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University of California Publications in Geology [Vol. 13 



As remarked before, all the phocids now existing in the Antarctic 

 regions are of large size. Under the prevailing conditions of life, 

 competition is most severe between those forms which are dependent, 

 in the main, on the same tj r pes of food. The present occurrence of 

 the Lobodoninae in the Antarctics strikingly confirms this. Both 

 Leptonychotes weddelli and Lobodon carcinophaga occur in relatively 

 large numbers, though neither encroaches on the other to any marked 

 extent, either in the types of food or in the feeding grounds. The 

 former is a fish eater, and Lobodon has acquired the name of crab 

 eater because its food is composed to a large extent of crustaceans. 

 The other two genera of this subfamily, Hydrurga and Ommatophoca, 

 are not so plentiful, the latter in fact is quite a rarity, but their food 

 is more varied. 



In the Lobodoninae are to be found the most conspicuous examples 

 of secondary modification of tooth pattern in the pinnipeds. They 

 can hardly be called the less progressive types of the Phocidae. The 

 dubious lobodonid tooth from the Upper Cretaceous of New Jersey, 

 if valid, would necessarily upset many of our present concepts on the 

 history or derivation of the present type of dentition in the Phocidae. 

 In this tooth there are present the same cusps as are possessed by the 

 living genus, Lobodon. 



The present distribution of this subfamily indicates that its mem- 

 bers for some reason or other left the Phocinae in possession of the 

 Holarctic region while they in turn took possession of the Antarctics. 

 Whether or not they were forced out or crowded into new feeding 

 grounds is a matter of conjecture in the light of our present evidence. 

 The fact is that they have maintained themselves and now exist there 

 to the exclusion of the Phocinae. 



CYSTOPHORINAE 

 During the Middle Pliocene, the form Mesotaria ambigua, allied to 

 Cystophora, is known from the deposits of the Antwerp basin, and 

 in the uppermost Miocene another form, closely allied to Mirounga, 

 ranged along the eastern coast of North America at least as far north 

 as Massachusetts. Today the genus Mirounga is limited for the most 

 part to southern oceans, though until very recently Mirounga, angusti- 

 rostris was fairly common on the coast of Lower California. The 

 other form, Mirounga leonina, is only an occasional visitor to the 

 Antarctic shores, though its range extends from the Heard and Ker- 

 guelen Islands, in the Indian Ocean southeast of Madagascar, to South 



