22 DUSKY DUCK.
Bill yellowish-green, the unguis dusky. Iris dark brown. Feet
orange-red,, the webs dusky. The uppèr part of the head is glossy
brownish-black, the feathers margined with light brown ; the sides of
the head and band oyer the eye are light greyish-brown, with longitudinal
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 wingrcoyertg 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 speeulum is green, blue,
vioiétj or amethyst purple,according to the light in Which it is viewed,
bounded by velvet-blaek, 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 24^ inches, to end of claws 26 ; extent of
4
5 ;
wings 38^ ; bill 2 j | along the back ; wing from flexure 1 t a i l 4T
tarsus 1 | | ; middle toe 2T
5
4, its claw ; first toe its claw T
2
3, Weight
3 lb.
Adult Female. I'late GCCII. Fig. 2.
The female, which i® somewhat smaller, resembles the male in colour,
but is more brown, and has the speculum of the same tints, but
"without the white terminal linei-
Length to end of tail 22 inches, to end of wings 21 j, to end of
claws 22 ; wing from flexure 10J ; extent of wings 34J ; • tarsus 2, middle
toe and claw ; hind toe and claw fV •
In this species, the number of feathers in the tail is eighteen, although
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 examination
of an. adult male. .„
On the-upper inandibBft are 43 lamellae; 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, numerous
small conical papillae 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 long, with very nume-
DUSKY DUCK. 23
rous minute papillae behind. The oesophagus 12 inches long, of a uniform
diameter of ^ , until fear the lower part of the. neck, where it
enlarges to again ««ltraets ¡is it eaters the thorax, ending in the
proventriculus, which is 1J long, with numerous oblong glandules,
about a twelfth in length. ' Gizzard obliquely elliptical, 2J inches
across, 1A in length, its lateral muscles extremely large, the left if m
thickness,! the right T\ ; their tendons large and strong; the lower
muscle moderately thiek; the cuticular lining firm and rugous, the
grinding surfaces nearly smooth. The intestine, whieh is 5 feet 7i
inches long, is slender and nearly uniform in diameter, measuring A
across in the duodenal portion, £ in the rest; of its extent; the rectum
3 | inches long, dilated into a globular cloaca 1 inch in length, and of
nearly the same diameter. The casca are 6 | long, in diameter for
2 inches of their length, enlarged to in the rest of their extent, and
terminating in an obtuse extremity.
The trachea, moderately extended, is 10 inches long. Its lateral or
contractor muscles are strong, and it is furnished with a pair of cleido
tracheal^, and a pair of sterno-tracheals. The number of rings is 136,
besides 12 united rings forming a large inferior larynx, which has a
transversely oblong bony, expansion, forming on the left side a bulging
and rounded sac. There are 28 bronchial half rings on the; right side,
26 on the left-.,,-