WALRUS. 161 



dentition, on the other hand, is quite unlike that of either of 

 the other two Famihes of the sub-order, the upper canines 

 forming enormous downwardly directed tusks, while all the 

 other teeth are inserted by single roots, and have very simple 

 crowns, which in those of the cheek-series are flattened. 



THE WALRUSES. GENUS TRICHECHUS. 

 Trichechus, Linn., Syst. Nat. ed. 12, vol. i. p. 49 (1766). 



Size very large ; head rounded, with relatively small eyes, 

 and the muzzle short and wide ; tail rudimental ; the five toes 

 of the fore-feet of nearly equal length, and furnished with 

 minute flattened nails ; in the hind-feet, the fifth toe slightly 

 the largest, and, like the first, with a nail like those of the fore- 

 feet, the nails of the three middle toes being long, narrow, and 

 pointed ; the webs of the hind-feet projecting in advance of the 

 toes in the form of lobes. In the adult only eighteen teeth, 

 forming a pair of small incisors in the upper jaw, and another 

 of enormous canines ; the lower canines being small, and very 

 similar to the pre-molars, of which there are three pairs in each 

 jaw. 



THE WALRUS. TRICHECHUS ROSMARUS. 



Trichechus rosmarus, Linn., Syst. Nat. ed. 12, vol. i. p. 49 

 (1766); Gray, Cat. Seals and Whales Brit. Mus. p. 36 

 (1866); Bell, British Quadrupeds, 2nd ed. vol. i. p. 269 

 (1874). 



Rosmarus arcticus, Pallas, Zoogr. Rosso.- Asiat. vol. i. p. 269 

 (1811). 



Odobanus rosmarus, Allen {ex Malmgren), North American 

 Pinnipeds, p. 23 (1880). 



Characters. — Muzzle furnished on each side with a bunch of 

 quill-like bristles ; hair short and closely pressed to the skin, of 

 5 M 



