SQUIBRELS, MAEMOTS AND PIKAS. 75 



Beside the common squirrel there are at least' three species of 

 flying squirrels found in North China, not to mention the ground or 

 striped squirrels and their allies the susliks and marmots. 



Of the flying squirrels two are large species belonging to the genus 

 Pteromys. Both of these were originally described from the forested 

 areas of North-eastern Chihli. They are large rodents with wide, 

 fur-covered membranes stretching along the sides of the body, joining 

 up the front and hind limbs. An elongated bone from the wrist 

 supports this membrane in front, while it also stretches from the back of 

 the hind limbs and embraces the tail. Thus when the animal spreads out 

 its limbs it becomes, as it were, a living parachute, so that it can 

 jump from the top of a tree, and by utilizing the resistance of the 

 air vol-plain a considerable distance, — it is said upwards of forty yards. 



The two species recorded are Pteromys xanthipes and P. melanop- 

 tcrus. The former is of a rich chestnut-red colour with a white 

 head, the latter of a dull grey-brown. 



The Flying Squirrel (Sciuropterus buechneri). 



The third species is much smaller, and belongs to the genus 

 Sciuropterus. This is a pretty little creature, related to the American 

 flying squirrels. It is about the size of the common rat, and has a 

 fine, very soft coat of grey, tinged in places with buff. The underside 

 is grey- white, the cheeks silver-grey. The tail is bushy but flat, 

 the sides being buff, the lower surface black, with a black line down 

 the upper surface. What makes this squirrel one of the most beautiful 

 of its kind are the enormous black eyes. The wing-membrane is not 

 so broad as in the foregoing genus, nor is it continued behind the hind 

 legs. The species was named Sciuropterus buechneri from specimens 

 obtained in Kansu. In the winter of 1909-10 I secured several 



