22 DUSKY DUCK. 
Bill yellowish-green, the unguis dusky. Iris dark brown. Feet 
orange-red, the webs dusky. The upper part of the head is glossy 
brownish-black, the feathers margined with light brown ; the sides of 
the head and a band over the eye are light greyish-brown, with longi- 
tudinal dusky streaks; the middle of the neck is similar, but more 
dusky. The general colour is blackish-brown, a little paler beneath, all 
the feathers margined with pale reddish-brown. The wing-coverts are 
greyish-dusky, with a faint tinge of green; the ends of the secondary 
coverts velvet-black. Primaries and their coverts blackish-brown, with 
the shafts brown; secondaries darker; the speculum is green, blue, 
violet, or amethyst purple, according to the light in which it is viewed, 
bounded by velvet-black, the feathers also tipped with a narrow line 
of white. The whole under surface of the wing, and the axillaries, 
white. 
Length to end of tail 244 inches, to end of claws 26; extent of 
wings 381; bill 2,4, along the back ; wing from flexure 114; tail 4,4 ; 
tarsus 154; middle toe 2,3, its claw 4; ; first toe ;5, its claw %- Weight 
3 lb. 
Adult Female. Plate CCCII. Fig. 2. 
The female, which is somewhat smaller, resembles the male in co- 
lour, but is more brown, and has the speculum of the same tints, but 
without the white terminal line. 
Length to end of tail 22 inches, to end of wings 21%, to end of 
claws 22; wing from flexure 101; extent of wings 34} ; tarsus 2, mid- 
dle toe and claw 24; hind toe and claw 75. 
In this species, the number of feathers in the tail is eighteen, al- 
though it has been represented as sixteen. In form and proportions 
the Dusky Duck is very closely allied to the Mallard. The following 
account of the digestive and respiratory organs is obtained from the ex- 
amination of an adult male. 
On the upper mandible are 43 lamelle; on the lower, 85 in the 
upper, and 56 in the lower series. The tongue is 1,, inch long, with 
the sides parallel and furnished with a double row of filaments, nume- 
rous small conical papille at the base, a median groove on the upper 
surface, and a thin rounded appendage, a twelfth and a half in length 
at the tip. The aperture of the glottis is 7,4, long, with very nume- 
