1922] Kellogg: Pinnipeds from Miocene and Pleistocene Deposits 67 



belong to the same subfamilies as are currently in use for existing 

 forms. From the evidence afforded by fossil remains, it seems that 

 the ancestry of the Lobodoninae is a mystery, though they may pos- 

 sibly be explained as an offshoot of the Monachinae. 



On the other hand, the questioned presence of a presumed lobo- 

 donid type, Lobodon veins, in the Upper Cretaceous green sands of 

 New Jersey further complicates the matter. If additional fossils are 

 ever found in the same beds or in other beds of similar age, it will 

 place the ancestry of the phocids as far back at least as the Lower 

 Cretaceous. On such a supposition only, could one explain the per- 

 fection of such a highly specialized tooth as is exhibited by Lobodon 

 vetus. The origin of the otarids was probably not later than the 

 Eocene and certainly not later than the Oligocene. One hesitates to 

 assume a separate ancestry for the phocids, but that conclusion would 

 be confirmed by the presence of phocids in the Upper Cretaceous. 



As to life in the littoral areas of oceans, attention may be especially 

 directed toward the favorable environmental conditions prevailing 

 throughout the Miocene and the Pliocene. The changes appear to be 

 those of progressive modification and reduction of size rather than 

 the splitting off into new types. The early forms, so far as known, 

 were all rather large, though for the most part somewhat specialized 

 for pelagic life. The present forms living in the Holarctic region 

 are relatively small compared to these types. On the other hand, 

 almost all the forms, without exception, now existing in the Antarctic 

 region are of large size. One form in fact, the sea elephant, Mirounga, 

 occasionally reaches a length of thirty feet and attains a weight of a 

 ton or more. 



Scattered and intermingled often with these pinniped remains, 

 are numerous teeth and other skeletal elements of squalodonts and 

 other cetaceans, which often proved puzzling and confusing to the 

 describer and resulted in considerable confusion in the literature on 

 this group. It will be observed that some of the teeth figured as 

 belonging to squalodonts, resemble in some respects the Lower Miocene 

 Allodesmus. Remains of pinnipeds are far more scarce in North 

 America than in Europe. The fact that pinnipeds are more or less 

 gregarious and that they are restricted to certain rookeries because 

 of littoral conditions may explain their absence from many marine 

 formations. 



The origin of the dentition of this group remains a highly debatable 

 question. In order to make any attempt at a solution, it would be 



