MAMMALIA. 
109 
and two white ones; belly cream-coloured white; tail grayish- 
black above, chestnut, margined with black, beneath. Inhabits 
Southern Asia. 
Genus 21. — Pteromys. — Cuvier. 
Generic Character. —Incisory teeth ‘j, no canines, grinders s— 
total 22. Head round; ears short and rounded *, eyes large; 
fore feet with four elongated toes, furnished with sharp nails, 
and a rudimentary thumb, having an obtuse nail; hind feet with 
five long toes, much divided, and adapted for seizing; tail long, 
villose; skin of the sides extended from the anterior to the pos¬ 
terior extremities, forming a kind of parachute. 
* With the tail round, and hairs not distichous. 
Pteromys petaurista. — The Sailing Petaurista. 
Plate XXI. fig. 6. 
Fur chestnut colour, the hairs being tipped with white on 
the shoulders; whitish-gray underneath ; thighs red; feet brown ; 
tail blackish, and cylindrical. Inhabits India and the Islands. 
** With the tail depressed, and the hairs distichous. 
Pteromys Sibericus. — Siberian Pteromys. 
Plate XVIII. fig. 12. 
Fur ash-gray above, white underneath ; tail half the length of 
the body. About seven inches long. Inhabits Siberia, Fin¬ 
land, and Lapland. — This is the type of M. F. Cuvier’s genus 
Sciuropterus. 
Section II.—With imperfect clavicles, or none. 
Genus 22 —Hystrix. — Linnaeus. 
Generic Character. —Incisory teeth no canines, grinders |. 
totol 20. The grinders have fiat tops, but furnished with ridges 
of enamel. Head strong, convex; muzzle thick ; ears short and 
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