SKELETON OF HIPPOPOTAMUS. 



765 



bones, the bulky head, and even the variable and irregular teeth that 

 arm the ponderous jaws are all again conspicuous in the PACHYDERM ATA ; 

 and the river and the marsh, the localities frequented by the latter, as 

 obviously indicate the intermediate position which these animals occupy 

 between the aquatic and the terrestrial Mammalia. 



(2199.) The skeleton of the Hippopotamus (fig. 386) offers a good 

 example 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, form, as it 

 were, pillars upon which the trunk is raised. 



Fig. 386. 



Skeleton of Hippopotamus. 



(2200.) The most important differences observable between the 

 various genera of Pachydermatous Mammalia are found in the structure 

 of their feet, and in the number 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 externally. In 

 the Hippopotamus, above delineated, 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. 



(2201.) In the SOLIDUNGTJLA, or SOLIPEDS, regarded by Cuvier as a 

 family belonging to the order last mentioned, we have a tribe of ani- 



