288 



U. S. P. R. R. EXP. AND SARVEYS ZOOLOGY GENERAL REPORT. 



Measurements of skulls. 



List of specimens. 



PTEROMYS HUDSONIUS. 



Northern Flying Squirrel. 



Sauna hudsonius, GMEUN, Syst. Nat. I, 1788, 153. 



Pteromys hudsonius, FISCHER, Synopsis, 1825, 365. 



Sciurus sabrinus, SHAW, Gen. Zool. Mamm. I, 1801, 157. 



Ptertmys sabrinus, HIGH. Zool. Jour. Ill, April, 1828, 519. IB. Fauna Bor. Amer. I, 1829, 193. 



WAGNER, Suppl. Schreber, III, 1843, 228. 



AUD. & BACH. N. Am. Quad. Ill, 1853, 202 ; plate cxliii, fig. 1. 

 Severn rivsr flying squirrel, PENNANT, Hist. Quad. II, 1781, 418. IB. Arctic Zool. I, 1784, 122. 



SP. CH. Considerably larger than the P. vdwxHa, or common flying squirrel. Tail considerably shorter than the head 

 and body ; (shorter than the body alone ?) Above, yellowish brown ; beneath, white ; the hair plumbeous at root. 

 Length of head and body about eight inches ; of tail, with hairs, 5J. Hiad foot, 1. 60 inches. 



I regret that the only materials at my command for the description of this species consist of 

 some very imperfect skins. In these the only differences from Pteromys volucella I can realize 

 are the considerably larger size, and the under hairs of the belly, instead of being white at the 

 roots, are lead colored. The tail is proportionally shorter. In almost every respect, however, 

 the one is a miniature of the other. The upper part of the tail is colored like the back, some 

 times with a mixture of darker towards the tip. 



