I.-THE PRIBILOF FUR SEAL. 



THE MAIN DIVISIONS OF THE PINNIPEDIA. 

 By Frederic A. Lucas. 



The lines of descent of the Pinnipedia are very imperfectly known, and little can 

 be said save that both eared and earless seals have descended from the Oreodonta, the 

 earless seals having become most highly specialized, while the eared seals are more 

 generalized and are structurally nearer the bears. From their distribution it would 

 seem that the eared seals, and especially the fur seals, originated in the southern 

 hemisphere and differentiated as they worked north. Furthermore, that this 

 northward movement was along the west coast of America, being favored by the cold 

 current setting northward along the coast of South America. 



The northern seals have become generically distinct from their southern relatives, 

 while the Asiatic and North American animals are more or less differentiated from one 

 another, their differences being accorded specific value by Dr. Jordan. 



In his Families of Mammals, Dr. Gill, although strongly tempted to do otherwise, 

 grouped the eared and earless seals together in the superfamily Phocoidea, the 

 walruses being set apart as a second superfamily Rosmaroidea. 



Dr. Allen' made a different disposition of the pinnipeds, making the groups 

 Gressigrada and Keptigrada, the former containing the Odobaenidw and Otariidce, the 

 latter comprising the Phocidm. 



It has seemed to us better to follow Dr. Gill's unpublished ideas and to combine 

 the eared seals and walruses in the superfamily Otarioidea, the earless seals forming 

 a second superfamily Phocoidea. 



With better material at hand than was in Dr. Allen's possession, it is possible to 

 extend his diagnosis somewhat, and the foUowing characteristics of the two super- 

 families are herewith submitted. 



OTARIOIDEA. 



Neck long, hind feet capable of being turned forward and used in terrestrial 

 locomotion. Grinders with single roots and simple, flattened or pointed crowns. 

 Skull with mastoid large and salient, and large tentorium ; an alisphenoid canal. 

 Posterior ends of nasals abutting upon ( OdoibcenidcB) or separated by frontals ( Otariidce). 

 Anterior feet without claws, and with a broad cartilaginous border extending beyond 

 the digits. Hind feet with phalanges terminating in long cartilaginous flaps, and 

 with-claws on three innermost digits only. Astragalus much shorter than calcaneum. 



' History of North American Pinnipeds, pp. 3, 4. 



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 5974— PT 3 1 



