TRICHECHID A: 597 
Phocide ; but when on land the hind feet are turned forwards and 
used in progression, though less completely than in the Otartidd. 
The upper canines are developed into immense tusks, which descend 
wu long distance below the lower jaw. All the other teeth (Fig. 
273), including the lower canines, are much alike, small, simple, 
and one-rooted, the molars with flat crowns. The skull is without 
postorbital process, but has an alisphenoid canal. 
Trichechus.A—Dentition of young: i 3, ¢+, p andm 4. Many 
of these teeth are, however, lost early or remain through life in a 
rudimentary state concealed by the gums. The teeth which are 
usually developed functionally are i 3, ¢ 1, p 3, m %; total 18. 
Vertebrw: C7, D 14,L 6,8 4,0 12. Head round, Eyes rather 
small. Muzzle short and broad, with on each side a group of long, 
Via, 278,—Diagram of the dentition of the Walrus (Trickcehus rosmarus), The denticles 
placed apart from the others are milk-teeth, and disappear soon after birth. The small teeth 
in connection with the jaws frequently persist throughout life. 
very stiff, bristly whiskers. The remainder of the hair-covering 
very short and adpressed. Tail very rudimentary. Fore feet with 
subequal toes, carrying five minute flattened nails. Hind feet with 
subequal toes, the fifth slightly the largest, having cutaneous lobes 
projecting beyond the ends as in Oturiv , first and fifth with minute 
flattened nails; second, third, and fourth with large, elongated, 
subcompressed pointed nails. 
Trichechus is the almost universally accepted generic name by 
which the Walrus or Morse? is known to zoologists, but some con- 
fusion has been introduced into literature by the revival of the 
nearly obsolete terms /tosmarns by some authors and Odelenus ly 
others. 7. rosmearus is the name of the species met with in the 
Arctic seas ; that of the North Pacific, if distinct, is 7. obesus. The 
preceding and following descriptions will apply equally to both. 
1 Linn, Sys, Nat, 12th ed, vol. i. p. 49 (1766). 
* The former word is a modification of the Scandinavian vallross or hvalros 
(‘whale-horse’’), the latter an adaptation of the Russian name for the animal. 
