FAMILY ODOB^NIDJl. 



Walruses. 



" lYichecidce, GRAY, London Med. Kepos., 1821, 303" (family). Apud Gray. 

 Trichechidce, GRAY, Ann. of Philos., 1825, 340; Ann. and Mag. Nat. Hist., 3d 



ser., xviii, 1866, 229; ibid., 4th ser., iv, 1869, 268; Suppl. Cat. Seals 



and Whales, 1871, 5 (family). 

 Trichecina, GRAY, London's Mag. Nat. Hist., i, 1837, 538; "Zool. Erebus and 



Terror, 3 " (subfamily). In part only, or exclusive of Halichcerus. 

 TricJiecUna, GRAY, Cat. Mam. Brit. Mus., pt. ii, 1850, 29; Cat. Seals and 



Whales, 1866, 33 (subfamily). In part only = Trichedna Gray, 1837. 

 " Trichechidce seu Campodontia, BROOKES, Cat. Anat. and Zool. Mus. 1828, 37." 

 Trichechoidea, GIEBEL, Fauna der Vorwelt, i, 1847, 221: Saugeth., 1855, 127 



(family). 



Trichedna, TURNER, Proc. Zool. Soc. Lond., 1848, 85, 88 (subfamily). 

 Kosmaridce, GILL, Proc. Essex Institute, Y, 1866, 7, 11 ; Families of Mam., 



1872, 27, 69, 70 ( = " TrichecMdw Brookes, Gervais"). ALLEN, Bull. 



Mus. Comp. Zool., ii, 1870, 21. 



Rosniaroidea, GILL, Fam. Mam., 1872,70 ("superfamily" = Rosmaridce Gill). 

 Broca, LATREILLE, Fam. Reg. Anim., 1825, 51 (family). 

 Les Morses, F. CUVIER, Dents des Mam., 1825, 233 ; Diet. Sci. Nat., lix, 1829, 



465 (family). 



GENERAL OBSERVATIONS. 



Among the distinctive features of the Odobcenidce are the 

 enormous development of the upper canines, and the consequent 

 great enlargement of the anterior portion of the skull for their 

 reception and support, the early loss of all the incisors except 

 the outer pair of the upper jaw, the caducous character of the 

 posterior molars, and the molariform lower canines. The Wal- 

 ruses share with the Eared Seals the ability to turn the hind 

 feet forward, and consequently have considerable power of loco- 

 motion on land. This is further aided by a greater freedom of 

 movement of the fore feet than is possessed by the Earless 

 Seals. The Walruses differ from the Eared Seals by their 

 much thicker bodies, shorter necks, and longer caudal vertebra}, 

 the dorsal and lumbar vertebrae remaining of proportionately 

 the same length. In consequence of their obesity, the ribs and 

 the proximal segments of the limbs are longer in the Walruses 

 than in the Eared Seals, while the distal segments of the limbs 

 are relatively shorter. The scapula is long and narrow, instead 

 of short and broad, as in the Otariidce, and its crest is placed 



5 



