424 SULID.U. 



Key to the Species. 



I. Feathering on the throat cleft and extending 

 forward in a double point between the rami 

 of the mandible as far as the notch in the 

 npper mandible ; a naked band down the 

 middle of the throat. 



A. Plumage mostly white ; head and neck 



washed with ochraceous buff. {Adults. ) 



a. Naked band on throat about 2 inches 



in length and not continued down the 



fore-neck. 

 «'. All the tail-feathers pure white .... bassnna, p. 425. 

 b'. Two middle pairs of tail-feathers 



sooty-black, four outer pairs white . . serrator, p. 428. 



b. Naked band on throat continued down 



the middle of the fore-neck and nearly 



6 inches in length '. capensis, p. 429. 



B. Plumage mostly dark brown, each feather 



with a white spot at the extremity. 

 {Immature.) 



c. Naked band on throat about 2 inches 



in length and not continued down the , , .„- 



fore-neck Uas.5«««, p. 425 



d. Naked band on throat continued down ' «'''"''«'o''' P- ■*-»• 



the middle of the fore-neck and about 



6 inches in length capensis, p. 429. 



II. Feathering on the throat truncate and with 



an entire margin, falling far short of the 



notch in the upper mandible. 



C. Plumage of the upper parts, as well as 



the head and neck, mostly pure white. 



e. Tail mostly brownish black : outer 



webs of flight-feathers brownish black. 



c'. Bill pale greenish or bluish horn .... cymwps ad., p. 430. 



d!. Bill red variegata ad., p. 434. 



/. Tail pure white, outer webs of flight- 

 feathers hoary grey piscator ad., p. 432. 



D. Plumage of the upper parts dark brown, the 



feathers of the back and scapulars shad- 

 ing into whitish at the extremity. 

 g. Feathers of the head and upper neck 

 narrow and pointed, brown on the 

 basal two-thirds, white along the 

 middle and at the tip ; wing-coverts 



uniform dark brown nebouxi ad., p. 435. 



h. Feathers of the head and neck rounded 

 and pure white, like those of the 

 underparts ; wing-coverts dark brown, 

 fringed with white at the extremity 



like those of the back variegata imm., p. 434. 



E, Plumage of the upper parts uniform deep 

 sooty-brown. 

 i. Head and upper half of neck sooty- 

 brown cyanops imm., p. 430. 



k. Head, neck, and chest imiform deep 



sooty-brown, like the back. , . ,o j Aoa 



, -n i J 1, II u-i sula S X ad., p. 436. 



e . Breast and belly piu-e white { , ^ ■ n, / a An 



" ^ brewstert 2 ad-) P- 440. 



