470 
Mr. J. H. Gurney's Notes on 
naturally separated by the totally different character of their 
immature plumage—-the one group, to which I would restrict 
the title of Urubitinga, consisting of U. zonura, U. ant hr a- 
cina, and TJ. gundlachi (if the latter be really distinct), and 
the other, for which I would retain the name of Leucopternis, 
consisting of the remaining species included by Mr. Sharpe 
in his amalgamated genus*. 
Leaving the restricted genus Urubitinga for future consi¬ 
deration, I now propose to make a few remarks on some 
species of the genus Leucopternis, based upon specimens in 
the Norwich Museum, and upon others very kindly lent to 
me by Messrs. Salvin and Godman. 
Commencing with that beautiful species, L. ghiesbreghti , I 
may observe that the proportion of black which mingles with 
the snowy white of its general plumage is greatest in young 
birds, and appears gradually to diminish as their age in¬ 
creases. 
The specimen described by Mr. Sharpe as “ adult " appears 
to me to retain a greater proportion of black in its plumage 
than is the case in some still older specimens; a very adult 
female in the collection of Messrs. Salvin and Godman differs 
from Mr. Sharpe's description in the following particulars : 
the greater wing-coverts are entirely white, and the primary- 
coverts are broadly tipped with white; the primaries are 
white above the emargination, as are the secondaries through¬ 
out, with the exception of a very few sparse and irregular 
remnants of black here and there. 
The specimen figured and described by Du Bus (Esquisses 
Ornithologiques, pi. 1) appears also to be more completely 
adult than that described by Mr. Sharpe. 
As Mr. Sharpe does not mention the first plumage of this 
species, I may add that a decidedly immature example in the 
* Mr. Ridgway, in his recently published and very valuable 1 Studies 
of the American Falconidse/ whilst recognizing the distinction between 
the genera Urubitinga and Leucopternis, includes in the former, at p. 172, 
two species ( schistacea absolutely, and plumbea conjecturally) which I, 
following Mr. Salvin (Ibis, 1872, p. 243), refer to Leucopternis, having no 
evidence that either of them exhibits when young the remarkable imma¬ 
ture plumage which is characteristic of Urubitinga as distinguished from 
Leucopternis. 
