EASTERN WHITE-WINGED TERN. 
using it to designate the form which breeds in China and wanders southward 
to Java, Celebes, and North Austraha. Series of breeding birds compared 
with similar series from Europe, show that the Chinese birds have more powerful 
bills and longer wings, and of course winter-birds show similar differences. 
When examining the breeding series, I found that the females were distin- 
guished from the males by the tail showing a distinct grey-wash and distinctly 
shorter bills ; the grey wash is more pronounced in the Eastern birds than in the 
Western, but it appears to be a constant feature which has not been previously 
recorded. While this was in the press, Nicoll {Ihis, 1912, p. 453) has inde- 
pendently confirmed this observation regarding the Western form, writing: 
“Females of the present species differ from the males in having less white 
on the shoulders and grey tails, and in being less sooty black below ; whereas 
adult males have pure white rectrices, and are jet black on the under- 
parts.” I also found the wings of the females to be constantly shorter, and 
of course the measurements show similar differences in the winter-plumage, 
but the birds do not then have white tails, as stated by Saunders in his 
Key to the Species in the Cat. Birds Brit. Mus., Vol. XXV. 
315 
