Family XXXI. PERDICINAE. PARTRIDGES.
GENUS I. ORTHYX, Steph. AMERICAN PARTRIDGE

Bill very short, robust, rather obtuse; upper mandible with the outline decurved from the base, the ridge narrow at the base, on account of the breadth of the nasal membrane, somewhat distinct in its whole length, with the sides convex, the gap-line arched, the edges thin, without notch, the tip decurved, thin-edged, obtuse; lower mandible with the angle short and rounded, the dorsal line slightly convex, the sides rounded, the edges involute, the tip rounded. Nostrils basal, linear, operculate, nearly concealed. Head of ordinary size, ovato-oblong; neck rather short; body full. Feet of moderate length; tarsus shorter than the middle toe, with two anterior series of large scales; first toe small and elevated; third very long, second shorter than third, scutellate, connected at the base by webs of a considerable extent. Claws rather stout, arched, compressed, rather acute. Plumage dense, rather compact; wings short, concave, rounded. Tail short, rounded, of twelve feathers. A bare space behind the eyes. Tongue triangular, fleshy; oesophagus with an ovate oblique crop on the fore part of the neck; stomach a very large and strong gizzard, broader than long, placed obliquely, with concave grinding surfaces; intestine long and wide; coeca large.