BIRDS OF NORTH AND MIDDLE AMERIOA. 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 tip. (Pacific coast of Mexico and Southern California.) 
Sternula antillarum browni (p. 525) 
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 (extralimital).¢ 
aa. Under parts gray; tail deep gray, like back, etc. (Coast of Peru and Northern 
Chile Ne oc aeons poetics cu cirieild hihederer Sternula lorata (extralimital).> 
STERNULA ANTILLARUM ANTILLARUM (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 gray, slightly deeper gray 
on back, scapulars, and wings; two outer primaries dusky gray or 
blackish slate color, their inner webs broadly edged with white, the 
remaining primaries pallid neutral gray (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). 
Adulis 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- 
@ Sterna superciliaris Vieillot, Nouv. Dict. d’Hist. Nat., xxxii, 1819, 176 (Paraguay; 
based on Hati 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, 188.—Sterna maculata Vieillot, Nouv. Dict. d’Hist. Nat., xxii, 1819, 176 
(Paraguay; based on Hati 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. 
6 Sterna lorata Philippi and Landbeck, Wiegmann’s Archiv fir 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 Pérou, iii, 1886, 445. 
