66 University of California Publications in Geology [Vol. 13 



crown on the molariform series, some of which occasionally had small 

 secondary cusps. 



If future exploration should result in the discovery of true otarids 

 in Europe during the Oligocene, then Matthew's 80 theory that the 

 arctic North Atlantic basin afforded the most favorable region for the 

 origin of the pinnipeds would have additional support. Most writers 

 have assumed that the distribution of the Otariidae in the past was 

 much the same as it is today. Since three distinct forms with otarid 

 relationships are known from the Pacific coast during the Miocene, one 

 is led to believe that they must have had their origin somewhere in 

 the North Pacific Ocean. 



ANCESTRAL PHOCIDAE 



More difficult problems present themselves in an attempt to settle 

 the relationships of the various members of the Phocidae than confront 

 us in either the Otariidae or the Odobenidae. Not only, from all 

 appearances, have they been the longest adapted to life in the water 

 and are consequently highly specialized, but also all the known 

 Phocidae from the Miocene appear to be almost on a par in special- 

 ization with the existing species. This is especially true of the genus 

 Phoca. Indeed, some of the known fossils are with difficulty distin- 

 guished from Phoca vitulina. In other words, in some genera there 

 has been little if any progress since the Miocene so far as skeletal 

 characters are concerned. One might be led to a belief in the multiple 

 origin of the Pinnipedia were it not for the marked uniformity in the 

 vertebral formula and other skeletal features of the three families. 



Our knowledge of the geographical distribution of the Phocidae 

 will rapidly widen when the marine beds are more thoroughly 

 explored. Our present knowledge is more or less the result of acci- 

 dental discovery of isolated bones and not because of any systematic 

 search for pinniped material. The famous deposits of the Antwerp 

 Basin owe much of their importance to a government project for 

 building a set of canals in the neighborhood of Antwerp. We first 

 note the questionable absence of otarids in the deposits of Europe, and 

 their occurrence in four widely separated deposits, viz. : the Argentine 

 Republic, Australia, California, and Oregon. At the same time we 

 note that some of the earliest known phocids resemble or appear to 



g 6 Matthew, W. D., Climate and evolution. Ann. New York Aead. Sci., vol. 24, 

 pp. 223-224. 1915. 



