30 EVERS'S COMPARATIVE ANATOMY. 



In most animals, it has been said, that the head and neck together 

 equal in length the fore-feet, except where the latter are used as 

 hands, as in the apes and rodentia. The neck attains its greatest 

 length in the genus cameius, and is shortest in the order cetacea, 

 owing to the consolidation of the vertebrae. According to the 

 statement of Gore, the number of cervical vertebras in certain of 

 the cetacea, as the balaena, manatee, and dugong, amounts only to 

 six. In the rodentia, and most long necked animals, the spinous 

 processes are almost wanting. The atlas, in the carnivora, rumi- 

 nantia, solipida, pachydermata, <fec, is distinguished by its length, 

 and by its large aliform transverse processes. The free motion and 

 beautiful arch observed in the necks of some horses, camels, &c, is 

 explained by the bodies of the cervical vertebras having a perfect 

 articular head on their upper surface, and a corresponding depres- 

 sion on their lower, similar to what we observe in the necks of 

 serpents, with this difference, that the surfaces are reversed. The 

 ruminantia, rhinoceros, elephant, &c, are remarkable for the great 

 length of the spinous processes of the dorsal vertebrae. Bats have 

 scarcely any spinous processes; and, with the exception of the 

 second dorsal, they are short in the rodentia. In the lumbar ver- 

 tebrae, the form of the transverse processes is very variable — almost 

 absent in bats, very strong in the ruminantia, rodentia, and carni- 

 vora. The megatherium possesses long spinous processes. In the 

 sloth, the length, breadth, and consolidation of the sacral vertebrae 

 remind us of the sacrum of birds. The few first only of the caudal 

 vertebrae in mammalia contain a prolongation of the vertebral canal. 

 Animals with long movable tails, as the two-toed ant-eater, have 

 oblong triangular processes on the under surface of the caudal 

 vertebrae, as in the crocodile. The connection of the vertebrae is 

 almost always by means of interarticular cartilage, as in man, and 

 consists of concentric rings, most evident in the whale. In the 

 pig and rabbit the interarticular cavities are filled with an albu- 

 minous fluid, as in fishes. 



Ribs. — Man has seven true and five false ribs ; the balaena 

 whale, one true and eleven false ; in the unau, or two-toed 

 sloth, there are twenty-three pairs, of which eleven are false ; in 

 the horse eighteen, and eight of them false; in wolves, cats, and 

 some apes, there are thirteen pairs, four of which are false; in the 

 guinea pig, armadillo, and porpoise, there are thirteen, of which 

 seven are false ; in the manatee, of sixteen pairs, but two are true; 

 in the dugong but three out of eighteen ; and in the ornithorhynchus 

 but six out of seventeen. The breadth of the ribs is greater in the 

 ruminantia, pachydemata, in the manatee, and especially in the 

 two-toed ant-eater, than in other mammalia. The connection of 

 the ribs with the sternum is in general effected by cartilage; but in 

 the cetacea, ant-eaters, dasypus, bradypus man is, ornithorhynchus, 

 echidna, and frequently in bats, the union is completely bony. 



Sternum. — This bone, though essentially the same as in the 

 human subject, is somewhat modified in form by the shape of the 



