Q3^ BfRDS OF THE GALAPAGOS ARCHIPELAGO— RTDGWAY. vol.xix. 



Genus CREAGRUS, Bonaparte. 

 CreaijrKH, HoXArAiMK. Niiiimaimia, 185 J, p. 213. Type, Lariis furcntns, N(>bonx. 



Generic churaclers. — Bill witli culnieii loiijuer than middle toe (nearly 

 efpial to tarsus), its tip strongly decurved and its depth greatest at 

 base; tail nearly lialf as long as wing, forked for about one tliird its 

 length. Adult with head and upper half of neck slate color, and 

 exterior margin of scapular region bordered by a conspicuous white 

 strii)e. 



Range. — Galapagos Archipelago, Malpelo Island, and (casually) 

 coast of South America as far south as Paracas Bay, Peru. 



This genus is exceedingly distinct from Xema^ the few resemblances 

 to which are i^urely superflcial. 



From Xema^ the points of structural difference are many and decided. 

 The bill is very peculiar in sha])e, being much deeper at the base than 

 elsewhere and strongly decurved at the tip, that of Xema being much 

 smaller proportionally, much straighter, and much deeper through the 

 angle than at the base. The tail is relatively much longer and much 

 more deeply forked, being nearly half as long as the wing and forked 

 for about one-third of its length, while that of Xema is much less than 

 half as long as the wing and forked for not more than one-eighth of 

 its length. As to coloration, there is even greater difference, Crear/rus 

 having the dark ''hood'' descending much farther down over the neck, 

 and instead of being very abruptly terminated by a black border has 

 no very definite outline except on the fore neck; while the white patch 

 at the base of the upper mandible and the very conspicuous white 

 stripe margining the exterior scajjulars are entirely peculiar features. 

 ]Moreover, the plumage of the young is quite distinct in its character 

 from that of Xema. 



CREAGRUS FURCATUS (Neboux). 



Mouette a queue fonrclie, Ni^^BOUX, Eev. ZooL, 1840, p. 290. 



Larus furcaius, N^Borx, Eev. Zool., 1840, p. 290; Toy. V<^nus, Atlas, ISlfi, pi. X. 



("Monterey, California;" Paris Museum). — Prkvost et Des Murs, Voy. 



V^nus, V, Ois., 185.5, p. 277. 

 Crear/rtts/Krca/H.'?, BoNAP.\RTE, Kaumannia, 1854, p. 213. — Salvix, Trans. Zool. 



Soc, IX, Pt. IX, 1876, p. .506 (Dalryuiple Eock, Chatham Island, Galapagos 



Archipelago).— EiDGWAY, Proc. U. S. Xat. Mns., XII, 1889, p 117 (Dal 



rymple Eock). — Townsend, Bull. Mus. Comp. Zool., XXVII, 1895, p. 125 



(Malpelo Island). 

 Xema furcatu8, Burcn, Jour, fiir Orn., 1853, p. 103. 

 Xema f ureal um, CouEs, Key, 1872, p. 317. — Sacndeus, Proc. Zool. Soc, 1878, p. 



210 (Chatham Island); 1882, p. 523. pi. 34 (Paracas Bay, Peru). 

 Xema furcata, CouEs, Check List, 2 ed., 1882, No 791. — Maihd, Hkkweh and 



EinowAV, Water Birds N. Amer., II, 1884, p. 273. 



Specific characters. — Adult with head and neck slate colored, with a 

 white s})ot at base of maxilla and on chin, sometimes also a smaller 

 spot at apex of malar feathering; above clear gray, with a white line 



