482 



MAMMALIA. 



to the season, having a summer and winter coat. In Sweden, 

 Russia, and Siberia, it becomes of a fine greyish slate colour 

 under the influence of cold. Its fur at this period acquires value, 

 and is exported in considerable quantities. 



Genera Sciuropterus, Pteromys, and Anomalurus. — The animals 

 divided into these three genera are vulgarly known by the name 

 of Flying Squirrels. Their common character consists in their 

 being provided with wing-like membranes, extending along the 

 flanks between the anterior and posterior members. These 

 membranes are covered with hair like the other parts of the body. 



Vig. :ja7. — Ajlu^ncan i'lyiu^ Squirrels {Hdurupterus volucella). 



and constitute veritable parachutes, which enable them to sustain 

 themselves a little longer in mid-air than the commonalty of 

 animals, and consequently to clear considerable distances at a 

 single bound. 



These, then, are not wings, and of no use for ascent like the 

 wings of Birds, but are only serviceable in descending and 

 moving horizontally. With the exception of this characteristic 

 feature, these three genera of Rodents have absolutely the 

 physiognomy and the habits of the true Squirrels. 



The Sciuropteres (Winged Squirrels), Fig. 207, are the smallest 

 of the flying Squirrels. They inhabit the northern regions of the 

 globe, particularly Russia, Siberia, and North America; and it 



