46 ANATID.E. 



c'. A large fleslij' comb on the base of the [p. 54. 



culmen of the male 7. Sarcidiornis, 



d' . No comb on the base of the culmen of the 

 males. 

 dl' . Head not crested, 

 e^. Bill longer or equal to double the 

 depth at base, 

 e". Bill longer or about the length of 

 the head, 

 e'. Outline of the loral feathering 



at the base of the bill with [p. 59. 



the convexity anteriorly 8. Asarcornis, 



/"'. Outline of the loral feathering 



at the base of the bill straight [p. 61. 



and inclined backwards 9. Ehodonessa, 



/^. Bill shorter than the head, with 

 the outline of the loral feathering 

 at the base of the bill inclined 

 anteriorly ; frontal feathers at the 

 base of the culmen almost in a [p. 63. 



straight line 10. Pteronetta, 



/'. Bill not so long as double the depth 

 at base ; size very small ; young in 

 down with tail-feathers very long 



and stiff 11. Nettopus, p. 64. 



e". Head crested ; young in down with 



tail-feathers long and stiff 12. ^x, p. 72. 



5. PLECTROPTERUS. ^ 



.. Type. 



Plectropterus, Leach, MSS. ; Steph. Gen. Zool. xii. 2, 



p. 6 (1824) P. gambensis. 



Plectrophanes, '■'•Leach'''' (erroref), Griff., Cuv. An. 



Kingd. iii. p. 600 (1829) ; Brandt, Descr. et Ic. An. 



Ross. Nov., Aves, fasc. i. p. 6 (1836) P. gambensis. 



Banr/e. Confined to Africa. 



I feel very doubtful about the number of species to be recognized 

 in the present genus. Perhaps, after all, there is only one species. 

 At present it appears that there are four species or geogra- 

 phical races, aU very difficult to define, chiefly from want of a large 

 series of specimens, properly dated and sexed, from the same locality, 

 which would enable one to understand the variations according 

 to age. 



1. The Abyssinian race (P. ruj^pelli), which extends westwards 

 to some unknown region ; the adult male has a very prominent 

 frontal knob, bare rhomboidal spaces on the sides of the neck, the 

 throat and under tail-coverts white. 



2. An Equatorial race (P. gamhensis), which extends from 

 Gambia and Bissao to Angola and Damara-land, and across to 

 Eastern Africa ; the adult male is similar to that of P. r'l'ippelli, but 

 has a smaller frontal knob ; the throat and under tail-coverts are 

 white as in P. ruppelli. 



