BIRDS OF NORTH AND MIDDLE AMERICA. 545 



Bill about as long as head, the exposed culmen longer than middle 

 toe with claw, its greatest deptli equal to more tlmn one-third the 

 distance from anterior end of nostril to tip of maxilla; culmen straight 

 for basal two-thirds i, approximately), sometimes even faintly concave 

 above nostrils, rather abruptly and strongly decurved for terminal 

 third; gonys decidedly to much shorter than mandibular rami, 

 nearly if not quite straight, prominent basally; nostril narrowly 

 elliptical, longitiulinal, separated from nearest loral feathering by a 

 space greater in extent than length of nostril; anterior outline of 

 feathering of forehead and lores forming an angle on base of culmen 

 (frontal antia), sloping thence backward and downward to rictus, 

 without trace of projection on lateral base of maxilla (latero-frontal 

 or loral antia). Wing long and pointed, the longest primary (outer- 

 most) exceeding distal secondaries by decidedly less than twice the 

 distance fiom tips of the latter to bend of wing, the primaries rather 

 broad terminally, with narrowly- rounded tips. Tail more than half 

 as long as wing, graduated and slightly forked, the lateral rectrices 

 about two-thirds as long as the longest (third or third and fourth 

 pairs, counting from middle), the middle pair shorter than the longest 

 by less than length of tarsus; rectrices not attenuated terminally, 

 though distinctly tapering, their tips narrowly rounded. Tarsus 

 much shorter than middle toe without claw; outer toe as long as 

 middle toe; webs between anterior toes shghtly excised. 



Plumage and coloration. — Plumage blended throughout, the occipi- 

 tal feathera without trace of elongation. Adults plain grayish 

 brown, grayer on pileum, the forehead sometimes white or grayish 

 white; a white streak on lower eyelid and small white spot on upper 

 eyelid. 



Range. — Tropical seas of both hemispheres. (Monotypic.) 



KEY TO THE AMERICAN FORMS OF ANGUS STOLIDUS.o 



a. General color lighter and browner; pileum lighter gray, becoming more distinctly 

 and extensively whitish anteriorly. (Tropical and subtropical portions of 

 Atlantic Ocean; breeding northward to coasts of Florida and Louisiana.) 



Anous stolidus stolidus (p. 546). 



n In addition to the forms of this species occurring in American waters, the follow- 

 ing subspecies are recognized by Mathews (Birds of Australia, ii, pt. 4, Nov. 1, 1912, 

 405-ill): 



(1) Anous stolidus unicolor. Sterna unicolor Xordmann, in Erman's Verz. u. Pfl., 

 1835, 17 (South Seas; coll. Berlin Mus.).— .-Ijious unicolor Boie, Isis, 1844, 188.— 

 Anous stolidus unicolor Mathews, Birds Australia, ii, no. 4, Nov. 1, 1912, 411 (Society 

 Islands; Paumotu, etc.). 



(2) Anous stolidus gilberti. (Mathews, Birds Australia, ii, no. 4, Nov. 1, 1912, 

 405, 411) (Australia.) 



(3) Anous stolidus pileatus. Sterna pileata Scopoli, Del. Faun, et Flor. Insubr., 

 ii, 1786, 92 (Philippines; based on Le Petit Fouquet des Philippines Sonnini, Voy. 



40017— 10— Bull. .50, pt 8 3G 



