114 ANSEKES PLECTROPTEKUS 



fl 2 . Size larger, wing over 12 ; an osseous 



callosity on the bend of the wing. 

 a?. Tarsus longer than the middle toe and 

 claw ; lamellae along the upper mand- 

 ible not conspicuous Alopochen, p. 127. 



6 3 . Tarsus about equal to the middle toe 

 and claw ; lamellae along the man- 

 dibles prominent and conspicuous ... Casarca, p. 131. 

 b 2 . Size smaller ; wing under 12. 

 a 3 . Speculum blue or green. 



a- 4 . Bill as long as the head ; tail-feathers 



sixteen to twenty Anas, p. 133. 



6 4 . Bill shorter than the head; tail- 

 feathers fourteen to sixteen Nettion, p. 138. 



b 3 . Speculum salmon - pink ; bill shorter 

 than the head ; tail-feathers fourteen 



to sixteen Pcecillonetta, p. 141. 



ft 1 . Bill spatulate, broadened towards the tip ; 



upper wing-coverts blue Spatula, p. 143. 



B. Hind toe broadly lobed, the breadth of the lobe 

 at least one-third of the length of the toe ; no 

 speculum. 



a. Tail-feathers normal, not narrowed or stiffened Nyroca, p. 146. 



b. Tail-feathers narrowed and stiffened. 



a 1 . Tail short, about one -third the length of 



the wing ; nail of the bill large, and bent 



vertically downwards Thalassiornis, p. 150. 



ft 1 . Tail longer, about half the length of the 



wing ; nail of the bill bent downwards and 



inwards Erismatura, p. 152. 



Genus I. PLECTROPTERUS. 



Type. 

 Plectropterus, Steph. Gen. Zool. xii, pt. 2 p. 6 (1824), P. gambensis. 



Bill long and stout, rather deep at the base, and with a strong 

 nail ; face in front of the eye and on the crown of the head bare of 

 feathers in the adult ; wings with a strong carpal spur ; tail long 

 and rounded, the feathers fourteen in number, broader than in most 

 of the Ducks ; tarsus stout and strong, about the same length as 

 the middle toe and claw, with a row of scutes in front ; hind toe 

 rather long, and with a narrow web below ; plumage glossy ; trachea 

 in the male with a bulb at its base on the left side, surrounded by 

 a bony fenestrated framework. 



Salvadori recognises, rather doubtfully, four species of this 



