66 British Diving Ducks 
and wings, dull black, finely vermiculated with white ; bill and legs, bluish lead-colour ; 
webs and nail of bill, black. Length, i8 to 20 inches ; wing, 9.25 inches ; tarsus, 1.4 inch ; 
bill along ridge, 2 inches. Irides, rich golden yellow. 
The adult male is somewhat late in assuming its eclipse dress, and seems to require 
to be in good health to attain it, for both Pochards and Scaup which I have kept in 
confinement have not fully changed as the wild birds do. About the middle or end of July 
the adult male passes into a fairly complete eclipse. The whole of the wings, scapulars, 
back, rump, tail, and chest are at once moulted direct to the winter dress, a feature of 
the chest feathers being a broad band of white on the edge of every feather. But an 
intermediate or temporary plumage for July, August, and September is furnished in a 
large number of eclipse feathers for parts of the head, neck, nape, mantle, and flanks. 
The head becomes a dull brownish-black, showing light-grey on the cheeks (due to the 
old winter feathers reaching the extremity of their length). A few white feathers come 
into the lores (showing a distinct affinity to female plumage), the neck assumes a grey 
collar, and the nape and mantle, instead of being black, are filled with new grey and black 
vermiculated feathers similar to those on the back. The flanks, instead of being white 
as in spring and winter, are now filled with white feathers finely vermiculated with brown. 
All these new eclipse feathers are again moulted gradually. From the end of September, 
when the bird is still in eclipse dress, till the end of October new winter feathers are 
constantly coming in and displacing the old ones ; and the full winter plumage is not 
assumed until November. 
The trachea or windpipe of the male is somewhat broad in the upper portion but 
narrow towards the bottom, where it branches into the two bronchial tubes. At that 
point of division is situated the bone-like drum, which is very similar to that of the 
Tufted Duck, but having a larger chamber on the left side. This, too, has a transparent 
skin-opening, divided from top to bottom by an arch of bone. On the right or smaller 
chamber the outer skin is divided by a network of bone in the several smaller pockets. 
The weight of five adult male Scaup, taken December 1891, was 40, 40, 41, 42, and 
42 oz. 
Adult Feinale. — Forehead, lores, and chin, white; head to centre of neck, dark brown, 
and in the case of old females, nearly black ; chest, nape, and mantle, brown ; lower chest 
ribbed with white where it joins the white under parts ; back and scapulars, brown, vermi- 
culated with white ; rump, blackish brown ; tail, brown, with a greyish sheen ; under 
tail-coverts, brown, vermiculated with white ; flanks, alternate rich brown, and white vermi- 
culated with fine black lines ; wings as in the male, only that the upper parts are darker 
and more faintly vermiculated with grey. Length, 18 inches ; wing, 8.75 inches ; tarsus, 
1.33 inch; bill along ridge, 1.83 inch. Bill lead blue and slightly darker than the male; 
feet and legs similar to male, but not so bright. 
Like the female Tufted Duck, the female Scaup Duck has a somewhat distinct 
breeding dress. An adult female which I shot off the nest at Myvatn, Iceland, June 20, 1891, 
has the whole of the body and under parts of white, heavily interspersed with brown feathers. 
The back and scapulars also have a number of brown feathers which appear to be new, and 
the whole general tone of the head, neck, and chest is a richer and warmer brown ; there 
are also a few blackish feathers on the lower edge of the chest shield ; the flanks have also 
