io8 Field Museum of Natural History — Zoology, Vol. XL 



parts white, the hairs plumbeous gray at base; under surface of tail 



tawny or grayish according to season. 



In winter: Upper parts tawny brown or pale cinnamon brown. 

 Measurements — Total length, about ii in. (278.2 mm.); tail vertebrae, 



1. 12 in. (130.5 mm.); hind foot, 1.45 in. (37.6 mm.). 



The habits of the Northern Flying Squirrel are apparently similar 

 to its more southern relative {S. volans) , with the exception that it is 

 more hardy and does not hibernate in winter. Dr. C. Hart Merriam 

 says: ''The mercury may indicate a temperature many degrees below 

 zero, or snow may be falling in quantities sufficient to obstruct the 

 vision, without seeming in any way to dishearten this merry adventurer. 

 The last rays of the departing sun have scarcely disappeared from the 

 western horizon before the sombre shades that mark the approach of 

 winter night commence to gather about the snow clad forest. Whether 

 bright stars sparkle and shine through a frosty atmosphere, or heavy, 

 leaden clouds overhang the scene, makes little difference to the North- 

 em Flying Squirrel. He emerges from his warm nest, takes a hasty 

 survey of the surroundings lest some wily owl should lurk hard by, 

 glides silently to a neighboring tree, and starts forthwith upon his 

 nightly tour in quest of food and sport." (/. c, p. 206). 



The young number from 3 to 6 and are usually born late in April. 



Specimens examined from Wisconsin and adjoining states: 

 Wisconsin — (M. P. M.) Kelly Brook, Oconto Co., i. (O. C.) Gor- 

 don, Douglas Co., i; Langlade Co., 1 = 3. 

 Michigan — Champion, 3. 



Subfamily SCIURIN^. 

 Genus SCIURUS Linn. 



Sciurus Linnaeus, Syst. Nat., X ed., I, 1758, p. 63. Type Sciurus 



vulgaris Linn. 



Tail long and thickly haired (bushy); eyes large and ears well 

 developed; skull with elongated, pointed (spine-like), postorbital pro- 

 cesses; infraorbital foramen small and confined to the lower portion 

 of maxillary; toes with claws; front toes 5, four well developed but the 

 fifth rudimentary, very small and hardly noticeable; anterior upper 

 premolar when present very small. 



Dental formula: L > C. 5 Pm. j or ? M. - — ^=22 



I-I 0-0 I-I I-I 7,-T, 



or 20. 



