662 BULLETIN 50, UNITED STATES NATIONAL MUSEUM.- 
Birds, 1881, no. 678; Man. N. A,. Birds, 2d ed., 1896, 583.—Lucas, Proc. 
U.S. Nat. Mus., xiii, 1891, 130 (osteology).—AMBRICAN ORNITHOLOGISTS’ 
Unron Commirrer, 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).—Townsenp (C. H.) 
Bull. Mus. Comp. Zool., xxvii, 1895, 125 (Malpelo I., off Bay of Panama).— 
Roruscump and Hartert, Novit. Zool., vi, 1899, 89 (Culpepper I., Gala- 
pagos).—Swoperass and Hetzer, Proc. Wash. Ac. Sci., v, 1904, 237 (Chat- 
ham, Hood, Seymour, James, Albemarle, Narborough, Tower, Wenman, and 
Culpepper islands, Galapagos; Malpelo I.; habits; descr. eges).—GIFFORD, 
Proc. Calif. Ac. Sci., 4th ser., ii, pt. i, 1913, 35 (Albemarle, Brattle, Cham- 
pion, Charles, Chatham, Cowley, Crossman, Culpepper, Dalrymple, Daphne, 
Delano, Enderby, Gordon, Guy Fawkes, Hood, Indefatigable, James, 
Kicker, Narborough, Seymour, Tower, and Wenman islands, Galapagos; 
habits, etc.). 
C[reagrus] furcatus Rorascump and Harter; Novit. Zool., vi, 1899, 109 (Wen- 
man I., Galapagos). 
Creagrus furcalus RoruscHitp and Hartert, Novit. Zool., vi, 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 Leacu, in Ross’s Voy. Baffins Bay, 1819, App., lvii. (Type, by 
monotypy, Larus sabini Sabine.) 
Chema® (emendation) RetcHenow, Journ. fiir Orn., April, 1889, 188. 
Small Laride (wing 260-286 mm.) with tail less than half as long 
as wing, slightly or moderately forked, exposed culmen decidedly 
shorter than tarsus, and bill deepest at gonydeal angle, not decurved 
terminally. 
Bill much shorter than head, the exposed culmen about as long as 
middle 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 
rounded 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 
@Xyun, yawning, gaping. (Richmond:) 
