SUBFAMILY ANATINM 



This group includes the so-called Surface-feeding Ducks. In addition to the more 

 typical ducks, it comprises several slightly aberrant or specialized forms such as 

 Nesonetta and Malacorhynchus, as well as others whose position is perhaps more or 

 less annectant between this and other groups. Such are the Sheldrakes, whose gen- 

 eral appearance and habits are somewhat suggestive of the geese; the Mandarin and 

 the Carolina Ducks, by some placed with the Plectropterinoe, but probably more 

 nearly allied to the typical ducks; and finally the peculiar Stidonetta and Heteronetta, 

 isolated forms of the Southern Hemisphere. The members of the subfamily agree 

 with the Diving Ducks (subfamily Fidigidinoe) in having the lower part of the tarsus 

 scutellate, but differ from them in having the swimming membranes of the feet less 

 developed and the hind toe without the marked lobe of these latter. They have 

 rather flattened beaks, and the males nearly always have an asymmetrical osseous 

 bulla at the base of the trachea whose effect seems to be to modify the voice in this 

 sex. 



Although a great number of genera have been currently recognized by various 

 writers, yet in considering the group as a whole it becomes exceedingly difficult to 

 find adequate characters on which to base many of these. A somewhat conservative 

 course has therefore been adopted in this work, and only the following are given 

 generic rank, the chief diagnostic characters of which are grouped in the key ap- 

 pended : 



a. Lower portion of tarsus with transverse scutellae in front; males with an osseous bulla at the base 

 of the trachea; hind toe without a conspicuous membranous lobe. 



b. Edges of bill without prominent lamellae; size larger Alopochen. 



b'. Edges of bill provided with more or less prominent lamellae, 

 c. A wing speculum present. 



d. Tail feathers broad and rounded at the ends, 

 e. Nail of the beak hooked. 



f. Nail narrow, less than one-half the width of bill at tip. 



g. Bill at base deep as compared to width, flat and broadening toward 

 tip; lamellae of upper mandible strongly developed, especially to- 

 ward tip, those of lower mandible projecting strongly outward. 



Tadorna. 



I.' Nail broad, occupying whole tip of beak. 



h. Feathering at sides of upper mandible forming almost a straight line 

 from forehead to angle of mouth; feathers of sides of neck in male 

 elongated; innermost tertial very broad, its shaft bent down. . .Aix. 

 h'. Base of upper mandible forming a deep reentrant angle between 

 feathering of forehead and that of lores; inner tertials somewhat 

 broadened, but the shafts straight Lampronessa. 



