Key to the Species. 
Summer-plmnage. * 
A. Forehead and top of head black . . S. dougallii gracilis, p. 358. 
B. Forehead white ; top of head black .. 8. striata melanorhyncha, p. 366. 
G. Forehead and top of head white ; nape 
black . . . . . . . . .. 8 . sumatrana hempi, p. 370. 
Immature plumage.^ 
A. Small ; wing under 230 mm. 
Forehead whitish ; head and nape dull 
brownish-black . . . . .. 8. dougallii gracilis, p. 368. 
B. Large ; wing over 260 mm. 
Generally darker than the preceding . . 8. striata melanorhyncha, p. 366. 
C. Least ; wing about 200 mm. 
Forehead and head white ; nape dull 
brownish black. .. . . ..8. sumatrana Jcempi, p. 370. 
\ 
* In the winter-plumage the black is mixed with white, otherwise the Key applies, 
t This innnature-plumage seems to last for some time. 
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