering them loosely as in Serpents ; a transpa- rent Membrane underneath, which supplies the place of a Cornea, and to which the Lens is closely connected without the intervention of an Aqueous Humour ; the Iris intimately connected to the Sclerotica, and a Semi- lunar Process projecting at the edge of the Pupil ; the Ciliary Processes large, and forming a Zone about the Lens ; between the Sclerotis and Choroid, Glandular Bodies and the Ganglion of the Optic Nerve, which se- parate these two Coats from each other ; the inner sur- face of the Choroides of a deep purple colour, and only two Muscles belonging to the Ball of the Eye, The parts considered as the Eye of Mollusca with Tentacula, or Horns, as in the Snail and Slug, are pla- ced 312 OF MOLLUSCA. [PART V. ced upon the outer extremities of the Horns, though it is not yet fully ascertained whether these parts are real organs of vision. The Muscles which affect them arise from the edges of the Foot of the Animal, and ex- tend as far as the Eyes. By these the Teutacula are drawn to the Head, something after the manner of an inverted Finger of a Glove. By a set of Circular Fibres contracthig in succession, the Eye is restored to its for- mer external appearance. The Organ of Hearing in the Cuttle-jish is a simple Bag, concealed in the Annular Cartilage at the base of the great Tentacula. In the Sepia Officinalis, the Sac has a Bone suspended in the Fluid it contains. In the Sepia Octopus, there is only a chalky substance. The Organ of Smell is supposed to belong to many of the Mollusca, but the situation is unknown. The Lips, in the Animals of this class, are in some short or real Lips ; in others, elongated into a Tube or Proboscis. In the Cephalopoda, they are in form of a fleshy circle ; in the Gasteropoda, they are merely a lon- gitudinal Slit. The Proboscis in many Mollusca, as the Whelk, &c. is a fleshy Tube for seizing the Food at a distance. It forms a kind of double cylinder, which can move in every direction, and retract within the Body. The Tongue varies much in length in some of this class, as the Limpet, where it is almost as long as the Body; but in such cases there is no Proboscis. In the Cephalopoda and Gasteropoda, the Tongue is covered with Spines directed backwards. The Sepia, Snails, and greater part of the Gasteropoda, have a Cartilagi- nous PART V.] OF MOLLUSCA. 315 nous Tongue. In the Acephala, a proper Tongue is not very evident. The Salivary Glands, in Cephalopoda and Gastero- poda, are considerable. In the former, there are two pairs, each having a Duct, which unites with its fellow, and opens into the Mouth near the Tongue ; the latter have commonly but one pair, which lies near the Mouth. Circulating System. In the Cephalopoda, the Circu- lating Organs are more complicated than in other Ani- mals. In the Cuttle Fish, there are three Hearts, two Pulmonary, and one Aortic. Each of the Pulmonary Hearts consistsof an Auricle and a Ventricle. The Aortic Heart has only a Ventricle. There are two Pulmonary Arteries, one to each Gill, and the same number of corresponding Veins ; an anterior and a posterior Aor- ta; and an anterior and two posterior Venae Cavae. At the openings of the Veins into the Hearts, of the Auricles into the Ventricles, and of these into the Ar- teries, Valves are placed to prevent the retrograde di- rection of the Blood* The Ventricles have also Colum- riae Carneaa, as in the former classes of Animals. The anterior Cava separates behind into two parts, each of which receives a posterior Cava, and terminates in an Auricle. Where the Veins meet at the Pulmona- ry Hearts, there is an intricate net-work of Columnar Carneae and Foveae. The Auricle opens into the Ven- tricle, which is placed at the root of a corresponding Gill. From the Ventricle the Branchial Artery is sent out, which runs along one side of the Gill, while the VOL. IV. U Vein OF MOLLUSCA. Vein returns by the other. The Branchial Vein termi- nates in the Aortic Ventricle, from the opposite ends of which the Aortse go out, sending Branches to the different parts of the Body, from the extremities of which the Veins return by the Venae Cavae. The other Mollusca have a simple Heart, consisting of an Auricle and a Ventricle. The Gasteropoda, as the Slug, Snail, Limpet, &c. have each also one Auricle and one Ventricle. The Veins of the Body, upon approaching tKe Lung, change into a Pulmonary Artery, in the manner the Vena Portas Abdominalis changes into the Porta Hepa- tica ; the Pulmonary Veins go to the Auricle, and this to the Ventricle, which sends, by an Aorta, Branches to the different parts of the Body. The Pulmonary System here is situated in the vicinity of the Rectum, by which the Vessels receive more readily the Veins of the Intestines. The Acephalous Mollusca, as the Muscle, and diffe- rent Concha Bivalves Equivalves, have the Heart near the Rectum. The Auricle receives the Blood from the Branchiae, and sends it to the Ventricle, whence it is transmitted to the Body. Organs of Respiration. These consist of Branchiae, which are either concealed or exposed. The Cephalo- poda and Acephala have them shut; the Gasteropoda have them in different situations. In the Cuttle Fish, the Lungs form two Conical Bodies, lying in each side of the Sheath, which incloses the Viscera of the Abdo- men. The Slug and Snail, among the Gasteropoda, have PART V.] OF MOLLUSCA. 315 have a Cavity in the Neck, which supplies the place of a Lung, and has the Pulmonary Vessels dispersed upon its surface. The Lung, in these Animals, terminates by a small orifice on the surface of the Body, which can be opened or shut at pleasure, and the Lung dilat- ing or contracting, can admit or expel the air. In the rest of the Gasteropoda, the orifice varies considerably in its situation, being in the back in some, in the breast in others. Some of the Acephalous Mollusca, as the Oyster, have their Lungs in form of Gills, which repre- sent leaves, each with a double Lamina, and a double Series of Vessels. Alimentary Canal. The Alimentary Canal, in Mol- lusca, consists, as in more perfect Animals, of an Eso- phagus, Stomach, and Intestines, but the beginning and termination of the Canal varies considerably in si- tuation in different individuals. In the Septa Octopus of the Mollusca Cephalopoda 9 the Esophagus, having passed the Cartilaginous Ring of the Neck, dilates into first, second, and third Stomachs, which somewhat re- semble those of Granivorous Birds. In the Sepia Offi- cinales and Loligo, there is only a single Stomach or Gizzard. In the Gasteropoda in general, the Canal is in form of a Funnel ; the most simple is in the Slug and Snail. The Stomach, in these, is of considerable size, and the Intestines make a couple of turns in their course through the Body. In many of the Mollusca, particularly among the Acephala, the Esophagus ex- pands into a Crop, which is covered internally by small Teeth, The Bulla Lignaria contains three Teeth of U 2 such 316 OF MOLLUSCA. [PARTY. such strength, that the Animal masticates other Testa- cea, upon which it lives. The Anus, in the Mollusca, varies considerably in situation among the different Ge- nera or Species. In the Cuttle Fish, it is at the fore part of the Neck ; in the Slug and Snail, close to the air-hole ; in the Limpet, it is upon the top of the Head ; and in the Acephala in general, opposed to the Mouth. The Liver, in the different Mollusca, is commonly large in proportion ; it has no Vena Portae ; it receives its Blood from the Aorta, and returns it by Veins to the Cava. In the Cephalopoda, the Liver is a brown mass, situated near the Head, and extending into the Abdomen. In the Sepia Loligo, the Bag which pro- duces the ink is situated on the Liver, and sends out a Duct, which terminates near the end of the Rectum. In the Sepia Officinalis, the Ink-bag is situated between the Lobes of the Lirer, and in the Sepia Octopus, at a distance from them. In these Animals, according to CUVIER, the Liver sends Bile of an orange colour, by two Ducts, into the Gizzard. The contents of the Ink- bag are supposed to be discharged by the action of the large Muscular Sheath of the Body of the Animal, and serve to render the surrounding element bitter, when the Creature is in danger of being attacked by an ene- 'iny. The Gasteropoda have a large Liver, divided into 'Lobes, which send out a number of Ducts that sur- round the Alimentary Canal, and terminate in the In- testines. In the Slu and Ex- crementitious Matter, pass through an Intundibulum placed under the Neck. In the Female, the Ova occu- py the same place as the Testicle in the Male, and are U 3 covered 318 OF MOLLUSCA. [PART V. covered also by a Capsule, and connected at one part by Vessels One or two Oviducts end at the Anus, or at the sides of the Branchiae, in the same place as the Penis does in the Male. This, as well as the other Species, has two large Glands, which are supposed to furnish a Gelatinous fluid, to surround the Ova. In the Gasteropodous Hermaphrodites, there is one set, as the Snail, and several others, where the Organs of the Sexes have a common outlet, and another, as the Jplysia, where they have a separate exit. The first set have a Testicle, a Vas Deferens, a Penis, and a Ve- sicle with a long Neck. The Testicle is a long white granulated Body, which sends out the Vas Deferens that terminates in the Penis, and this in a fleshy Sac, which is the common Cavity of Generation. The Ova- rium is composed of a cluster of Ova, situated between the Liver and Intestines. From the Ovarium an Ovi- duct goes out, which, about the season of sexual inter- course, makes zig-zag turns, and is so connected to the Testicle, as to appear to receive liquor from it. It ter- minates in the common Cavity of Generation. In time of copulation, the Snail tribe turn out the common Cavity, which then presents the three openings of the Penis, Oviduct, and Vesicle. The Penis pene- trates the Oviduct of the other individual. The Eggs are observed to be produced a few days afterwards. The same circumstances, in general, take place among the other individuals. Of the Gasteropoda with Sexes separate, the Male of the Buccinum Undatum is observed to have a Testicle, which, with the Liver, fills half of the deepest part of the PART V.] OF MOLLUSCA. S19 the Shell. The Vas Deferens forms numerous turns, and goes to the Penis, which is of great size. It ad- heres to the right side of the Neck, and folds in the Cavity of the Lungs. In the Female, the Oviduct is a great Canal at the right side of the Lungs, placed be- tween the Body and Rectum. The Acephala are found to be all Hermaphrodite. They fecundate themselves without copulation. An Ovarium is placed in both sides of the Body, directly under the Skin. At a certain period a white liquor ap- pears, which is considered as Semen. After the Ova are impregnated, they are situated between the Bran- chiae. In the Ovo- viviparous, as the Muscle, the young can he observed by the naked eye, and, if viewed with a Glass, can be seen opening and shutting the Shell. PART PART VI. OF CRUSTACEA 1 HE Body of the Animals of this class has a hard ex- ternal covering, frequently consisting of several scaly portions ; and they have often a considerable number of articulated members. They have several pairs of Organs supplying the place of Jaws, which move only in a lateral direction, the set on one side overlapping that on the other. They have one or two pairs of articulated moveable Bo- dies, termed Antenna, or Horns, placed on the Head, and two or three pairs of Palpi, or Feelers, articulated with the Jaws, for examining their nourishment. An Epidermis exists in this, as in other Inver- tebral Animals. The Shell holds the place of the Corpus Mucosum, but it is without organization. Un- der the Shell is a transparent Pellicle, instead of a Cutis. Muscles. Those of the Lobster and Crab have a con- siderable analogy to some of the Muscles of red-blood- ed FART VI.] OF CRUSTACEA. 321 ed Animals, but are confined to the parts moving the Tail, the Legs, and the False Feet. The Tail is a strong moveable substance, employed particularly in swimming and leaping, and has powerful Muscles for moving it in various directions. The Feet vary in number and form in the different Genera. In the Genus Cancer, as an example, there are commonly five Feet on each side, with six joints to each Foot. The anterior is the largest, and forms the Pincer or Claw. The first of the pieces of the anterior Foot, is the Coxa, which is connected to the Thorax ; the second the Femur, which *is nearly of a square form, and moves as a hinge on the Coxa ; the third is the Tibia, which, at the under extremity, becomes broad and Spinous ; the fourth is connected to the Tibia ; the fifth is the Pincer , strictly so called, which is the largest of the whole, and has opposed to it the sixth, which forms a moveable Pollex or Thumb. The other Feet are like the Pincer, but differ in this, that the two last pieces are nearly of equal size. The two posterior Feet terminate each in a single Claw. Each Articulation of the Feet has two Muscles, an Extensor and a Flexor, the strength varying according to the force required. Nervous System. This varies according to the form and nature of the Animal. In the Lobster, there is a Nervous Cord, which has a knotted appearance, and extends from one end of the Body to the other. The short-tailed Cancer, or Crab, has a Medullary Circle in the middle of the Abdomen, from which the Nerves of the Body go off like Radii. In the Cray Fish, the Brain 322 OF CRUSTACEA. [PART VI Brain is divided above into four Lobes, from which a pair of Optic Nerves are sent off. Four Nerves pass to the four Antennae and adjacent parts. From the pos- terior part of the Brain Nerves go off, which form a Collar round the Esophagus. The different Nerves form Ganglia, which' supply more particularly the seve- ral Muscles. In the Lofoter kind in general, the Eye is placed on a moveaWe Tubercle, and is somewhat conical. When magnified, it presents different Facets, which are hard and. transparent, representing so many Corneae. Lin- ing these, there is an opaque Pigment, which appears to leave no aperture for the passage of the light. At a little distance from the Corneas, is a dark coloured Membrane, considered as the Choroides, which has a production of the Optic Nerve on its posterior as well as its anterior surface, and therefore forming a sort of double Retina. But how the light can act upon the bottom of the Eye through the opaque lining of the Cornea, and whether these Animals, from the com- pound nature of their Eyes, see objects multiplied or single, are circumstances not understood. The Ear, in the Lobster, is a small Sac inclosed in a scaly cylinder. At the base of the Antennae, the Nerves pass through this cylinder into the Sac, the opposite ex- tremity of which is inclosed by an elastic Membrane analogous to the Membrana Tympani, or the Fenestra Ovalis, and is observed at the bottom of the large An- tennae. Organ of Smell. None is found in any of the Crus- tacea, though many Authors have been of opinion that this PART VI.] OF CRUSTACEA. S25 this sense resides in the Antennae. The Salivary Glands appear also to be wanting in the Animals of this class. Circulating System. The Heart, in some, as the Crab, is placed near the middle of the Thorax, and is of an oval form, but has no Auricle ; in others, as the Shrimp, it runs from one end of the Body to the other, like a Blood-vessel. The Heart here, as in the Mottus- ca Gasteropoda, receives the Blood from the Branchiae by one or more Veins, and sends out Arteries, which go to the different parts of the Body. From the extre- mities of the Arteries, Veins return by a Cava, which divides into Branchial Arteries upon approaching the Gills. Organs of Respiration. In the Crustacea, the Or- gans of Respiration consist of a set of Branchiae, or Gills, which are proportionally larger than in most of the Animals of the former class. In the Cancer tribe, they are placed at the sides of the Thorax, and near the origin of the Feet. In some, as the Shrimp, they lie under the Tail between the Fins, floating loose- ly in the water. The Gills vary in number and form in different Genera and Species ; but in all, they are near- ly of the same nature with the Gills of Fishes, and have the water constantly applied to them, so as to an- swer the different purposes of Respiration. Alimentary Canal. The Stomach is singular in this class, especially in the Crab, Lobster, &c. in being form- ed upon a kind of Osseous Skeleton. Near the Pylorus are five Teeth of unequal size, which, in some of these Animals, as the Lobster, are observed to be re-produced annually along with their external covering. The Teeth are 324* OF CRUSTACEA. [PART VI. are moved by particular Muscles, and possess a true power of mastication. The Stomach is situated in the Thorax above the Mouth, and, from its particular structure, is prevented from contracting and dilating like the Stomach of other Animals. The small Intestine is straight and cylindri- cal, but, towards its middle, it has a strong Valve and a long Caecum. Ltiver^ <$-c. The greater part of this class have no proper Liver. The Bile is derived from a collection of Intestinula Caeca, similar to those which supply the place of Pancreas in Osseous Fishes. They are of a yellow colour, and contain a bitter brown fluid, which they discharge into the beginning of the Intestine. These, together with the Stomach, fill almost the whole of the Thorax, the former composing the high-flavour- ed substance in the Crab and Lobster. Shrimps have a jLiver of a different nature from that of other Crustacea : being a solid Conglomerate Gland, arranged along the two sides of the Intestines, through their whole length. Organs of Generation. Here the Testes in the Male, and Ovaria in the Female, are in some united together, and their External Organs are double. In the Crdb> Lobster, &c. the Male has two Penes, and the Female two Vulvae. In the Male, the Testes are two Glandular-like Bo- dies, separate in the Crab, but united in the Lobster, and here placed under the Heart. From the Testes, two convoluted Vasa Deferentia pass out, which end in a corresponding Penis behind the Fifth Pair of Feet. Each PART VI.] OF CRUSTACEA. 325 Each of the Penes has a horny Sheath, which con- ducts it to the Vulva of the Female. Of the Females, the Lobster kind has the Ovaria united into one Body. Two short Oviducts go di- rectly to the Vulvae, which are simple Foramina in the substance of the Corslet or Thorax, at the base of the third pair of Feet. Crustaceous Females, after producing their Spawn or Ova, collect them at the Filaments of the Fins under the Tail, and carry them there till they open. PART PART VII. OF INSECTS. 1 NSECTS, like the other Genera of Invertebral Animals, want an Osseous Skeleton ; a horny substance, in the greater number of perfect Insects, serves them for Skin and Bone, inclosing the Muscles and Internal Organs, and giving attachment to the different Members. Some, as the Locust and Beetle, have Jaws large and distinct, placed in a lateral direction, and moving ho- rizontally ) others want them. Some have two Lips, the one above, the other below. They have articulated with the Head, Antennae, and with the Mouth or Jaws, Palpi or Feelers, for examining their nourishment. All the Insects with Jaws have the power of masticating hard Animal and Vegetable substances. All Insects, which possess Wings, metamorphose, or pass through certain changes before they arrive at their perfect form. In their first state, after leaving the Egg, they form Larva or Caterpillars. The Lar- va differ from complete Insects, chiefly in their Organs of motion. The Rings or Segments of which their Skin consists, are moved towards each other by Mus- cular FART VI.] OF INSECTS. 327 cular Bands situated within the Body. Sometimes they are covered by Bristles or Hooks, which enable them to lay hold more firmly of other substances. Many have Hairs or Spines upon the surface of their Body, which are cast off with the Skin at certain periods, and are afterwards re-produced. The Bodies of many Larva? have, at their under, and near their fore part, six Feet, each terminating in a hook, by which they can fix themselves, and draw the posterior to the anterior part of their Body. Some have, besides, a number of small Claws, to assist them in their motions. Others crawl by the assistance of hooked Mandibles, and by Tubercles on different parts of their Body. The Bodies of Insects are divided into Head, Cors- let, Pectus, Abdomen, and Members. The Head is joined to the Body, in some, by ball and socket ; in others, by plain surfaces \ in others, after the manner of a hinge. In some, the connection is entirely Liga- mentous, the different motions corresponding with the nature of the Joint. The Corslet or Thorax is situated between the Pectus and Head. The first pair of Feet are joined to this, and it contains the Muscles for mov- ing these and the Head. The Wings, when present, are fixed to the upper part of the Pectus, and the four posterior Feet to its under part. To the upper part a Horny Process is frequently fixed, termed Scutellum^ or Escucheon. The Pectus contains the Muscles which move the Wings and four pair of Feet. Abdomen. It commonly consists of different Rings. In 328 OF INSECTS. [PART VI. In some, it is directly continued from the Breast ; in others, there is an evident contraction between them, and a real Joint connected by Ligaments. Sometimes the Abdomen is terminated by a Sting, by Bristles, Plates, &c. Members or Feet, and Wings. In winged Insects, the number of the Feet is generally six, never less, but frequently more ; Scorpions, Spiders, &c. have eight ; Millipedes and Scolopendra, or Centipedes, have them attached to every ring of the Body. The Feet consist of the Coxa or Haunch, the Femur or Thigh, the Ti- bia or Leg, the Tarsus or Toe. Each of these is in- closed in a horny case, and moves as on a hinge. The Toe consists, in general, of several Joints, the last of which is terminated by one or two hooked Claws. The Articulations vary according to the mode of life. They are slender in many that burrow in the earth, as in the Scarabtzus. They are like Fans, and ciliated on the sides in those that swim, as in the Hydrophilus, or Diver. They have Viscous Balls, bristly Tufts, &c. in such as walk in smooth and slippery parts, as in the common Fly. In Insects that crawl upon Hairs, there are two moveable and opposite Claws, as in Lice, &c. Each of the Joints of the Feet is furnished with an Extensor and a Flexor Muscle, inclosed in the preced- ing Joint. The Wings are attached to the lateral parts of the Pectus. The greater number of Insects have four, some only two, some none. In some, they are purely Mem- branous j others have them covered with Farinaceous Scales PART VII.] OF INSECTS. 329 Scales of different colours. In the Coleoptera, &c. the Scales of the Wings, and in the Lepidoptera and some others, those of the Body, are small Horny Plates, laid over each other like the tiles on a house. The Muscles that move the Wings are not well as- certained. Some are small and short, and are supposed to extend or to fold them ; others are larger, for ele- vating or depressing them. Epidermis Insects in general, whether in the per- fect or imperfect state, possess an Epidermis. In the Larva, it is found to be several times shed before the Chrysalis state takes place. It varies in thickness in different Insects. In those living in water, it is com- monly of a Mucous nature. Perfect Insects have no Cutis, of course no Papillae Nervosoe. Their Palpi or Feelers are considered as proper Organs of Touch, by which the Animal examines surrounding objects. The Corpus Mucosum is placed between the Cuticle and Muscles in the Larvce, and is supposed to give ori- gin to the colour of Insects. In some, as the Fire- Flies in America, there is a Gelatinous shining colour, which gives light in the night. Brain and Nervous System The Brain, in Insects, may be considered as the anterior extremity of the Spi- nal Marrow, slightly enlarged. In the Larvae of large Insects, the Brain consists of one or more Lobes in a Horny Cavity in the Head. From these Lobes two Nerves commonly descend, and, embracing the Esophagus, unite into a Cord ana- logous to the Spinal Marrow. This extends through VOL. IV. X the $30 OF INSECTS. [FART V1L the Body, forming, in its course, ten or twelve Gan- glia, from which, and from the Brain, Nerves go off to the different parts of the Animal. In perfect Insects, the Brain has generally two Lobes, and is also situated above the Esophagus. The Nerves and Ganglia are sometimes similar ir> number, general appearance, and distribution, to those of Larvae ; at other times, they vary considerably in all these respects* Eye There are two kinds of Eyes in this tribe of Animals, some small and simple, and termed Stemmata, varying from two to eight in number ; others are large, appearing like a collection of smaller Eyes, but are only two in number. These are divided, in some Insects, into many hundred hexagonal convex surfaces, which appear like so many different Corneas or Lenses. The simple Eyes are found in most of the Aptera, and in the Larvae of many winged Insects, but are too small for examination. When the Larvae change into complete Insects, they change also their simple for compound Eyes. Several Genera of winged Insects and Aptera, are observed to have simple besides compound Eyes ; many Insects, on the other hand, have no Eyes. The Eyes of Insects have no Eye-lids, are commonly im- moveable, and, according to SWAMMERDAM, do not con- tain the same Humours which are found in the higher classes of Animals. The appearances of the Eyes of Insects are so diffe- rent from those in other classes, that experience alone shews them to be Eyes, When they are covered or cut out, the Animal can no longer find its way. The PART VII.] OF INSECTS. SSfl The Cornea of compound Eyes is lined with an opaque Mucus, varying in colour in different Insects. Behind this white spots appear, equal to the number of the Facets of the Cornea. On the back part of this a Choroides is found, which appears to receive a real Re- tina ; but further investigation is necessary to shew how the rays of light can reach the bottom of the Eye, so as to enable the Animal to form distinct vision. In the greater number of Insects, the Eyes appear to be des- titute of motion. Ear. The Organ of Hearing has hot been found in any of the individuals of this class, though it is not to be doubted that they enjoy the Sense of Hearing, since, in the Males, means are provided for calling the Females to them, which are heard by the latter, as is observed in the Crickets, Frog/toppers, Death-Watch, &c. Nei- ther is there any appearance of an Organ of Smell, though they give proofs of the existence of this Sense. They discover their Food seemingly by its smell, some- times even at a considerable distance ; and some, as the Flesh-JIy 9 frequently deposite their Ova on Plants, as the Arum Dracuntiitm and Stapelia Hirsuta, which have the smell of Carrion ; though, in such cases, the Mag- gots commonly perish through want. The part which has been considered, by some late Authors, as supply- ing the place of the Organ of Smell, is the Stigma, or entry into the Trachea; by others, the Antennae have been looked upon as answering this purpose. When Insects are deprived of their Antennae, it has been ob- served that they are incapable of recognizing their haunts, or their Food, though placed close by them. X 2 Organ, 332 OF INSECTS. [PART VII. Organ of Taste and Salivation. The seat of the Orjran of Taste in Insects is variable. The Under Lip by some, the posterior pair of Palpi by others, but commonly the long Tube in the Butterfly, has been con- sidered as the Tongue. Many of the Butterjlies, Bees, Ants, Common Flies, and Spiders, have a Spiral or Tu- bular Tongue, or a soft Proboscis, in a horny pointed Tube, by which they suck in their nourishment. No Salivary Glands are observed in the Mouths of Insects, though a fluid similar to Saliva, but varying in colour in different Insects, is observed to come from the Mouths of some of these Animals. Circulating System. No real Circulating System is found in proper Insects, yet many of these Animals, both in the Larvae and perfect state, have a Membra- nous Canal along the Back, in which alternate contrac- tions and dilatations are discerned. In the Caterpillar^ the pulsation begins at the posterior extremity of the Animal, and proceeds from one segment of the Body to another, till it arrives at the Head. This Vessel is therefore considered by some Authors as the Heart, but it is closed at the extremities. No Vessels, how- ever, are seen going from or to it. Nutrition and Secretion, therefore, are supposed to be effected in a different manner from what takes place in more perfect Animals. CUVIER considers the mode by which these are performed to be by Imbibition. Respiratory Organs. Respiration is performed by Tracheae ramified over most of the Body, but chiefly on the Intestines; there are, however, no Cellular r Lungs. The Tracheae are much larger and more nu- merous PART VII.] OF INSECTS. 333 merous in the Larvae of Insects, than in the perfect state. In Larvae, a Trachea runs on each side of the Body, under the Skin, and generally opens externally by nine or ten apertures, termed Stigmata. From these the same number of Air-vessels, or Branchiae, of a silver colour, pass off, to be dispersed through the Body by innumerable Branches, but particularly on the Alimen- tary Canal, and on the part .compared to the Omentum. The above is the most common distribution of the Tra- cheae ; but in several Aquatic Larvae, and even perfect Insects, the Air enters by two openings near 'the Anus, at the end of the Abdomen. Hymenoptera and Diptera have two principal Tracheae, with some small ones, at the base of the Abdomen. The Aranece have no Tra- cheae , their Organs of Respiration are confined to a few Vesicles, but which have an aperture at each side of the base of the Abdomen. The Tracheae of Insects are described by Authors as being composed of an outer, inner, and middle Mem- brane, the last of which is formed of Spiral Fibres. Insects are incapable of forming any Voice ; the noise many of them make is formed chiefly by their Wings. Alimentary Canal. The Esophagus is a straight short Tube, reaching from under the Brain to the first Gan- glion of the Nerves. The rest of the Canal differs or Polypus teith Arms, and also in Animals the productions of infusion, there is nothing like Nerves, yet they are sensible of heat. They prefer light to darkness, and have so far the sensation of Touch, as to feel the agitation of the water that sur- rounds themr Y2 The 348 OF ZOOPHYTES. [PART IX. The different Organs of the Senses are not demon- strable here, though, as in the Vermes, Zoophytes are to be considered as possessing Senses adapted to their manner of living. Vascular System. In the Echinus, two Vessels run along the Intestines, one considered as an Aorta, the other a Vena Cava, but without any visible Heart. From these a Plexus runs off, to be distributed upon the Intestines and Mesentery. Something of the same kind is to be observed in the Asterias. In the Echinus, there is a set of Tubes, considered by DR MONRO as Absorbents, which have a visibla Muscular structure, and without Valves. The outer end of each of the Tubes has a flat plate, by which the Ani~ mal adheres when it fixes upon, any object.. In the middle of the plate is an orifice, which imbibes the sea- water, that is conducted to Vessels in the inner part of the Shell. Each of the Ducts perforates the Shell by two Foramina ; and the different Foramina are pla- ced in five pairs of parallel lines, called by Naturalists Anibulacra y from their similarity to alleys in a garden. Upon the inner side of the Shell, they run to two ranges of Laminee, composed of Plexus of Vessels, from each of which a Duct runs to a large Tube, which receives all the Absorbents of one of the double ranges. The large Tube terminates in Reservoirs over the Sockets of the Teeth, through which it is supposed, that after a se- cretion has been made, the fluid absorbed is .returned to the sea. In the Medusa Ilhizostomes, and the Coriaceous Poly- FART IX.] OF ZOOPHYTES. pi, the Vessels which carry the nourishment come di- rectly or indirectly from the Stomach. In the Hydra, or Polypus with simple Arms, no Vessels are observed \ they imbibe their nourishment by means of the Pores of their Gelatinous covering ; and when their Body is even inverted, their external, now be- coming an internal surface, is found to digest their Food equally well with the other. The Monades, Protees, and other Microscopical A- nimals, are found to be the most simple of any, ap- pearing to be mere Gelatinous Masses, destitute of Mouth and Stomach, and receiving their nourishment through the surface of their Body. The Rotifera, Vorticella, and some other equally minute Animals, however, are observed to have a Stomach. Organs of' Respiration, The Vessels seen on the sur- face of the Animals of the order Echinodermata, as the Echinus, and the soft Gelatinous Zoophytes, as the Me- dusa, are supposed by some Authors to draw in nou- rishment from without, and to serve also as a sort of Respiratory Organs; but these are circumstances not, yet fully ascertained. The fresh-water Polypi, or Zoo- phytes strictly so called, imbibe nourishment through their whole surface. Of the order Infusoria, or Animalcula of Infusions, their diminutive size renders it impossible to ascertain any thing about their nature* Alimentary Canal and Cavity. In some of the indi- viduals of the class, there is an Alimentary Canal be- ginning by a Mouth, and terminating by an Anus. In others there is a Sac, simple or complex, In the first, the 550 OF ZOOPHYTES. [PUnx IX. the Canal is sustained by a Mesentery, which fixes it to the walls or covering of the Animal, as in the Echino- dermata, where, in some of these, as the Echinus and Holothuria, it makes turns within the Body, and ends in the Anus ; in others, as the Sipuncidus, it is a simple Canal ; and in the Asterias, a Sac in the centre of the Animal, from which two Canals extend into each of the Branches. In some of the others, as the Medusa, the Alimentary Canal is not suspended by the Mesentery, but is a com- mon Cavity in the general mass. The Stomach occupies the part termed Pedicle* From this Cavity Vessels arise, which convey the nou- rishment to the different parts of the Body. In some of the Medusae, there is a simple opening ; in others, there are Tentacula with open orifices, leading to Ca- nals, that, uniting together, form Trunks which con- vey the Food into the Stomach. This structure has been compared by CUVIER to the roots of trees, in con- sequence of which he forms a new Genus, termed Rhi- zostoma, or Mouth-root. The common Polypus has the most simple form of the Alimentary Canal, the whole Body being only a kind of Stomach, and having a single opening situated at the centre of the Tentacula, the Animal nourishing its spongy substance by imbibition. The Polypi, which, by their union, form the com- pound Animals that produce the different Lythophytes, are observed to have a nutritive system something simi- lar to the common Polypus and the Medusa. They combine the Stomachs of the former with the Vessels of IX.] OF ZOOPHYTES. 351 of the latter. Each Polypus has a Stomach, from which Tubes run into the Stalk which supports all the Polypi ; here they form a net-work, which occupies the whole of this substance. The Assistant Chylopoietic Viscera, viz. Liver, Spleen j and Pancreas, are entirely wanting in this class, Organs of Generation. All the Echinodermifa appear Jo be Hermaphrodite, and possess the power of fecun- dating themselves. Their Ovaria occupy a great part of their Body, especially when pregnant. Sometimes they are observed to be bathed in a milky liquor, which is supposed to be the Semen. The Echinus has five Lobes in the Ovarium or Roe. These open by several Ducts, which communicate, and pierce the Shell near the Anus. The Ovaria form the eatable part of this Animal. In the Asterias, the Ovaria form also five Lobes, one for each Branch of the Body, and these are composed of the Ova, which have a reddish colour. In the Hojothnria, there is a collection of slender Tubes, which greatly extend at particular seasons, and arc considered as the Ova ; but there is, besides, near the Anus, numerous white spiral Filaments, but whe- ther belonging to the Male Sex is uncertain. The Zoophytes properly so called, have no Genera- tive Organs ; they propagate by Buds and Slips, some- thing after the manner of the growth in Branches of Trees. In the Actinia and Polypi^ the young sprout out from any part of the external surface of the Parent. When they 352 OF ZOOPHYTES. [PART IX. they are divided, each of the portions forms a perfect Animal. Corals, Madripores, &c. are compound Polypi^ fixed upon a Calcareous Base, constructed by the Animals themselves. Sponges are also compound Animals, having a Vege- tating Root and Stem. In their recent state, they con- sist of an Animal Jelly. The only sign of life in them is a slight tremor and contraction on being touched. After death, the Jelly disappears, nothing but the base of the Animal remaining. /. Lilians & Sons, Printers, Edinburgh*