658 BULLETIX 50, UXITED STATES XATIOXAL MUSEUM. 



[Lurus]fuliginosus Sclater and Salyix, Noin. Av. Neotr., 1873, 148. — Sharpe, 



Hand-list, i, 1899, 140. 

 L[arus] fuligiiiosus Gray, Gen. Biid.--, iii, 1846, 654. — Coues, Birds Northwest, 



1874, 643 (synonymy; range). — Rothschild and Hartert, Novit. ZooL, vi, 



1899, 204 (Galapagos). 

 [Leucophseus] fidiginosus Bon.\parte, Rev. ZooL, 1855, 20; Consp. Av., ii, 1857, 



232. 

 Blasipus belcheri (not of Vigors) Blasius, Journ. fiir Orn., 1865, 378, part (monogr.). 

 [Lariis] heennanni (not of Cassin) Gray, Hand-list, iii, 1871, 116, no. 11012, part 

 ^ (Galapagos). 



Genus CREAGRUS Bonaparte. 



Creagrus Bonaparte, Naumannia, 1854, 213. (Tyi>e, by original designation, 

 Larus furcatus Neboux.) 



Medium-sized Laridse (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 terminall}^. 



Bill nearly as long as head, distinctly decurved terminally, much 

 deeper at base than at gomrdcal 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 antise. AYing long and pointed, the longest primaiy 

 (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, tlie 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), tad, 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 witli a dusky spot in front of eye and another on auricular 

 region; upper parts largely grayisli brown, the feathers margined 

 terminally with v/hite, the tail white, each rectrix with a subtcrminal 

 spot of dusky. (No seasonal plumages in adults.) 



Range. — Galapagos Archipelago; occasional or casual on coast of 

 Peru and off Gidf 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 



