318 PROCEEDINGS OF THE ACADEMY OF [1897. 



matches specimens of the same race from nearby localities on the 

 Pacific Coast of British Columbia and Washington. The original 

 description of Bachman, as well as the plate of Audubon and Bach- 

 man, are very fairly diagnostic of oregonensis except the part re- 

 lating to the size and shape of the ears and of the flying membrane, 

 in which latter character of Sciuropterus both Bachman and Rich- 

 ardson were misled by the distorted condition of dried specimens in 

 a bad state of preservation and wholly lacking reliable measure- 

 ments. 



To my knowledge no other names than those already treated of 

 have been proposed for the Sciuropteri coming within the scope of 

 this paper. In the following synopsis I have recognized alpinus as 

 the type of a western group, distinct from the eastern species and 

 separable into four subspecies, alpinus of the eastern Rocky Mount- 

 ain districts, oregonensis of the Pacific Coast lowlands, fidiginosus 

 of the Cascade Mountains, and californicus of the southern Sierra 

 Nevada range. 



I have been unable to examine any specimens from large areas 

 undoubtedly tenanted by this genus, the most noticeable Jack being 

 from the United States east of the Cascade Range and the more 

 northerly coasts of Alaska. It is probable that the form recorded 

 from Cook's Inlet, Alaska, by Turner, 9 will prove separable from 

 oregonensis, as also the form represented by a badly preserved spec- 

 imen from Fort Crook, Shasta County, California, which indicates a 

 smaller race than californicus paler than oregonensis. 10 There is lit- 

 tle doubt also that the southern Rocky Mountains will furnish 

 another race separable from typical alpinus and its more western 

 allies. 



No sexual color differences in our Flying Squirrels are apparent. 

 If any difference in size, the series of skulls and skins show that the 

 largest specimens are females, and these outnumber the males nearly 

 two to one. 



The color differences between winter arid summer pelage in the 

 a! 'pi n ns group are not great, after the molt has been fully effected. 

 It consists in the shorter, coarser, duller haired aspect of the sum- 

 mer coat as compared with that of winter and in the shortening of 

 the colored tips and consequent darkening of pelage due to the ex- 

 posure of the plumbeous bases of hairs. 



9 Cont. Nat. Bist. Alas., 1886, p. 204. 



10 Cooper, Proc. Cal. Acad. Sci., 1N(38, p. 4, records a Flying Squirrel from 

 Mendocino Co., Cal., which represents the southern extreme of oregonensis. 



