68 



NORTH AMERICAN FAUNA 74 



Fig. 46. Comparative lengths of m\'stacial \'ibrissae in captive (upper) and free-living 

 (lower) walruses. Both animals were immature males. (Photos by G. C. Ray and K. W. 

 Kenyon) 



That the vibrissae of wild walruses are kept short by continual abrasion seems 

 to have been recognized first by Allen (1880:29). Nikulin (1941) concluded that 

 the abrasion takes place in connection with feeding, specifically from contact 

 with abrasive bottom materials while the animals dig up mollusks with their 

 tusks. Questioning this, I investigated the abraded surfaces of the vibrissae in all 

 parts of the snout and in specimens of a wide variety of ages. My findings follow. 



