MAMMALIA. 433 



In removing the walruses from tlie seals, to bring tliem near the pachy- 

 derms, we agree with the views brought forth a year ago by a most skilful 

 American anatomist (Proceedings of the Boston Society of Natural History, 

 III. 1850, p. 242). 



Sirenidia and Walrus together undoubtedly belong to that great group 

 called Pachydermata, but do not constitute a single series. The pachy- 

 derms need to be revised carefully, and the numerous extinct genera once 

 more compared with both the aquatic and terrestrial living types. 



Fam. Trichechid^e is the only one of the group, and contains but one 

 single genus, the genus Trichechus^ composed only of one well ascertained 

 species, T. rosmarus {pi 114, Jig. 3), of the history of which the following 

 is an exti'act from Bell's History of the British Quadrupeds : — 



" The form of this animal is extremely unwieldy ; its bulk, in comparison 

 with its length, being greater than in any other form of Phocidce. This, 

 with the relative small size of the head, the full, thick muzzle, and the long 

 tusks, directed downwards, gives it a most strange appearance. Like the 

 seals, it frequents principally the northern regions, where multitudes of 

 them associate in herds on the rocks or ice fields, throwing themselves off 

 on the first approach of danger into the sea, where they are as active and 

 as much at home as the seals* themselves. The walrus, however,, from the 

 form and structure of its teeth, cannot live upon fish to the exclusion of 

 vegetable food. The small number of grinding teeth, and more especially 

 their extreme shortness and rounded form, are calculated rather to bruise 

 the half pulpy mass of marine vegetables, than tO' hold and pferce the 

 slippery hardness of the fish's scaly cuirass. One of the most remarkable 

 peculiarities is the form and size of the superior canine teeth, which are 

 directed downwards, and are extremely long and powerful, constituting a 

 pair of defences of immense strength. 



" The walrus is found only in the colder regions ; it comes often on 

 shores or on the ice, and remains there sometimes in herds of forty, eighty, 

 a hundred or more, for days together, until they are driven to the sea either 

 by alarm or hunger. They are often killed on land at Spitzbergen and 

 other northern coasts, by means of a lance or spear, for the sake of their 

 oil, and the ivory of their tusks, which is much more valuable than that of 

 the elephant, on account of its superior whiteness and density. Of late 

 years, the pursuit of these animals has greatly diminished their numbers, or 

 at least taught them more caution, and rendered them extremely fearful of 

 their arch-enemy. In the water, the chase of the walrus is exceedingly 

 difficult. The extreme thickness and hardness of their skin render it 

 impervious even to the stroke of the harpoon, unless well directed and sent 

 with great force. 



" Before the persecution above alluded to had taught them to be- appre- 

 hensive of the approach of mankind, they were often found at a considerable- 

 distance from the sea \ and as the hunters placed themselves between them 

 and the water, numbers were intercepted in their retreat, and readily 

 destroyed. Of the carcases of the first that fell the hunters made a^ sort of 

 barrier to oppose the remainder ; and in this way, on some occasions, three 



637 



