90 



SCIENCE. 



[N. S. Vol. XXIV. No. 603. 



ing a number of primitive or ancestral char- 

 acters not found in the skeleton of any- 

 modern pinniped. He has appropriately 

 named the new genus Desmatophoca oregon- 

 ensis. 



The age of the horizon in which this fossil 

 was found is determined by Professor Condon 

 to be Miocene from the association of a large 

 number of characteristic genera of marine 

 shells. Whether it represents the entire series 

 of fresh-water deposits included in the Oligo- 

 cene and Miocene of the interior continental 

 region or whether it is equivalent to only a 

 part of them can not now be determined. I 

 think it may be safely assumed, however, to be 

 the equivalent of the entire series, although 

 its vertical thickness is considerably less than 

 the contemporary fresh-water beds. The 

 position of the fossil within the deposit was 

 not accurately recorded but there is reason to 

 believe that it comes from a layer which would 

 suggest a Middle Oligocene age if referred to 

 the interior series. 



The point of greatest interest and impor- 

 tance in connection with the fossil under con- 

 sideration is to be found in the light which 

 it throws upon the broader question of the 

 origin of this highly modified and almost ex- 

 clusively aquatic branch of the carnivorous 

 mammals. Hitherto an understanding of the 

 more exact genetic connections between the 

 Pinnipedia and the land Carnivora has proven 

 a very obscure and perplexing problem to the 

 morphologist, and as a result various opinions 

 have been expressed concerning its solution. 

 There seems, however, to have been entire 

 unanimity of opinion in the hypothesis that 

 the pinnipeds are descendants of some mem- 

 ber of the land Carnivora and that their ex- 

 treme modification has been due to the assump- 

 tion of an aquatic habit with the attendant 

 changes in structure necessitated by this en- 

 vironment. 



Huxley held that the seals (using this term 

 in its broader sense) have been derived from 

 the bears and he attempted to point out 

 similarities of structure between the two 

 groups. In this view Mivart entirely con- 

 curred. The chief objections to this hypoth- 



esis are the following: The bears have now 

 been pretty thoroughly proven by Sehlosser to 

 be descendants of the canoid or dog phylum, 

 through AmpMcyon, dating no further back 

 than the later Oligocene or earlier Miocene. 

 In the fossil seal before us we have a very 

 distinct pinniped, at least equivalent in age 

 to Amphicyon exhibiting no approach what- 

 ever to the dog or bear groups. This hy- 

 pothesis may, therefore, be dismissed as wholly 

 untenable. 



The next expression of opinion on this sub- 

 ject was made by myself in describing the 

 osteology of Patriofelis. In this publication 

 I pointed out the large assemblage of ereodont 

 characters to be found in the skeletons of 

 modern pinnipeds and from a careful analysis 

 of these features in comparison with those 

 of certain members of the Creodonta I was 

 led to the conclusion that the seals are the 

 direct descendants of the creodonts. I fur- 

 ther held that the particular family among 

 the latter which exhibits the closest approxi- 

 mation and furnishes the most likely ancestral 

 beginnings thus far known is the Oxysenidse, 



Osborn, followed by Matthew and Scott, 

 has dissented from this view and failed to dis- 

 cover any relationship between the creodonts 

 and pinnipeds. Osborn's argument against 

 the hypothesis was based wholly upon an 

 effort to disprove the supposed aquatic or 

 semiaquatic habits of certain of the Oxysenidse, 

 which he concluded were preeminently ter- 

 restrial or arboreal. Matthew's argument 

 consists of a simple denial of the alleged re- 

 lationship of the two groups. It now re- 

 mains to reexamine the subject in the light 

 of this newly acquired evidence and test the 

 hypothesis of a ereodont ancestry by this old- 

 est and most primitive pinniped thus far 

 discovered. 



The specimen consists of a fairly well pre- 

 served skull in which the larger part of the 

 dentition, especially that of the upper jaw, 

 is present. The most important feature of 

 the teeth is the evidence they afford of their 

 derivation from a former more complex or 

 tubercular condition. This is especially 

 marked not only by the two- and three-rooted 



