XEMA.
Tail forked; said to resemble Black-headed Gull in habits ; eggs in a depression in moss, dull brownish olive blotched, chiefly at larger end, with distinct dull brown.
Xema sabinii (Sabine). SABINE'S GULL.
j 9 Head, nape and upper throat dark slate separated by a narrow black collar from white lower throat and hind neck ; upper parts pale slate ; outer wing coverts, inner primaries, upper tail coverts, tail and underparts white ; outer primaries black with white tips. Bill black, tipped yellow. Inside of mouth and eye-rim vermilion. Legs and feet blackish grey. In winter, head
and neck white streaked grey. Wing 270-290. Tarsus 30-36. Bill 24-23. 9 generally the smaller. Young : forehead, throat and underparts white ; above grey brown buff tipped ; outer wing coverts and inner primaries white, tip of tail brown.
Preeds.—As far as is known, Spitzbergen, N.E. Siberia (Kolyma district) and Arctic N. America. Circumpolar in distribution, has been met with Franz Joseph Land, Greenland ; occurs in winter occasionally in Europe, on Atlantic and North Sea Coasts.