658 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 
[Larus] fuligincsus Sctarzr and Savin, Nom. Av. Neotr., 1873, 148.—SHARPE, 
Hand-list, 1, 1899, 140. 
L{arus] fuliginosus Gray, Gen. Birds, iii, 1846, 654.—Couzs, Birds Northwest, 
1874, 643 (synonymy; range).—Rotuscuip and Harter, Novit. Zool., vi, 
1899, 204 (Galapagos). 
[Leucopheus] fuliginosus Bonararts, Rev. Zool., 1855, 20; Consp. Av., ii, 1857, 
232. 
Blasipus belcheri (not of Vigors) Biasius, Journ..fiir Orn., 1865, 378, part (monogr.). 
[Larus] heermanni (not of Cassin) Gray, Hand-list, iii, 1871, 116, no. 11012, part 
(Galapagos). 
Genus CREAGRUS Bonaparte. 
Creagrus Bonaparte, Naumannia, 1854, 213. (Type, by original designation, 
Larus furcatus Néboux.) 
Medium-sized Laride (wing 390-434 mm.) with deeply forked tail, 
exposed culmen about as long as (sometimes longer than) tarsus, the 
latter not longer than middle toe with claw, and bill deepest at base 
and distinctly decurved terminally. 
Bill nearly as long as head, distinctly decurved terminally, much 
deeper at base than at gonydeal angle; exposed culmen nearly as long 
as (sometimes longer than) tarsus; gonys about half as long as man- 
dibular rami, slightly concave, declinate terminally, its basal angle not 
prominent; nostril with anterior end posterior to middle of maxilla, 
the distance thence to loral or latero-frontal antia about equal to depth 
of bill at base; latero-frontal antia about midway (vertically) between 
mental and malar antiz. Wing long and pointed, the longest primary 
(outermost) exceeding distal secondaries by a little less than five- 
eighths length of wing. Tail nearly half as long as wing, forked for 
about one-third its length, the rectrices (including lateral pair) with 
broadly rounded tips. Tarsus about as long as middle toe without 
claw (usually a little longer, rarely slightly shorter); hallux perfectly 
developed, though small. 
Coloration. Adults with under parts (except. of head and upper 
neck), tail, upper tail-coverts and part of wings immaculate white; 
back, scapulars and most of wing-coverts uniform neutral gray, 
relieved by a white stripe along outer edge of scapular region; head 
and upper neck uniform dark gray or dull slate color fading into pale 
gray on lower neck and chest; a white spot on antero-lateral portions 
of forehead. Young chiefly whitish, including head and neck, but 
head with a dusky spot in front of eye and another on auricular 
region; upper parts largely grayish brown, the feathers margined 
terminally with white, the tail white, each rectrix with a subterminal 
spot of dusky. (No seasonal plumages in adults.) 
Range.—Galapagos Archipelago; occasional or casual on coast of 
Peru and off Gulf of Panama. (Monotypic.) 
The single known species of this genus has by many authors been 
referred to Xema, the type of which also has a forked tail, a dusky 
