XVI— MAMMALS OF THE PRIBILOF ISLANDS. 



By Frederick W. True. 



The species of terrestrial mammals of the Pribilof Islands are so few in number 

 that they can scarcely be said to constitute a fauna. We find only a shrew a 

 lemming, and a fox. The first two are closely allied to species on the American 

 mainland, and the fox is supposed to be a late introduction. The islands are com- 

 posed almost exclusively of volcanic materials, but certain fossil remains have been 

 found on St. Paul which are believed by some to indicate that their origin was not 

 entirely volcanic. However that may be, if the present mammals were derived from 

 a preexisting fauna we might properly expect them to differ more than they do from 

 the mainland forms. That they are very closely related would seem to indicate that 

 they are late arrivals from the mainland. The fox, as already stated, is believed to 

 be certainly such, and the same is probably true of the lemming and shrew. 



It is a singular fact, however, that the lemming is confined to St. George Island 

 and the shrew to St. Paul. 



The pinniped carnivora — the fur seal, sea lion, and walrus (now extirpated) — are 

 not peculiar to the islands, and no cetacean is known to frequent their shores 

 exclusively. 



PRIBILOF SHREW. 



" Sorex priiilafensis Merriam. 

 Sorex prihilofensis, Merriam, North American Fauna, 10, December 31, 1895, p. 87. 



This beautiful little shrew is readily recognizable by its peculiar coloration, being 

 grayish sienna brown on the back and abruptly whitish on the sides and belly. The 

 white of the sides is tinged with buff, while that of the under surface is purer.' The 

 chin, throat, and feet are white and the tail is bicolored, brown above and white 

 below. 



Dr. Merriam gives the following average dimensions of five individuals: Total 

 length, 4.13 inches (105'"°'); tail vertebrae, 1.50 inches (34.5'°'"); hind foot, 0.52 inch 

 (13.2'°'").2 



The Pribilof shrew, so far as known, occurs only on St. Paul Island. Mr. Wil- 

 liam Palmer reported in 1890 that the natives considered it very abundant on the 



' There is another American shrew, Sorex riehardsoni, which is sharply tricolored, but this is a 

 species with the under parts dusky and washed into chestnut. 



^Mi. William Palmer's measurements of seven adults give 3.7 inches as the average total length. 



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