Lerwa Hodgs., Mad. Journ. L. & Sci., v, p. 300 (1837).
Type, Perdix lerwa Hodgs.
This genus contains a single species of Snow-Partridge differing perhaps very slightly in size but otherwise constant throughout its range. The wing is short but pointed, the second primary longest, the first and third subequal and very little shorter; in some specimens the first primary is the longest and in others the first three are almost or quite equal; the secondaries are comparatively long, reaching to within about an inch of the wing; the tarsi are short and feathered over half their length in front ; the tail consists of fourteen feathers and is slightly rounded at the end.
The sexes are alike in plumage but the male possesses a spur on the tarsus, generally short and blunt, occasionally well-developed and sharp, whilst, in rare instances, there is an incipient second spur.