PTEROMYS GENIBARBIS. 
parts of the membrane are sooty-brown, diversified with grayish hairs, scattered 
singly, or in tufts ; on the thick lanuginous covering of the posterior extremities, 
the colour is lighter; on the extreme border it is gray. The hairs are whitish, closely 
arranged, and delicate along the cartilage by which the membrane is expanded ; at 
the extremity they form a close fringe, which is continued along the entire lateral 
border of the membrane. On the feet and toes, short, delicate, grayish hairs are 
scattered, not very closely. A greatly enlarged scrotum is a common character of 
the different species of Pteromys ; in our animal, this part is covered with a soft, 
white down. On the lateral parts of the head, between the ears and the termination 
of the neck, the hairs are dispersed in small tufts, alternately of darker and lighter 
shades ; and the separation between the upper and the lower parts is strongly marked 
along the neck and shoulder. 
DIMENSIONS. 
Inches Lines 
Length of the body and head, from the extremity of the nose 
to the root of the tail 8 9 
the tail 5 0 
............... head and neck 3 0 
anterior extremities, from the shoulder to the extremity 
of the claws 3 0 
cartilage supporting the flying-membrane 1 4 
posterior extremities 3 9 
The Pteromys genibarbis presents nothing peculiar in a generic point of view. 
The Javanese species, generally, are distinguished by the length of the cartilage which 
supports the flying-membrane : in two of our species, the tail is compressed, as in 
the Pteromys hudsonius ; in the Pt Petaurista, though it is greatly elongated, this 
organ is cylindrical, as in the common European Flying Squirrels. 
The Pteromys genibarbis is very rarely met with in Java : I obtained a single 
individual only, near the Eastern extremity of the Island, in the same districts 
which also furnished the Delundung and the Tupaia to my collection. The most 
assiduous research in the central districts did not procure me another individual. I 
have reason to believe that the Sciurus Sagitta of Linnaeus, which was probably 
obtained near the Western extremity of Java, is equally rare. The description of 
the latter, contained in the I2th Edition of the Systema Naturae of Linnaeus, on the 
authority of Nordgren, has the character of being carefully made on the spot ; the 
size, the colour, and particularly the continuation of the membrane from the sides 
of the head to the anterior extremities, shew it to be an animal clearly distinct from 
