ANATIN^ — THE DUCKS — ANAS. 489 



18. Somateria. Feathering at base of maxilla exceedingly irregular, the frontal and loral 

 regions being separated by a backward extension of the bare skin of the maxilla in. the 

 form of an elongated angle or broad lobe. 



d. Bill more or less gibbous at the base, much depressed at the end, which is formed entirely 



by the broad, flat nail ; nostrils usually anterior to the middle of the maxilla. Color 

 black, with or without white on the head or wing, in the male ; dusky grayish brown in 

 the female (CEdemiw). 



19. CEdemia. Feathering on forehead extending only slightly in advance of that on the lores, 

 or only to the base of the gibbosity ; nostrils linear, about the middle of the maxilla. No 

 white in the plumage of either sex. 



20. Melanetta. Feathering on the lores advancing as far forward as that on the forehead 

 (nearly to the nostrils). Bill extremely broad and depressed at the end. Wing with a 

 white speculum. 



21. Pelionetta. Feathering on the forehead extending forward almost or quite to the nos- 

 tril (an inch or more in advance of that on the lores) ; sides of the maxilla greatly swollen 

 in the adult male ; end of bill rather pointed, much narrower than the middle portion. No 

 white on the wing, but head with white patches (indistinct or obsolete in the female). 



e. Bill very broad and depressed terminally, as in the Fidigulece. Tail rather long, graduated, 



the feathers narrow and very rigid, their shafts grooved on the under surface ; tail-coverts 

 very short, scarcely covering the base of the tail (ErismaturecB) . 



22. Erismatura. Nail of the maxilla very small, narrow, and linear, the terminal half bent 

 abruptly downward and backward, so as to be invisible from above. 



23. Nomonyx. Nail of the maxilla large and broad, gradually bent downward terminally, 

 and wholly visible from above. 



/. Bill narrow, sub-cylindrical, terminated by a conspicuous hooked nail, the edges serrated 

 (^Mergece). 

 f. Bill as long as, or longer than, the head, its depth through the base much less than half 

 its length, the serrations prominent. 



24. Mergus. Bill much longer than the head, the serrations acute, curved ; tarsus nearly 

 three fourths the middle toe (with claw) ; crest depressed, or pointed. 



25. Lophodytes. Bill about as long as the head (without crest), the serrations short and 

 conical (viewed laterally) ; tarsus about two thirds the middle toe (with claw) ; crest 

 compressed, with a semicircular posterior outline (when erected). 



/". Bill much shorter than the head, its depth through the base ecj^ual to about half its length, 

 the serrations small and inconspicuous. 



26. Mergellus. Serrations of the bill very fine, conical ; tarsus about two thirds the mid- 

 dle toe ; crest somewhat as in Loplwdytes, but very much smaller. 



Genus ANAS, Linx^us. 

 Anas, Linn. S. K ed. 10, I. 1758, 122; ed. 12, I. 1766, 194 (t3rpe, by elimination, A. boscJias, Linn.). 



Char. Usually rather large-sized Ducks, with the bill a little longer than the head or foot, 

 rather broad, depressed, the edges parallel, the end rounded ; speculum metallic green, blue, or 

 violet, in both sexes, usually bordered posteriorly by a black band, this generally succeeded by a 

 white one. 



Only four species of true Anas are found in America, these being easily distinguished by the 

 following characters : — 



A. Size large (wing not less than 10 inches). 



a. Adult male, except in breeding-season, very different from the female, the plumage varied 

 and brilliant ; secondaries tipped with white, and greater coverts crossed by a subterminal 

 bar of the same. 

 VOL. I. — 62 



