Key to the Species, 
A. General colour black. 
Larger; culmen over 60 mm. 
a'. With white markings on the head and 
throat . . . . . . . . . . P. 
h'. The white markings confined to the throat 
6. Smaller ; culmen under 50 mm., no white 
markings on head or throat 
B, General colour grey above, white below . . 
a. conspicillata, p. 108. 
P. a. steadi, p. 114. 
P. parhinsoni, p. 116. 
P. cinerea, p. 119. 
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