FOSSIL EEMAINS. 57 



jaw, (2) the enormous development of the upper 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 the lower jaw. The early dentition of 

 the AValrus 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 f^J, and sometimes (as in MacrorMnus and Cystophora) 

 |=| ? never, at least in the permanent dentition, |=|, but I am 

 far from sure 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 young, 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- 

 tunes 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 

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

 Museum of Comparative Zoology that shows decided traces of 

 three pairs, the outer incisor on one side being still in place. 



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

 ject, I adopt the following formula} as being well-established, 

 premising, however, that they are substantially in accord with 

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



Temporary dentition: I. |=|; C.^; M. ^ = g = 32. 



Permanent dentition : I. ^ ; 0. }={ j M. f^f = g = 26 ; the 

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

 being rudimentary and often absent. 



FOSSIL EEMAINS. Remains of the Atlantic Wajrus, in a fossil 

 state, have been found at various points along the Atlantic 

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

 as England and France. The first noticed from 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 trichechus; perhaps to the triclicclms rosmariis or 

 morse."* Messrs. Mitchill, Smith, and Cooper described, in 



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



