278 WATER FOWL. 



the banks of streams or the bottoms of shallow creeks, and 

 obtain most of their food by sifting the liquid mud through the 

 lamellae of the bill. 



KEY TO THE SPECIES. 



A. Central upper tail coverts of male re- ) MALLARD. 

 curved. White on wing coverts. J A. boschas. 



B. Central upper tail coverts of male not re- 

 curved. No white on wing coverts. 



a. Sides of head and throat, grayish fulvous, \ DUSKY DUCK. 

 closely streaked with black. ) A. obscura. 



b. Sides of head and throat, pale buff, some- j FLORIDA 

 times streaked with black on cheeks and \ DUSKY DUCK. 

 portions of neck. J A.fulvigula. 



c. Sides of head and throat, buff, streaked j MOTTLED DUCK 



with black. Under parts, mottled with > ., f , 



I A. j. maculosa. 

 buff and blackish brown. 



GENUS CHAULELASMUS 



(Greek x^>*, chaulios, protuberant -f- *Xa<r/>j, 

 elasmos, a plate). 



Chaulelasmus, G. R. Gray. Bon. Consp. List, B. Eur. and N. 

 Am., 1838, p. 56. Type Anas strepera, Linn. 



Bill about two-thirds length of head, longer than tarsus, slen- 

 der, widest at base, greatest width less than one-half the length 

 of culmen. Lamellae of maxilla prominent. Tail pointed, me- 

 dian rectrices not elongated. 



This genus contains the well-known Gadwell or Creek Duck, a 

 cosmopolitan species of the Northern Hemisphere, and possibly 

 a smaller form inhabiting the Fanning Islands in the Pacific 

 Ocean. The male is readily distinguished from other species of 

 North American Ducks by having a great deal of chestnut color 

 on the wing coverts, and the female by her gray and white spec- 

 ulum. 



GENUS MARECA 



(Mareca. Brazilian name for Teal). 



Mareca, Steph. Gen. Zool., vol. xii., 1824, pt. ii.,p. 130. Type 

 Anas penelope, Linn. 



Bill small, tapering toward the tip, nearly half as long as head, 



