148 ODOBJENUS OBESUS PACIFIC WALRUS. 



generally more convergent, with much greater inward curva- 

 ture ; the mystacial bristles shorter and smaller, and the muzzle 

 relatively deeper 'and broader, in correlation with the greater 

 breadth and depth of the skull anteriorly. The Pacific Walrus 

 has been supposed to further differ from the Atlantic species 

 by the more naked condition of the skin 5 but this seems to be 

 merely a feature of age, baldness being more or less common in 

 old age to both species. The color of the hair is nearly the same 

 in both. A large old male in the Museum of Comparative Zool- 

 ogy, Cambridge, collected at the Prybilov Islands by Capt. 

 Charles Bryant, is entirely destitute of hair, except around the 

 edge of numerous old scars, and on the breast and ventral sur- 

 face where here and there are patches very thinly clothed with 

 very short hair, hardly sufficient in amount to remove the gen- 

 eral impression of almost complete baldness. The longest mys- 

 tacial bristles are scarcely more than an inch in length, while 

 the greater part barely project beyond the skin. There is an- 

 other similar specimen in the collection of the National Museum. 

 A much younger specimen (a female) in the collection of Prof. 

 H. A. Ward, of Eochester, is as well clothed with hair as is the 

 Atlantic species at the same age, from which the color of the 

 hair does not appreciably differ. The mystacial bristles are 

 somewhat longer than in the above-described very old specimens, 

 but are rather shorter than in the Atlantic species at the same 

 age. Probably in young individuals the bristles are much longer 

 than in the adult, as is the case in the Atlantic species. The 

 chief external difference between the two species appears to 

 consist in the shape of the muzzle and the size and form of the 

 bristly nose-pad, which has a vertical breadth at least one-fourth 

 greater than in the Atlantic species. Yery important differ- 

 ences between the two species are exhibited in the skull, as will 

 be presently described. 



The old male Alaskan Walrus in the Museum of Comparative 

 Zoology has a length as mounted of 3350 mm. (about 10 J feet), 

 and a circumference at the shoulders (axillae) of 3050 mm. The 

 skeleton, as measured while the bones were still connected by 

 cartilage, gave a total length of 9 feet (2646 mm.), of which the 

 skull measured 15 J inches (354 mm.); the cervical vertebra} 

 13 (330 mm.) ; the dorsal vertebrae 45 (1130 mm.) ; the lumbar 15 

 (370 mm.) ; and the caudal 23 (580 mm.). The fore limb, from 

 the proximal end of the humerus to the end of the first or 

 longest digit has a length of 40 inches (1010 mm.), and the hind 

 limb, from the proximal end of the femur to the end of the Ion- 



