448 Mr. P. W. Frohawk on Sexual 



marked that it appears strange that the difference should 

 have hitherto remained unnoticed. 



I have recently had ample opportunities of observing these 

 birds, and have shot several for the purpose of study. 



When sketching a tine male with the wings expanded, I 

 was so much struck with the remarkable roundness and 

 breadth of the primaries that I was led to dissect other 

 specimens, with the result that I found those with the 

 rounded wings to be males and those with comparatively 

 narrow wings females. I only noticed this marked variation 

 at the end of February, so had but little time to shoot 

 examples for further study. I mentioned the peculiarity, 

 however, to Mr. Castang, and with his kind assistance was 

 enabled to look over many specimens in Leadenhall Market, 

 the result being that the sexes were easily determined by the 

 form of the wing. 



The shapes of the expanded wings are very dissimilar, as 

 will be seen from the drawings (text-figs. 5, 7), both of which 

 are taken from adult birds shewing no light buff edges to the 

 feathers, shot in February 1904. In the male, the primaries 

 are long and broad, giving a decidedly curved outline, while 

 the secondaries, being considerably shorter, add greatly to the 

 rounded appearance of the wing. 



The margin of the expanded wing of the female forms a 

 continuous line, the primaries being much shorter and 

 giving the wing a comparatively narrow appearance. 



The following is the sexual wing-formula: — 

 Text-tig. 6. — £ . 3rd primary longest. 



2nd and 4th primaries equal. 



1st primary = 7th. 



7th, 8th, and 9th primaries lj in. longer 



than in $ . 

 7th primary 1£ in. wide — this being the 



average width of the inner primaries. 

 10th primary f in. longer than the 1st 

 secondary. 

 The secondaries gradually diminish in length on nearing 

 the base, giving a somewhat concave outline. 



