WALRUS. 221 



quently single roots ; the first smaller than the last 

 incisor, the second and third largest, the fourth 

 much smaller, the fifth very small, all shortly coni- 

 cal, and blunt, with enamel on the tip only. The 

 canine tooth is also at first enamelled at its extre- 

 mity. In the lower jaw are two very small conical 

 incisors on each side ; the canine tooth is wanting ; 

 five grinders, with single conical compressed roots, 

 and short compressed conical crowns, enamelled at 

 the point ; the first, second, and third nearly equal, 

 the latter being a little larger, the fourth much 

 smaller, and the fifth very small. The tusks, or 

 enormously developed canine teeth of the upper 

 jaw, are compressed, conical, a little curved back- 

 ward, directed downwards and a little forwards, and 

 somewhat diverging, but in some individuals, when 

 very long, they again converge toward the points. 

 In adults, the incisors are obliterated, excepting the 

 lateral pair of the upper jaw ; the fifth grinder in 

 both jaws has also disappeared, and sometimes the 

 fourth in one or both jaws. A circumstance that 

 seems to me very singular, and for which I cannot 

 account, is, that although the grinders are so placed 

 as to meet at the points only, the outer surface oi 

 the lower not falling within the line of the upper so 

 as to meet their inner surface, nor the reverse, in 

 any possible case, the jaw having no lateral motion, 

 which is rendered impossible both by its articulation 

 and by the barriers formed by the tusks, yet the in- 

 ner surface of both upper and lower grinders is 

 obliquely worn, in old individuals in a very remark- 



