550 BULLETIISr 50, UNITED STATES NATIONAL MUSEUM. 



G[aria] leucoceps Swainson, Cla^sif. Birds, ii, 1837, 373 (Louisiana; based on 

 Mouette brune, de la Louisiane Daubenton, PI. Enl., pi. 997). 



A[nous] leucoceps Gray, Gen. Birds, iii, 1846, 661. 



{'l)Anous melanogenys (not of Gray, 1846) Leotaud, Ois. Trinidad, 1866, 547. 



Anous superciliosus Sharpe, Philos. Trans., clxviii, 1879, 468 (coast of Central 

 America and the Antilles). 



ANOUS STOLIDUS RIDGWAYI Anthony. 



SOCORRO NODDY. 



Similar to A. s. stolidus but coloration slightly darker, the pileuni 

 darker gray, becoming white only on anterior margins." 



Adnlt male.—Wm^, 261.5-292 (272.6); tail, 142-169 (160.5); ex- 

 posed culmen, 41-43.5 (41.9); tarsus, 23-26 (24.6); middle toe, 

 30-34 (31.3).^ 



Adult ftmale.~Wmg, 265-283 (272.6); tail, 141.5-162 (151.1); 

 exposed culmen, 38-43 (40.8) ; tarsus, 23-26 (24.2) ; middle toe, 

 29-32 (30.8).'= 



Pacific coast of Mexico, from Tres Marias Islands and Isabella 

 Island, Tepic, to coast of Guatemala, Socorro Island, Revillagigedo 

 group, Clipperton Island, and Cocos Island. 



Anous stolidus (not Sterna stolida Linnaeus) Sclater and Salvin, Ibis, 1859, 233 

 (Pacific coast Guatemala). — Lawrence, Mem. Bost. Soc. N. H., ii, 1874, 318 

 (Isabella Island, Tepic, n. w. Mexico, breeding; habits; descr. nest and 

 eggs). — Baird, Brewer, and Ridgway, Water Birds N. Am., ii, 1884, 325, 

 part (Pacific coast Central America). — Townsend, Bull. Mus. Comp. Zool., 

 xxvii, 1895, 125 (Cocos Island, Costa Rica; crit.). — Carriker, An. Carnegie 

 Mus., vi, 1910, 415 (Cocos Island). — Gifford, Proc. Calif. Ac. Sci., 4th ser., 

 ii, pt. i, 1913, 24, part (Clipperton and Cocos islands). 



Anous stolidus ridgwayi Anthony, Auk, xv, no. 1, Jan., 1898, 36 (Socorro 

 Island, Revillagigedo group, off w. Mexico; coll. A. W. Anthony); no. 4, 

 Oct., 1898, 316 (Socorro Island).— Neison, North Am. Fauna, no. 14, 1899, 

 26 (Tres Marias, May; Isabella Island, May; between San Bias and Tres 

 Marias; haldts). — Snodgrass and Heller, Proc. Wash. Ac. Sci., iv, 

 1902, 507 (Clipperton and Cocos islands; descr., measurements; habits; 

 descr. eggs). — Mathews, Birds Australia, ii, 1912, 411 (Socorro; Tres Marias). 



[^Inoii^] stolidus subsp. ridgwayi Forbes and Robinson, Bull. Liverp. Mus., ii, 

 no. 2, 1899, 56 (reprint of orig. descr.). 



[^noMs] ridgwayi Sharpe, Hand-list, i, 1899, 137. 



Anous pileatus (not Sterna pileata Scopoli, 1786) Salvin and Godman, Biol. 

 Centr.-Am., Aves, iii, 1903, 661, part, excl. syn. (Isabella, Tres Marias, and 

 Clipperton islands; Pacific coast Guatemala). 



o So far aa the material examined enables me to judge, typical specimens of this 

 form are confined to Socorro, Clipperton, and Cocos islands; at any rate, examples 

 from Isabella island, off Tepic, and from the coast of Guerrero (Sihuatenejo) are in 

 coloration more like A. s. stolidus; in fact, some of them I am not able to distinguish 

 satisfactorily from that form. 



b Nine specimens. 



c Eighteen specimens. 



