History of North American pinnipeds, a monograph of the walruses, sea-lions, sea-bears and seals of North America . y inner anterior angle is also strongly developed, being byfar the most inwardly salient portion of the bulla?, while in theAtlantic skull it is greatly suppressed. As regards the occipitalcondyles, they are broader and shorter in the Atlantic species,and less produced anteriorly. The space between them is also 164 ODOB^ENUS OBESUS PACIFIC WALRUS. considerably broader than in the other, and the plane of artic-ulation is more nearly vertical. This seeins correlate w
History of North American pinnipeds, a monograph of the walruses, sea-lions, sea-bears and seals of North America . y inner anterior angle is also strongly developed, being byfar the most inwardly salient portion of the bulla?, while in theAtlantic skull it is greatly suppressed. As regards the occipitalcondyles, they are broader and shorter in the Atlantic species,and less produced anteriorly. The space between them is also 164 ODOB^ENUS OBESUS PACIFIC WALRUS. considerably broader than in the other, and the plane of artic-ulation is more nearly vertical. This seeins correlate with thegreater incurvation of the tusks; these, being almost verticalin the Pacific species, allow a greater declination of the head. Another .difference apparent in this aspect of the skull is therelative posterior extension of the condylar portion, which, in thePacific species, extends much further beyond the posterior bor-der of the mastoids than in the other. This is obviously due togreater length of the basioccipital segment of the skull in thePacific species, which is clearly shown in the annexed figures. FIG. 26.—Odobccmis rosmarus. (Figs. 26 and 27). The position of the foramina of the basalportion of the skull is also quite different in the two, as isespecially seen in respect to the condylar foramina, which aresituated more posteriorly in the Atlantic species than in theother, due, perhaps, to the shortness in this form of the basi-occipital region. DIFFERENTIAL CHARACTERS. 165 Another difference not yet noted consists in the greaterlength and massiveness of the zygomata in the Pacific species,in which they are fully one-third heavier than in the Atlanticspecies; they being in the former both deeper and thicker.(This is well shown in the above given figures of the skulls asseen in profile and from above and below, but especially asas seen from below.) The orbital fossa? are also quite different,they being relatively long and narrow in the Pacific, and shorterand bro
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