662 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



Bii-ds, 1881, no. 678; Man. N. A,. Birds, 2d ed., 1896, 583.— Lucas, Proc. 

 U. S. Nat. Mus., xiii, 1891. 130 (osteology). — American Ornithologists' 

 Union Committee, Auk, viii, 1891, 88; Check List, 2d ed., 1895, 326 (hypo- 

 thetical list, no. 4); 3rd ed., 1910, 369 (hypothetical list).— Baur, Am. Nat., 

 xxxi, 1897, 783 (rock between Gardner and Hood islands, breeding; Barring- 

 ton Islands; near Seymour Island; Abingdon Island). — Townsend (C. H.) 

 Bull. Mus. Comp. Zool., xxvii, 1895, 125 (Malpelo I., off Bay of Panama). — 

 Rothschild and Hartert. Novit. Zool., vi, 1899, 89 (Culpepper I., Gala- 

 pagos). — Snodgrass and IIeller, Proc. Wash. Ac. Sci., v. 1904, 237 (Chat- 

 ham, Hood, Seymour, James, Albemarle, Narborough, Tower, Wenman. and 

 Culpepper islands, Galapagos; Malpelo I.; habits; descr. eggs).- Giffoku, 

 Proc. Calif. Ac. Sci., 4th ser., ii, pt. i, 1913, 35 (Albemarle, Brattle, Cham- 

 pion, Charles. Chatham, Cowley, Grossman, Culpepper, Dalrymple, Daphne, 

 Delano, Enderby, Gordon, Guy Fawkes, Hood, Indefatigable, James, 

 Kicker, Narborough, Seymour, Tower, and Wenman islands, Galapagos; 

 habits, etc.). 



C[reagrus] furcatus Rothschild and Hartert, Novit. Zool., vi, 1899, 109 (Wen- 

 man I., Galapagos). 



Creagrus furcalus Rothschild and Hartert, No\'it. Zool., Ad, 1899, 107 (at sea 

 north of Culpepper I.). 



Creagrus furcata Anthony, Auk, xii. 1895, 291 (off San Diego, Cal., Apr. 14, 1895). 



Genus XEMA Leach. 



Xema Leach, in Ross's Voy. BafRns Bay, 1819, App., Ivii. (Type, by 



monotypy, Larus sabini Sabine.) 

 Chemaa (emendation) Reichenow, Journ. fiir Orn., April, 1889, 188. 



Small Laridae (wing 260-286 mm.) with, tail less than half as long 

 as wing, slightly or moderately forked, exposed cnlmen decidedly 

 shorter than tarsus, and hill deepest at gonydeal angle, not deciirved 

 termmally. 



Bill much shorter than head, the exposed culmen about as long as 

 midtUe toe without claw, much shorter than tarsus, much deeper at 

 gonydeal angle than at base, the maxilla but slightly decurved ter- 

 minally, the gonys strongly ascending terminally with basal angle 

 prominent. Wing long and pointed, the longest primary (outermost) 

 exceeding distal secondaries by about two-thirds the length of the 

 wing. Tail much less than half as long as wing, forked for not more 

 than length of tarsus, the rectrices (including lateral pair) broadly 

 roimded at tips. Tarsus decidedly longer than exposed culmen, much 

 longer than middle toe without claw. 



Coloration. — Adults with back, upper rump, scapulars and greater 

 part of wings uniform gray; lower neck, under parts, lower rump, 

 upper tail-coverts, tail, and distal portion of greater wing-coverts and 

 secondaries immaculate white; distal primaries black tipped with 

 white; head and upper neck dark gray bordered below by a black 

 collar, in winter white with occiput, nape and auricular region dark 



aXijjuij, yawning, gaping. (Richmond") 



