SEXUAL DIFFERENCES. 



41 



tusks (see fig. 1) is doubtless abnormal, and is doubtless owing 

 to their unsyinmetrical development and overlapping at the 

 points, which must have interfered to some extent with their 

 use, and hence have preserved them from wearing. 



FIG. 1. Odobcenus rosmanis, . 



In the National Museum at Washington a,re also four skulls, 

 which, though unmarked as to sex, are unquestionably those of 



