566 



Genus Hippopotamus. 



Dental formula :-i g, c j=}, p , in g=40. 



3404. The skeleton of a Hippopotamus (Hippopotamus amphibius). 



The vertebral formula is: 7 cervical, 15 dorsal, 4 lumbar, 6 sacral: 13 caudal vertebrae 

 are preserved, but a few terminal ones are wanting. The pleurapophysial parts of the trans- 

 verse processes of the third to the sixth cervical inclusive develope hatchet-shaped plates, pro- 

 gressively increasing in size, which overlap each other. The second and third cervicals have 

 bituberculate hypapophyses. The transverse processes of all the cervicals are perforated by 

 the vertebral arteries. Six pairs of ribs directly join the sternum, which consists of five bones 

 and a broad ensiform cartilage. A metapophysial ridge is developed above the diapophysis 

 of the eighth dorsal, changes its position and shape with increase of size in the two succeed- 

 ing vertebrae, in the eleventh projects forwards from above the prozygapophysis, and so con- 

 tinues throughout the rest of the dorsal and the lumbar series. There are no anapophyses, 

 but a broad plate is developed from the back part of each transverse process of the last lum- 

 bar, which presents an articular convexity for a corresponding concavity on the fore part of 

 the transverse process of the first sacral vertebra. The acromial angle of the scapula is 

 slightly produced : the coracoid is recurved. The greater tuberosity of the humerus is divided 

 into two subequal processes, the inner one separated by a deep and wide bicipital fossa from 

 the lower inner tuberosity. 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 

 foramina. The trapezium does not support any digit : of the other four, the two middle ones, 

 answering to the third and fourth, are most developed. The femur has no third trochanter. 

 The canal for the medullary artery commences at the upper and fore part of the shaft. The 

 fibula is distinct from the radius, and extends from its proximal end to the calcaneum. The 

 internal cuneiforme is present in the tarsus, but there is no rudiment of the innermost toe : 

 the proportions of the other four resemble those of the fore-foot. 



Mus. Brookes. 



3405. The skull of an old male Hippopotamus amphibius. 



The grinding teeth in the upper jaw have been reduced to the last two premolars and the 

 three molars, from the first and second of which the cusps have been worn down to the 

 common dentinal base. In the lower jaw the sockets of the last three premolara remain : the 

 molars are worn as in the upper jaw. 



Hunterian. 



3406. The skull of a less aged male Hippopotamus amphibius. 



The sockets of the four premolars remain on each side of the upper jaw, those of the first, 

 p 1, being unusually large : there is no trace of them in the lower jaw. The last molar, m 3, 

 is in place and has been slightly worn. The organs of hearing have been removed, and the 

 cranium is otherwise mutilated. 



Hunterian. 



