1897.] NATURAL SCIENCES OF PHILADELPHIA. 319 



1. Sciuropterus alpinus (Richciruson). Rocky Mountain Flying Squirrel. 



1828. Pteromys alpinus Richardson, Zool. Jour., (Lond.), Ill, p. 519. 



1829. Pteromys sabrifius var. 3. alpinus Richardson, Faun. Bor. Amer., I, 

 p. 195. 



1854. Pteromys, alpinus Audubon & Bachman, Quad. N. Amer., Ill, p. 206. 

 1877. Sciuropterus volucella, var. hudsonius Allen, Monog. N. Amer. Rod., p. 

 655. 



1881. Sciuropterus volucella, a alpinus Trouessart, Cat. des Mam., p. 67. 



Type locality. — Rocky Mountains, at the sources of the Athabasca 

 River (" Committee's Punch Bowl ") and the Peace River (Smoky 

 River ?), Alberta. 



Geographic distribution. — Main range of the Rocky Mountains 

 between latitudes 40° and 60° (Uintah Mountains to Fort Liard 11 ). 

 Northern and southern limits unknown. 



Habitat. — Dense pine forests of the mountains. 



General characters. — Size, largest of the American Flying Squir- 

 rels, with relatively longer tail, larger, narrower skull, flatter brain 

 case, longer rostrum and nasal bones, shorter postorbital processes, 

 and more massive dental armature than sabrinus. 12 Colors above 

 and below lighter (grayer below, more tawny above), lacking the 

 tawny of underparts and rusty or cinnamon shades of upper parts 

 of sabrinus. 



Color. 13 — (Probably based on Drummond's winter specimens 

 " from the head of Elk River "). " The end of the nose is hair- 

 brown and the fur about the mouth and on the sides of the nose has 

 a dark, smoke-gray color. * * * * The surface of the fur on 

 the back has a yellowish-brown color, without any tendency to the 

 more red hue of the back of Pt. sabrinus. The fur of the throat 

 and belly is a grayish-white, without any tinge of buff color ; the 

 tail has a flat, oblong, oval form, and has a blackish-brown color 

 above, and is merely paler beneath." 



Dimensions. — Of Richardson's type (probably from dry skin) ; 

 total length 336 millimeters; tail vertebras 133 ; hind foot 38. Of 

 Audubon and Bachman's type of alpinus (dry, stretched skin ?) ; 

 total length 342 ; tail vertebra? 133; hind foot 38. Measurements 

 taken by collector from carcass of an adult male, No. 345, Coll. of 



11 Assuming the specimens recorded by Dr. Allen (1. c.) to be typical. 



12 For characters of sabrinus compare Bangs, Proc. Biol.Soc. Wash., 1896, 

 p. 162. " 



13 The color characters of this diagnosis are based wholly on Richardson's 

 description of the types in Fauna Boreali Americana. Audubon and Bach- 

 man's description and plate of alpinus appear to confirm these in every par- 

 ticular. 



