VERTEBRATA. 31 



chest. In ungulated animals, where there are no clavicles, the 

 sternum- is compressed laterally, and projects in the centre like a 

 ship's keel. The superior piece of the sternum is very considera- 

 ble in the mole, where it forms a distinct bone. It is proportionably 

 small in the bat, seal, horse, rhinoceros. In the cetacea it is 

 short and large, being composed of five pieces in the dugong, and 

 three in the dolphin, the porposse, and the platanist. In the bat 

 and ornithorhynchns, the upper part of the sternum is T-shaped, 

 the transverse process being for the articulation of the clavicle. 



The figure of the thorax in most apes, bats, and the greater 

 number of the rodentia, and, in fact, of the class mammalia, having 

 clavicles, agrees with that of the human subject. In ungulated 

 animals, on the contrary, where there are no clavicles, the thorax 

 is laterally compressed and elongated. 



The whole arrangement of the thorax proclaims man to be 

 destined to move in the erect attitude: he is the only animal in 

 which its transverse exceeds the antero-posterior diameter; even in 

 the chimpanse, which approaches nearest to him, the latter exceeds 

 the former measurement, reminding us of the form of this cavity 

 in the very young subject. Its great lateral width and inconsider- 

 able depth from sternum to spine, throw the arms apart, and in- 

 crease their sphere of motion. The reverse characters, together 

 with the absence of clavicles in quadrupeds, allow the fore legs to 

 approximate, to fall perpendicularly under the front of the body, 

 and support it with ease and security. 



Head. — We shall cease to wonder at the striking" differences 

 observed in the construction of this part of the skeleton, when we 

 consider that it forms the receptacle for the brain, most of the ex- 

 ternal senses, the masticatory apparatus, &c. Man combines by 

 far the largest cranium with the smallest face; and animals deviate 

 from these relations in proportion as they increase in stupidity and 

 ferocity. In man, the area of the section of the cranium is nearly 

 four times as large as that of the face; three times as large 

 in the ourang-outang; twice as large in the sapajous; and they 

 are nearly equal in the baboons and carnivora. In the hare 

 and marmot, the face exceeds the cranium by one third; in the 

 porcupine and ruminants, by one half. The face is three times 

 as large as the cranium in the hippopotamus, and four times 

 as large in the horse. 



The superior maxillary bones of the human subject are united 

 to each other, and contain all the upper teeth ; in some other 

 mammalia, however, they are separated by a coniform bone, which 

 contains the incisor teeth, and hence named os insicivum; but it 

 exists where there are no incisor teeth, as in the kerotophara, the 

 elephant, and the two-toed rhinoceros of Africa, and even where 

 there are no teeth at all, as in the ant-eater and some of the ceta- 

 ceans, for which reason Blumenbach calls it os intermaxillare. In 

 some it is a single bone, in others double; it is absent from the 

 chimpanse, though present in the ourang-outang. The former of 



