PTEROMYS GENIBARBIS. 



Between the anterior extremities and the head, no vestige of a flying-membrane 

 appears ; in the Sciurus Sagitta, on the contrary, as described by Linnaeus, the 

 membrane is extended from the head to the wrists. In its expansion, between the 

 extremities, the membrane is bordered by a beautiful fringe, consisting of dehcate 

 hairs, of a hghter colour than the fur of the animal generally, very closely arranged, 

 and diverging in a horizontal or slightly curved direction. This border is more full 

 and compact along the posterior extremities. At the termination of the cartilaginous 

 support near the wrist, it constitutes a delicate broad brush or peniciUus. The feet, 

 as in other species of Pteromys, project beyond the membrane ; the fore-feet consist 

 of four toes, and a very obscure rudiment of a thumb. The toes are slender, com- 

 pressed, and armed with broad, strongly curved, and very sharp claws. The two 

 middle toes are somewhat longer than the exterior, which are nearly of equal length. 

 An elevated, circular, Avarty protuberance exists on the extremity of the first 

 phalanx, above the articulation. On the posterior extremities, the feet are divided 

 into five toes, which are somewhat lengthened, but in other respects agree in cha- 

 racter with those on the anterior extremities. They admit of free motion ; the small 

 toe is nearly as long as the intermediate toes ; the thumb is smaller, and somewhat 

 removed from the other toes. The warty protuberance on the extremity of the first 

 phalanx, is most conspicuous on the small toe. 



The tail equals in length nearly two-thirds of the body of our animal. It is 

 compressed, oblong, somewhat broader in the middle, and truncated at the extremity. 

 The separate hairs which cover it, are arranged loosely, in a distichous manner, or 

 spreading from the middle to the sides ; they are long, delicate, silky, slightly 

 undulated, and numerous, affording to this organ a degree of fulness, which is 

 highly ornamental. 



The general covering of our animal is very beautiful. The fur consists of long 

 hairs, downy at the base, closely arranged on the neck and back, more distant on 

 the flying-iTiembrane. For an animal inhabiting a hot climate, this fur is uncommonly 

 thick ; it possesses indeed the delicacy and fulness of the fur of an animal from the 

 northern regions. Solitary bristly hairs project in many parts from the downy 

 covering. On the under parts the texture of the hair generally is more lax and 

 delicate ; it is woolly on the throat, breast, and abdomen ; on the hypochondriae, 

 and on the flying-membrane, it is loose and straggling. 



The general colour of the fur of our animal is gray on the upper parts, and 

 white underneath ; the head, above, is purely gray ; on the neck, the back, and the 

 tail this colour has a brownish tint, inclining to tawny; the anterior and middle 



