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Show 1885.] DR. ST. G. MIVART ON THE PINNIPEDIA. 497 never overlapped by a ridge of bone running from the paroccipital process to the condyle, and never opens into, though it appears sometimes to coalesce with, the foramen lacerum posterius. (7) The glenoid foramen is always very small, and is sometimes not to be detected. (8) The alisphenoid canal may be present or absent, as already mentioned more than once. (9) The suborbital foramen is always rather large; but never as large relatively as in Lutra and Enhydra. It is largest in Trichechus. (10) The frontal postorbital process present in Otaria and Trichechus is never more than a rudiment in the Phocida. (11) The zygomatic postorbital process is formed both by the malar and squamosal in the Phocida, mainly by the malar in Otaria, and entirely by it in Trichechus. (12) The alisphenoid and parietal always join by a narrow process of the latter bone. (13) The premaxillae never ascend to join the frontals. (14) There is never a lachrymal foramen. (15) The basis cranii is nearly always bent, so as to be convex downwards. (16) The anterior nares are quite terminal in Trichechus, rather more distant from the end of the muzzle in Otaria, and not at all terminal, but looking more or less exteriorly upwards as well as forwards, in the Phocida. (17) The opening represents both the foramen rotundum and the spheno-orbital fissure. (18) The optic foramina open into the cranial cavity by a single aperture in Otaria and in Stenorhynchus, but not in the Phocida generally, as in Trichechus. (19) The palate always extends backwards much behind the last molars, but is not commonly narrowed behind save in Otaria. It is not at all so narrowed in Trichechus. (20) Defects of ossification commonly occur in the occipital in the Phocida, but not in Otaria and Trichechus. (21) A preorbital process exists in Otaria and Trichechus; sometimes, but rarely, in the Phocida. (22) The angle of the mandible is inflected (as in Marsupials) in Otaria, but not in the other genera. It is now generally agreed to regard the Pinnipeds as derived from Ursine Arctoids ; and there can be little doubt as to this origin as regards Otaria. But it is not absolutely necessary that the whole Order of Pinnipeds should have had but a single origin. It is at least conceivable that the Otaries might have been derived from Bear-like animals, wbile the Phocida had another, possibly a Lutrine, origin. If this hypothesis were correct, the Pinnipeds would of course" consist of two strains which have gradually grown to be more and more alike. I have no intention of maintaining the probable |