xiv ORIGIN OF MARINE CARNIVORA 449 



terrestrial Carnivora, but the question is, to which group of 

 Garni vora have they the most likeness. The semiaquatic Otter, 

 and the still more thoroughly aquatic (marine) Enhydris, 

 suggest an affinity in that direction. The long body and short 

 legs of the Otter, which is more thoroughly at home pursuing 

 fish in the streams than in waddling clumsily upon the banks 

 of the streams, seem to require but little external change 

 to convert it into a small Seal, while, the long and completely 

 webbed hind digits of Enhydris are even more like those of a 

 Pinniped. The Sea-Lions, in which the external ear has been 

 preserved, and in which the limbs have not become so entirely 

 useless for progression on the land as they have in the Seals, 

 seem to be the intermediate step in the evolution of the latter. 

 This, however, is not the opinion of Dr. Mivart, who, without 

 definitely committing himself on the point, presents some evidence 

 for the assumption that the marine Carnivora are diphyletic. 

 This double origin, however, is not from two groups of the 

 terrestrial Carnivora. Dr. Mivart, in common with many others, 

 holds that the Pinnipedia as a whole are undoubtedly nearer to 

 the Arctoidea than to either of the two remaining sections of 

 the sub-order. One of the most striking structural characters 

 in which they show this resemblance is the brain ; the peculiar 

 Ursine lozenge, already treated of as so distinctive a character of 

 the Arctoidea, is repeated in the Pinnipedia. 



There are, however, other points of likeness which seem rather 

 to point to a Creodont origin. Patriofelis is a genus that from 

 more than one side may be looked upon as a possible ancestor of 

 these animals. The Creodont peculiarity of the vertebrae has 

 already been referred to. It may be added that the facial part 

 of the skull is small in Patriofelis, which appears, moreover, to 

 have had an alisphenoid canal. A very remarkable resemblance 

 lies in the structure of the astragalus. This is not deeply 

 grooved on the tibial facet as it is in Fissiped Carnivora. This 

 might be held to be an instance of degeneration in the aquatic Seals, 

 which do not use their limbs as walking organs. But Professor 

 Wortman * has pointed out that in the Sea-Otter, which is entirely 

 aquatic, the groove exists and is plain. The likeness offered to 

 the Seals by the spreading feet of Patriofelis is noticed under the 

 description of that genus. 2 



1 Bull. Amer. Mus. Nat. Hist. vi. 1894, p. 129. 2 P. 456 Iwlow. 



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