I 



BIRDS OF NORTH AND MIDDLE AMERICA. 489 



coverts and broad tips to secondaries, immaculate white; bill yellow 

 with a broad subterminal band or area of black; iris dark browTi; 

 legs and feet brownish in dried skin (said to be orange-yellow or dull 

 orange in life). 



Adults in winter. — Similar to summer adults, but stripe on side 

 of head more grayish, especially the postocular portion, and (espe- 

 cially in fresh plumage) the silvery frosting on primaries more pro- 

 nounced. 



Immature (young in first winter f). — Similar to winter adults, but 

 under parts pure white instead of pale gray, primaries darker, and 

 bill more dusky or brownish, only the tip being distinctly j'ellow. 



Young. — "The patch before and the streak behind the eye decid- 

 edly larger, and there is an indication of a grajash crescent on the 

 nape; the crown grayish v/hite, slightly mottled with brown, as are 

 the feathers of the mantle; tail-featliers dark ash-gray with white 

 margins; bill yellowish brown at the base, the rest blackish, with no 

 yellow at the tip; tarsi and toes yellow." ^ 



Adult male. — Wing, 264; tail, 140; exposed culmen, 38.5; tarsus 

 22; middle toe, 21.^ 



Coast of southern South America, from Brazil (Rio de Janeiro; 

 Santa Catarina; Sao Paulo) through Uruguay (Maldonado) and 

 Argentina (Estado del Plata; southern Chaco; Punta Lara; Buenos 

 Aires; Ajo; Rancho, breeding; Estancia Espartilla, breeding; Bar- 

 racas al Sud; San Martin; Monte) to Chile (Arica Bay); accidental 

 on coast of New Jersey (Great Egg Harbor), and on Long Island. 



Sterna trudeaui Audubon, Birds Am., fol. ed., iv, 1838, pi. 409, fig. 2 (Great Egg 

 Harbor, New Jersey; type now in coll. U. S. Nat. Mus.?); Orn. Biog., v, 1839, 

 125; S\Tiopsis, 1839, 319.— Gay, Hist. Chile, i, 1847, 484.— Coues, Proc. Ac. 

 Nat. Sci. Phila., 1862, 542 (mongr.); Check List, 1873, no. 571; 2d ed., 1882, 

 no. 802; Birds Northwest, 1874, 675. — Schlegel, Mus. Pays-Bas, vi, no. 24 

 (Stemae), 1864, 29 (Brazil).— Lawrence, Ann. Lye. N. Y., viii, 1867, 299 

 (coast New Jersey). — Landbeck, Anal. Univ. Chile, xli, 1872, 515. — Riug- 

 WAY, Proc. U. S. Nat. Mus., iii, 1880, 208; Norn. N. Am. Birds, 1881, no. 

 684. — Baiuu, Brewer, and Ridgway, Water Birds N. Am., ii, 1884, 290. — 

 American Ornithologists' Union, Check List, 1886, and 2d ed., 1895, no. 

 68; 3rd ed., 1910, p. 44.— Dabbene, Orn. Argent., 1910, 211 (s. Chaco; 

 Estado del Plata). 



a Saunders, Cat. Birds Brit. Mus., xxv, 1896, 131. 



Not\vithstanding that 5. trudcauii in its adult plumages is unlike any other species 

 in coloration, the immature and young plumages resemble very closely those of S. 

 forsteri. The latter may, however, always be distinguished by the darker terminal 

 portion to the inner webs of the lateral rectrices, which are relatively narrower and more 

 elongated, decidedly shorter hallux, and differently shaped bill, which is more slender 

 or at least relatively less deep basally. According to Saunders, the young (which I 

 have not seen) of S. trudeauii has the crown and nape paler, with less distinct mottlings. 



^ One specimen. Three other specimens, adults and fully grown immature birds 

 of undertermined sex, measure as follows: Wing, 248-276 (256.7); tail, 114^142 (125.3), 

 exposed culmen, 39-12 (40.2); tarsus, 22.5-24.5 (23.7); middle toe 19-22 (20.7). 



