318 Mr. J. H. Gurney’s Notes on 
South-American specimen is preserved in the British Mu- 
seum : both these birds are, from the character of the barring 
on the tail, evidently immature ; but I saw, some years ago, 
in the museum attached to the Zoological Gardens at Ant- 
werp, a specimen said to be from ‘ La Plata or Paraguay,” 
which, though similar in its general coloration to those just 
mentioned, had but one white transverse bar apparent on the 
tail, and was therefore an older bird, and probably adult. It 
is, however, possible that, at a still greater age, these choco- 
late-coloured melanistic specimens may assume a blackish 
slate-coloured hue, as has been suggested by Professor 
Schlegel, and as habitually happens in the melanistic males 
of Montagu’s Harrier (Circus cineraceus). 
A less abundant and even more remarkable species than 
Regerhinus uncinatus is its nearly allied congener, R. mega- 
rhynchus. Myr. Sharpe gives as the habitat of this species 
Peru and Bolivia; and in Peru it appears to be found to the 
exclusion of R. uncinatus, but it also occurs in other coun- 
tries where R. uncinatus is likewise found. Thus Messrs. 
Salvin and Godman possess a specimen from the upper 
Amazons and another from Bahia, and in the Norwich 
Museum two examples are preserved from the Isthmus of 
Tehuantepec in South-Western Mexico*. 
R. megarhynchus seems to differ from R. wncinatus only in 
being, on the average of specimens, a slightly larger bird, 
and in being ae furnished with a conspicuously 
larger bill. 
In illustration of the i comonionate dimensions of the two 
species, | may mention that I have taken measurements 
from twenty-one examples of R. uncinatus, with the following 
results, viz.:—The wing-measurement I found to be 10°8 
* One of these Tehuantepec specimens was collected at Santa Efigenia 
by Professor Sumichrast, who does not appear to have recognized the dis- 
tinctness of this species from R. wncinatus, of which I have also seen a 
specimen from Tehuantepec ; it is therefore probable that the Professor's 
note on R. uncinatus, as observed in that locality, which was published 
by Mr. Lawrence in the ‘ Bulletin of the U.S. National Museum,’ No. 4, 
p. 43, may partly apply to R. megarhynchus, 
