'J 8 



EDWARD A. WILSON. 



white and five dark, and in the average of the bill and wing measurements given lielow 

 the advantage in size is always slightly with the white variety. 



This, one might think, could hardly have been accidental, but as three of the 

 darker specimens were females, and all the white were males, the figures were not 

 conclusive, and continuing the measurements to include birds in the collections of the 

 British Museum, as the following table shows, the advantage in size is found to be 

 not invariably with the white variety : — 



