PTEROMYS SIBERICUS. MYOXUS. 119 



Pteromys Sibericus. 



Pteromys Sibericus, Desm. Mamm. Sp. 553. 

 Sciurus volans, Linn. 

 The Flying Squirrel. 



Description. — Head rounded ; muzzle short and blunt ; 

 eyes large, prominent ; ears short, rounded ; whiskers 

 black, stiff, as long as the head; the membrane of the 

 sides slightly lobed behind the fore-foot. Pur 'whitish 

 grey on the upper parts of the body, on the lower parts 

 pure white ; the base of the hairs and the wool next the 

 body brown ; along the inner portion of the membrane 

 runs a streak of greyish brown ; the extremities of the 

 feet are white ; the tail, which is more than half as long 

 as the body, is covered with long ashy grey hairs. 



Length of head and body, 6 inches 4 lines ; head, 1 inch 

 8 lines ; tail, without the fur, 3 inches 10 lines. 



Its habits are solitary ; it forms a nest in a hollow tree, 

 where it remains generally during the day, coming out at 

 night to feed on the young shoots, especially of the birch 

 and fir. Climbs with facility, and leaps from tree to tree, 

 assisted by the extension of its skin. The female produces 

 from two to four young in the month of May. 



Inhabits the forests of Lithuania, Livonia, Lapland, and 

 Finland, and is nowhere so common as in Siberia. In 

 Eussia proper, according to Pallas, it is very rare ; less so 

 in the pine and birch forests of the Ural Mountains. 



Genus MYOXUS. 

 Teeth.— Incisors, § ; molars, |=|, simple, the summits 

 marked with transverse ridges of enamel, thus resembling 

 the Eat rather than the Squirrel family. Tail long, some- 

 what bushy, the hairs sometimes distichous; fore-feet with 

 four toes and a rudimentary thumb; hind-feet with five toes. 



