168 



ODOBiENUS OBESUS PACIFIC WALRUS. 



edge, and the process itself lias an inward cnrvature not seen 

 in the other (Figs. 33 and 35). 



The cranial differences here detailed as obtainittg between 



the Atlantic and Pacific 

 Walruses are borne out by 

 a large series of the skulls of 

 the two species, numbering 

 not less than twelve to fifteen 

 of each. There is in each spe- 

 cies a considerable range of 

 individual variation; but the 

 differences presented by the 

 skulls here figured fairly rep- 

 resent average conditions. 

 The only exception to be 

 made is in respect to the 

 tusks of the Pacific speci- 

 FiG. 32. Odohcenus rosmarus. Young, men figured, which are per- 

 haps above the average in size, while they are remarkably di- 

 vergent, more so than in any other specimen of this species 

 that I have seen. Ordinarily, or as a^ rule^ they are more or 



less convergent, and some- 

 times even meet or overlaj), 

 while in the Atlantic species 

 they are, as a rule, (Zivergent. 

 While in the Pacific sxDecies 

 the tusks descend almost ver- 

 tically, in the Atlantic spe- 

 cies they are quite uniformly 

 strongly incurved. 



In view of the differences 

 in the skulls here described, 

 together with the correlating 

 differences of facial expres- 

 sion, notwithstanding the ab- 

 sence of other very strongly 

 marked external differences, I have little hesitation in accord- 

 ing to these two forms specific rank. Added to these differ- 

 ences is the fact of their unquestionably long geographic 

 separation. Whether an individual of one species may not oc- 

 casionally find its way to the habitat of the other is a question 

 for future consideration. That such an occurrence is not impos- 



FiG. 33. Odobcenus obesiis. Youns;. 



