ANATHSLE — THE DUCKS — CHAULELASMUS. 
505 
0. streperus ; but this may very possibly be owing to a difference of age, as the type of Couesi is 
immature. 
G. Gouesi is very distinct, however, and much smaller, the measurements being as follows : 
Wing, 8.20 inches ; culmen, 1.40 ; width of bill, .55 ; depth at base, .60 ; tarsus, 1.40 ; middle 
toe, 1.60. 1 
U. streperus. 
1 Chaulelasmus Couesi, Streets. 
Chaulelasmus Couesi, Streets, Bull. Nutt. Orn. Club, I. no. 2, July, 1876, 46 (Washington and 
New York islands, Fanning Group) ; Bull. U. S. Nat. Mus. no. 7, 1877, 21 (do.). 
“ Bill nearly as long as the head, about as deep as broad at the base, depressed anteriorly, sides nearly 
parallel, but converging slightly toward the base, tip rounded, and unguis abruptly curved ; frontal angle 
short and obtuse ; dorsal line at first sloping, rather more so than in C. streperus, anterior portion broad, 
straight, and flattened. Internal lamellaj numerous, small, and closely packed, about seventy-five in num- 
ber — in streperus only about fifty. Nostrils sub-basal, lateral, large, and oblong. 
“Plumage ( immature ) : Head above dark brown, the feathers tipped with a lighter shade ; frontal 
feathers with the central portion black, and edged with brownish white ; throat and sides of head brown- 
ish white, shafts of the feathers brown, a. small brown spot at the extremity of each ; lower portion of 
the neck and breast all around with the feathers marked with concentric bars of black and light reddish 
brown ; under surface of the body white, each feather with a broad dark band near the extremity, which 
gives to this region a mottled aspect ; toward the tail the white of the abdomen assumes a dull reddish- 
brown tinge ; the brownish-red color becomes more decided on the flanks and sides of the body where 
covered by the wings. On the back the plumage is more mature. Color dark brown marked transversely 
by fine wavy lines of black and white ; scapulars dark brown and fringed with a narrow rim of reddish 
brown. Middle wing-coverts chestnut ; greater, velvet black ; speculum pure white, the inner web of the 
white feathers grayish brown ; in the third feather in the speculum, counting from within, the white gives 
place to a hoary gray with a black outer margin ; the primaries light brown, the portion of both webs 
nearest the shaft lighter ; shaft light brown. Tail containing fourteen feathers, hoary plumbeous gray, 
under surface lighter and shining ; under tail-coverts crossed by transverse bars of black and white ; upper 
coverts composed of dark-brown and black feathers mingled. Under wing-coverts and axillars pure white. 
Bill and feet black, somewhat lighter on the inner side of the tarsus. Tibia bare for about half an inch. 
Length, 17 inches; wing, 8 ; tarsus, 1.40 ; commissure, 1.65 ; culmen, 1.45 ; height and breadth of bill 
at base, .55 ; average width of bill, .55 ; first toe, .30 ; second, 1.48, including claw, shorter than third 
toe without claw T ; third toe, 1.88, without claw, longer than outer toe without claw ; outer toe, 1.75. 
“ A female is similar, but with little trace of the peculiar wing markings, both the chestnut and black 
being wanting, and the speculum being hoary gray instead of white. Both the specimens before me are 
immature ; the adults, it is presumed, will show the peculiar vermieulated appearance of C. streperus. 
They resemble the immature condition of C. streperus so closely that one description of the coloration 
vol. i. — 64 
