SKULL OF THE HIPPOPOTAMUS. 179 



that of the rhinoceros. In points of minor importance, 

 we find the hippopotamus resembling the rhinoceros ; as 

 €. g. in the shortness and strength of its neck ; but it has 

 only fifteen dorsal, d^ and four lumbar, ?, vertebrae. The 

 spines of these vertebras are shorter and less unequal 

 than in the ruminants; and they have an almost uniform 

 direction, as in all quadrupeds that do not move by leaps 

 or bounds. The tail is short, and, in the living animal, 

 compressed, acting like a rudder. The bones of the 

 limbs are short and thick. In the scapula, 51, the acro- 

 mion is slightly produced, and the coracoid recurved. 

 The great tuberosity of the humerus, 53, is divided into 

 two subequal processes. The ulna and radius have 

 coalesced at their extremities, and at the middle of their 

 shaft, the interosseous space being indicated by a deep 

 groove and two holes. In the carpal series of bones, the 

 trapezium is present, but does not support any digit; the 

 innermost, answering to the thumb or pollex, therefore, 

 is the one which is absent; of the remaining four digits, 

 the two middle ones, answering to the third and fourth, 

 are most developed. The femur has no third trochanter. 

 The fibula is distinct from the radius, and extends from 

 its proximal end to the calcaneum. The entocuneiform 

 bone is present in the tarsus, but there is no rudiment of 

 the innermost toe or hallux ; the proportions of the other 

 four toes resemble those on the fore-foot. 



The skull is remarkable for the prominence and high 

 position of the orbits, which allow the eye to be projected 

 above the surface of the water, and a survey to be made 

 by the suspicious animal without the exposure of any 

 other part of the head. The upper jaw is peculiar for 

 the development of the sockets of the great canine teeth, 



