FOSSIL EEMAINS. 57 



jaw, (2) the enormous development of the ni>per canines, (3) the 

 slight specialization of the lower canines, and (4) the caducous 

 character of the two posterior pairs of molars of the upper jaw 

 and the posterior pair in tlie lower jaw. The early dentition of 

 the Walrus differs mainly from that of most other Pinnipeds in 

 having six lower incisors instead of four, the incisive formula of 

 other Pinnipeds, as generally recognized, being usually |^, fre- 

 quently 1^, and sometimes (as in Macrorhinus and Cystophora) 

 1^, never, at least in the permanent dentition, |^, but I am 



far from siu^e this number may not sometimes appear in the 

 deciduous dentition. In the Sea Otter [Enliydris), there are 

 said to be six lower incisors in the yoiuig, while only four are 

 present in adult life. The middle pair of lower incisors so early 

 disappear that even in very young specimens they are some- 

 times wanting. Eapp found in a foetal specimen three on one 

 side and only two on the other, and quite a number of promi- 

 nent writers on the subject have recognized two pairs of lower 

 incisors as the normal number. In many specimens, the alveoli 

 of three pairs have been found, and, in addition to the instances 

 akeady given, I may add that there is a young skull in the 

 Museum of Comparative Zoology that shows decided traces of 

 three i)airs, the outer incisor on one side being still in place. 



In view of all that is at jiresent known respecting the sub- 

 ject, I adopt the following formulai as being well-estabhshed, 

 premising, however, that they are substantially in accord with 

 the view of the case presented by Professor Flower in 1869 : 



Temporary dentition: I. |^; ^-i^; ^I- j5l = il = 32. 



Permanent dentition : I. ^J; 0. J-^^j M. ie| = j| = 26; the 

 last two upper molars and the last lower one on each side 

 being rudimentary and often absent, 



Fossil Eematns. Eemains of the Atlantic Walrus, in a fossil 

 state, have been found at various i)Ouits along the Atlantic 

 coast from Maine to South Carolina, and in Europe as far south 

 as England and France. The first noticed Irom American locali- 

 ties was thus mentioned by Barton in 1805, but the locality 

 is not given. He says: "The bones of one of these large 

 animals have been found. These appear to have belonged to 

 a species of fricJieclms; perhajis to the tricJicchus rosmarvs or 

 morsc.''^* Messrs. Mitchill, Smith, and Cooper described, in 



* London Pliil. Mag., vol. xxxii, 1805, p. 98. 



