46 BULLETIN OF THE NUTTALL 



DESCRIPTION OF A NEW DUCK FROM WASHINGTON 

 ISLAND. 



BY THOMAS H. STREETS, M. D., PASSED ASSISTANT SURGEON, U. S. N. ' 



Chaulelasmus couesi. 



Bill nearly as long as the bead, about as deep as broad at tbe 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 G. strepe- 

 rus, anterior portion broad, straight, and flattened. Internal lamella? 

 numerous, small, and closely packed, about seventy-five in number, — 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 brownish-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 extrem- 

 ity, which gives to tbis 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 Avhite ; 

 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 ; third toe, 1.88 without claw, longer 

 than outer toe without claw ; outer toe, 1.75. 



