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Show 1885.] DR. ST. G. MIVART ON THE PINNIPEDIA. 485 homogeneous, or whether it may have had more than one source. If the latter question can be settled, it then remains but to inquire from what source or sources the whole group was derived. That the group is subdivisible into three main subgroups has been long recognized. Mr. H. N . Turner, in his classical paper on the foramina of the Base of the Skull *, gives to the group the value of a family, Phocida, which he subdivides and characterizes as follow 2:- Fam. PHOCiDiE. Molars all similar in structure. Subfamily ARCTOCEPHALINA. A postorbital process. An alisphenoid canal; mastoid process strong aud salient, standing aloof from the auditory bulla. Otaria. Ar otocephalus. Subfam. TRICHECHINA. No postorbital process. A distinct alisphenoid canal. Mastoid process strong and salient, its surface continuous with the auditory bulla. Trichechus. Subfam. PHOCINA. No postorbital process. No alisphenoid canal. Mastoid process swollen and seeming to form part of the auditory bulla. Morunga. Lobodon. Cystophora. Leptonyx. Halichcerus. Stenorhynchus. Ommatophoca. Phoca. Professor Flower, in his paper on the Classification of the Carnivora3, says :-"With regard to the group of Seals, which I look upon as essentially belonging to the same ordinal division of the Mammalia as the animals hitherto treated of ji. e. the fissipedal Carnivora], the differences of the cranial characters of the three natural families into which they are divisible, the Otariida, Trichechida, and Phocida, are so well described by Mr. Turner that I need only refer to his paper for them. But I must add that I cannot agree with him when he says, 'I have not seen in the Seals anything which, in m y opinion, warrauts their approximation to any of the other families more than another,' or in his placing them and the three divisions of the terrestrial Carnivora as primary groups of equal value. The differences between the Seals and the terrestrial Carnivora both in teeth and limbs are much greater than any found between different members of the latter group. They should therefore constitute, in m y opinion, a i P. Z. S. 1818, p. 63. 2 L. c. p. 88. 3 See P. Z. S. 1869, PROC. ZOOL. Soc-1885, No. XXXII. 32 |