ANATINiE — THE DUCKS — CHAULELASMUS. 



505 



C. slreperus ; Ijut this may very possibly be owing to a difference of age, as the type of Couesi is 

 immature. 



G. Couesi is very distinct, bow-ever, and much smaller, the measurements being as follows : 

 Wing, 8.20 inches; culmen, 1.4(i ; widtli of bill, .55; depth at ba-se, .GO; tarsus, 1.40; middle 

 toe, 1.60.» 



'•S.-^^^ 





C, slreperus. 



' Cn.iULELASMUS CoUEsi, Streets. 



Ckaulelasmus Couesi, Streets, Bull. Nutt. Oru. Club, I. no. 2, July, 1876, 46 (Washington auJ 

 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, ti]) rounded, and unguis abruptly cuiTed ; frontal angle 

 short and obtuse ; dorsal line at first sloping, rather more so than in C. slreperus, anterior portion broad, 

 straight, and flattened. Internal lamellse numerous, small, and closely packed, about seventy-five in num- 

 ber — in slreperus only about fifty. Nostrils sub-basal, lateral, large, and oUong. 



" PlumtKje (immature) ; Head above dark brown, the feathers tipped with a lighter shade; frontal 

 feathers with the centra! portion black, and edged with brownish white ; throat and sides of head brown- 

 ish w^hite, shafts of the feathers brown, a small brown spot at the e.xtremity 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 tlie 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 ; specidum pure white, the inner web of the 

 white feathers graj-ish brown ; in the thu-d feather in the specidunj, 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 featliers, hoai-}' plumbeous g:-ay, 

 under surface lighter and sinning ; under taU-coverts crossed by transverse bars of black and white ; upper 

 coverts composed of dark-brown and black feathers mingled. Under wing-coverts and a.xillars 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. 



" A female is similar, but witli 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 presurae<i, will show the peculiar venuiculated appearance of C. slreperus. 

 They resemble the immature condition of C. slreperus so closely that one description of the coloration 



VOL. I. — 64 



