THE SPECIES OF THE GENUS. 21 



the T. rosmarus, and they curve downward, outward, and in- 

 ward, instead of continually diverging as in this species. At 

 their emergence from the alveoli the tusks are two and three- 

 quarter inches apart, near the middle five and a quarter inches, 

 and at their tips only one inch. Their length is twenty-two 

 inches and then 1 diameter at the alveolar border antero-posteri- 

 orly two and a quarter inches, and transversely one and a half 

 inches. Towards their lower part they are twisted from within, 

 forwards and outwardly." After quoting Pennant's remark 

 (already given, see p. 17) about similar differences noted by him, 

 he adds that "the superior incisor and molar teeth are also very 

 much smaller than in the fossils of T. rosmarus," and he gives 

 measurements showing this difference. He then says : " The hairs 

 of the upper lip of the T. rosmarus are stated by Shaw, to be about 

 three inches long, and almost equal to a straw in diameter.* In 

 the specimen under consideration, the hairs of the moustache 

 are stiff-pointed spines, not more than one line long at the upper 

 part of the lip, and they gradually increase in size until at the 

 lower and outer part of the lip they are about one inch in length." 

 He further adds, in the same connection : " Since presenting the 

 above communication to the Society, the Academy has received 

 from Mr. Drinker, of Canton, an entire specimen of the Walrus 

 from Northern Asia. In this individual, which measures in a 

 straight line eight feet from the nose to the tail, the tusks are 

 ten inches long, and diverge from their alveoli to the tips, where 

 they are five and a half inches apart, but they are slender, as in 

 the stuffed head above mentioned, and appear as if they would 

 ultimately have obtained the same length and direction. Per- 

 haps the peculiarities noticed may prove to be of a sexual char- 

 acter."t 



As will be shown later, we have here the more prominent ex- 

 ternal differences characterizing the two species of Walrus for 

 the first time explicitly stated from direct observation of speci- 

 mens. If Dr. Leidy had had at that time good skulls of the 

 two species for comparison, the other important cranial differ- 

 ences (noted beyond) could not have escaped him, and he per- 

 haps would have been led to formally recognize the Pacific Wal- 

 rus as a species distinct from the Atlantic Walrus. 



I have met with nothing further touching this subject prior 

 to Mr. H. W. Elliott's report on the Seal Islands of Alaska, 



* "Shaw's Zoology, vol. i, pt. i, p. 234." 



t Trans. Aiuer. Phil. Soc. Phila,., vol. x.i, pp. 85, 86. 



