Descriptions of East Asiatic Mammals 243 
of the head and body is 15 inches, tail ISYo inches, foot 2% 
inches. This form occurs in Tonkin and Laos, as well as in 
Yunnan. 
The Chin Hills Spotted Flying Squirrel, Petanrista sybilla, 
has very few white spots, and the head is red like the back. The 
membrane above is brilliant chestnut. The hands, feet, and tail 
are rufous, the tip of the last with some black hairs. The length 
of head and body is 14 inches, tail 14 inches, foot 2^ 
inches. 
The Hoary Giant Fying Squirrels, members of the P. 
philippinensis section {philippinensis, incidentally, is from India, 
not the Philippines), comprise two species of eastern Asia: 
P. cineraceus of Arakan and northern Siam and P. lylei of 
Burma, Siam, and Tonkin. 
Petaurista cineraceus is drab-colored, grizzled with white, 
the bases of the hairs brown. The underparts are white. The tail 
is gray with the tip black, and the hands and feet are blackish 
brown. The length of the head and body is 18% inches, tail 
22 inches, foot 3% inches. A race, P. c. stockleyi, is distin- 
guished in northwestern Siam. 
Petaurista lylei is hoary, with the dorsal hairs brown washed 
with white, the bases of the hairs dark gray. The tips of the 
ears are orange-red, a tuft of hair behind each ear black. The 
edge of the flying membrane is orange, the tail black touched 
with red, the underparts rich chestnut, the throat hazel. The 
chin, hands, and feet are black. This Squirrel is found in north- 
ern Siam. The length of the head and body is from 18 to 20 
inches, tail 23 inches, foot 3% inches. A race of lylei from the 
south Shan States, P. I. venningi, has the undersurface browner, 
less reddish. Another race, from Tonkin, Laos, and Annam, 
P. I. badiatits, is less hoary, and has the flying membrane almost 
wholly rufous. 
The White-backed Giant Flying Squirrels, relatives of 
P. albiventer of Nepal, comprise several species : P. annamensis 
