terrestrial Carnivora, but the question is, to which group of Carnivora 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[1] 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]
