646 



MAMMALIA. 



Fig. 301. 



The skeleton of the Hippopotamus (Jig. 300) offers a good ex- 

 ample of the general disposition of the osseous system in the Pachy- 

 dermata. The spinous processes of the last cervical and anterior 

 dorsal vertebrae are necessarily of prodigious strength, giving origin 

 as they do to the muscles that support the weighty skull : the ribs 

 are numerous, broad, and flat ; they extend nearly along the entire 

 length of the trunk, and thus assist in sustaining the bulky viscera 

 of the abdomen. The pelvis is massive in proportion to the weight 

 of the body ; and both the thoracic and pelvic extremities short, 

 thick, and strong, forming, as it were, pillars upon which the trunk 

 is raised. 



The most important differences ob- 

 servable between the different genera of 

 Pachydermatous Mammalia are found in 

 the structure of their feet, and in the num- 

 ber and disposition of their toes. In 

 the Elephant there are five to each foot ; 

 but in the living state they are so encased 

 in the callous skin which forms a sort of 

 hoof to the foot of this monstrous animal, 

 that they are scarcely perceptible exter- 

 nally. In the Hippopotamus above de- 

 lineated there are four, and also in the 

 Hog tribes; but in the latter the two 

 middle toes are disproportionately large. 

 The Rhinoceros has only three toes to 

 each foot ; and other varieties in this 

 respect might easily be pointed out. 



(727.) In the SOLIDUNGULA, or So- 

 LIPEDS, regarded by Cuvier as a family 

 belonging to the order last mentioned, 

 we have a tribe of animals quite peculiar 

 as relates to the construction of their loco- 

 motive extremities. 



In the Horse, for example, a creature 

 obviously formed to be an assistant to 

 the human race, so completely has every 

 other consideration been sacrificed, in 

 order to ensure the utmost possible 

 strength and solidity in the structure of 

 the foot, that all the toes appear exter- 



