DUSKY DUCK. 21 
I have represented a pair of these birds procured in the full per- 
fection of their plumage. 
Anas opscura, Lath. Synops. i. p. 545.—Ch. Bonaparte, Synopsis of Birds of the 
United States, p. 384. 
Dusxy Duck, Anas osscura, Wils. Amer. Ornith. vol. viii. p. 141. pl. 72. fig. 5. 
Dusxy Ducx, Nuttall, Manual, vol. ii. p. 392. 
Adult Male. Plate CCCII. Fig. 1. 
Bill about the length of the head, higher than broad at the base, 
depressed and widened towards the end, rounded at the tip. Upper 
mandible with the dorsal line sloping and a little concave, the ridge at 
the base broad and flat, towards the end broadly convex, as are the 
sides, the edges soft and thin, the marginal lamella about forty on each 
side; the unguis obovate, curved, abrupt at the end. Nasal groove 
elliptical, sub-basal, filled by the soft membrane of the bill; nostrils 
sub-basal, placed near the ridge, longitudinal, elliptical, pervious. Lower 
mandible slightly curved upwards, flattened, with the angle very long, 
narrow, and rather pointed, the lamellz about sixty. 
Head of moderate size, oblong, compressed; neck rather long and 
slender ; body full, depressed. Feet short, stout, placed a little behind 
the centre of the body; legs bare a little above the joint; tarsus short, 
a little compressed, anteriorly with small scutella, externally of which 
is a series continuous with those of the outer toe, laterally and behind 
with reticulated angular scales. Hind toe extremely small, with a 
very narrow membrane ; third toe longest, fourth a little shorter, but 
longer than the second ; the scutella of the second and third oblique, of 
the outer transverse ; the three anterior toes connected by reticulated 
membranes, the outer with a thick margin, the inner with the margin 
extended into a slightly lobed web. Claws small, arched, compressed, 
rather obtuse, that of the middle toe much larger, with a dilated, thin 
edge. 
Plumage dense, soft, and elastic ; on the head and neck the feathers 
linear-oblong, on the other parts in general broad and rounded. Wings 
of moderate breadth and length, acute; primaries narrow and taper- 
ing, the second longest, the first very little shorter ; secondaries broad, 
curved inwards, the inner elongated and tapering. Tail short, much 
rounded, of eighteen acute feathers, none of which are reserved. 
