sabine's gull. 721 



Genus XEMA Leach. 



Xema Leach, Ross's Voy. Baffin's Bay, App. p. lvii (1819— Monotype 

 X. sabini). 



Very much like a smaller species of Larus but tail deeply 

 furcated. Two species, X. sabini and X. furcata from Galapagos Is. 



XEMA SABINI 



444. Xema sabini (Sabine)— SABINE'S GULL. 



Larus Sabini Sabine, Trans. Linn. Soc. London, xn, p. 522, pi. 29 



(1818 — Islands near Disco, west coast of Greenland). 



Xema sabinii (J. Sabine), Yarrell, in, p. 573 ; Saunders, p. 657. 



Description. — Adult male and female. Winter. — Fore-head, lores, 

 and crown white ; nape and back of neck and sometimes under 

 and behind eyes brown-black, feathers narrowly fringed white ; 

 lower-neck extending on to upper-mantle white, tinged ash-grey ; 

 rest of mantle, scapulars and back pale slate-grey, lower scapulars 

 tipped white ; rump and upper tail-coverts white ; under-parts 

 including axillaries and under wing-coverts white but coverts 

 along edge of wing with black tips and outer webs ; tail white ; 

 primaries : outer five (2nd to 6th) outer webs and rather greater 

 width on inner webs black, inner portions of inner webs white but 

 not reaching tips which are black with extreme tips white (2nd 

 with very small white tip or no white, rest broad white tips), shafts 

 black-brown, 7th white with proximal three-fourths of outer web 

 black encroaching on to inner web as narrow line, shaft white, rest 

 of primaries white (7th varying somewhat and sometimes much as 

 6th, and sometimes with black spot near tip, 8th sometimes like 

 normal 7th) ; secondaries white, inner ones with part of outer webs 

 slate-grey, which increases on innermost feathers, which have white 

 only at tips ; primary-coverts black, inner ones with small white 

 tips and innermost with white inner web and long white tip ; 

 border of wing including bastard-wing black ; greater coverts 

 slate-grey with long white tips and outer feathers mostly white ; 

 median coverts slate-grey, outer ones with outer webs edged white ; 

 lesser coverts slate-grey, at extreme edge and point of wing white. 

 This plumage is acquired by complete moult Aug.-Dec. Summer. 

 — Another complete moult takes place April-May, sometimes not 

 finished June. Very few in moult examined ; one April moulting 

 primaries in both wings and tail, another April tail but not 

 primaries. As winter but whole head all round dark lead-grey with 

 narrow black ring dividing it from pure white of back and sides of 

 neck and under-parts ; mantle, scapulars, and wing-coverts rather 

 darker slate-grey than winter. 



Nestling. — (Not examined.) Upper-parts deep brownish-buff, 

 crown with irregular black spots, smaller anteriorly, rest of upper- 

 parts irregularly spotted, marbled or clouded blackish ; breast and 

 belly pale dull buff. (Ridgway.) 



vol. 11. 3 A 



