BIRDS OF NORTH AND MIDDLE AMERICA. 521 



c. Under parts pure white; gray of upper parts slightly paler; black of pileum 

 less extended posteriorly; outer webs of not more than two outer primaries 

 dusky gray; bill rarely without blackish tip. (Atlantic and Gulf coasts and 

 Mississippi Valley of United States and southward to Venezuela.) 



Sternula antillarum antillarum (p. 521). 



cc. Under parts grayish white or very pale gray; gray of upper parts slightly 



darker; black of pileum extended posteriorly over median portion of nape; 



outer webs of usually three outer primaries, dusky; bill frequently without 



blackish tij). (Pacific coast of Mexico and Southern California.) 



Sternula antillarum browni (p. 525 i. 



bb. Larger (wing more than 180 mm.); bill without blackish tip; black loral streak 



narrower; color of back, etc., deeper gray. (Eastern South America from 



Venezuela to Argentina.) Sternula superciliaris (extraUmital).a 



aa. Under parts gray; tail deep gray, like back, etc. (Coast of Peru and Northern 

 Chile.) Sternula lorata (extralimital).^ 



STERNULA ANTILLARUM ANTU^LARUM (Lesson). 



LEAST TERN. 



Adults in summer (sexes alike). — Forehead and sides of crown 

 white; a narrow stripe on lores (from bill to eye), crown, occiput, 

 and upper portion of nape uniform deep black; rest of head and 

 entire under parts, including axillars and under wing-coverts, im- 

 maculate pure white; upper parts, including hindneck, rump, upper 

 tail-coverts, and tail plain pallid neutral gi'ay, slightly deeper gray 

 on back, scapulars, and wings; two outer primaries dusky gi'ay or 

 blackish slate color, their inner webs broadly edged with white, the 

 remaining primaries pallid neutral gi"ay (like coverts, etc.), their 

 inner webs edged with white; bill bright yellow, usually tipped with 

 black; iris dark brown; legs and feet orange-yellow (in life). 



Adults in winter. — Similar to summer adults but lores, forehead, 

 and crown grayish-white (purer white anteriorly), an occipital cres- 

 cent and a stripe extending from this to and surrounding eye, black- 

 ish; bill blackish or dusky; legs and feet dull yellow. 



Young. — Somewhat like winter adults, but humeral region with a 

 broad space of dusky grayish, scapulars and interscapulars with V- 



o Sterna superciliaris Vieillot, Nouv. Diet. d'Hist. Nat., xxxii, 1819, 176 (Paraguay; 

 based on JIati ceja blanca Azara, Apunt. Parag., iii, 1802, 377); Sclater and Salvin, 

 Proc. Zool. Soc. Lond., 1871, 571 (monogr.); Saunders, Proc. Zool. Soc. Lond., 1876, 

 662 (monogr.); Cat. Birds Brit. Mus., xxv, 1896, 124. — Sternula superciliaris Boie, 

 Isis, 1844, 183. — Sterna maculata Vieillot, Nouv. Diet. d'Hist. Nat., xxii, 1819, 176 

 (Paraguay; based on Ilati manchado Azara, Apunt. Parag., iii, 1802, 377=young). — 

 Sterna argentea Maximilian, Reis. Bras., i, 1820, 67 (Beitr. Naturg. Bras., iv, pt. ii, 

 1823, 871 (Rio Parahyba, s. e. Brazil; type now in coll. Am. Mus. N. H.). — Sternula 

 argentea Boie, Isis, 1844, 183. 



b Sterna lorata Philippi and Landbeck, Wiegmann's Ai-chiv f iir Naturg., 1863, 

 pt. i, 124; Saunders, Cat. Birds, Brit. Mus., xxv, 1896, 126. — [Sterna] loricata Gray, 

 Hand-list, iii, 1871, 121, no. 11068. — Sterna exilis (not of Tschudi) Sclater and Salvin, 

 Proc. Zool. Soc, Lond., 1867, 336, 344 (monogr.); Saunders, Proc. Zool. Soc. Lond., 

 1876, 663 (monogr.); Taczanowski, Orn. du Perou, iii, 1886, 445. 



