"Adult male in breeding plumage.--Forehead, crown, and nape deep black; from the gape to the nape a conspicuous white streak; upper parts slate-gray, darker on the primaries, except when these are new and frosted; shafts white; inner webs of outer pairs of primaries white on the upper and greater part of the inner webs; upper tail-coverts gray; tail-feathers gray, with white outer webs to the outside pair; chin white or very pale gray; throat gray, darkening on the lower part; breast dark slate-gray, which deepens into black on abdomen and flanks; vent and under tail-coverts white; under wing-coverts white; axillars white with a faint tinge of gray. Bill blood-red; feet vermilion, drying to orange-color; webs deeply indented, but less so than in H. leucoptera. Length, 280; culmen, 35; wing, 235 to 241; tail, 96; tarsus, 23; middle toe with claw, 29. "Indian birds, which are probably almost sedentary, are slightly smaller in size. Some of the birds resident in South Africa are of a distinctly darker hue both above and below than northern examples; Australian specimens, on the other hand, are inclined to be paler. "Adult female.--Similar to the male, or a trifle paler in general tint. "Adult in winter plumage.--Upper parts of a paler gray than in the breeding season; forehead white; crown and nape streaked and mottled with black; under parts entirely white; bill and feet reddish brown. "Young in first plumage.--Crown and nape blackish brown, mantle mottled with brown and with warm cinnamon-brown edges to inner secondaries; tail slightly mottled and edged with ash-brown; the rest like the adult in winter. By December the brown markings are considerably diminished. "Nestling.--Down at the base of bill black, forehead ruddy fawn-color; upper parts paler fawn, mottled and streaked with black; under parts white, except the throat, which is sooty black for a few days." (Saunders.) "Common about the Pasig River and Laguna de Bay. Several flocks were observed in Mindanao feeding over the paddy-fields." (Bourns and Worcester MS.) Genus STERNA Linnæus, 1758. Bill much as in Hydrochelidon but somewhat longer; toes completely webbed; tail always distinctly forked; outer rectrices usually much longer than the others. Species. a1. Crown black. b1. Larger; wing, 240 mm. or more. c1. Forehead black to base of culmen. d1. Larger; tarsus yellow or red; bill red in summer. ... hirundo (p. 89) d2. Smaller; tarsus blackish, bill black at all seasons. ... longipennis (p. 89) c2. Forehead white. d1. Lores white. ... boreotis (p. 90) d2. Lores black. e1. Wing, 265 mm.; mantle umber-brown. ... anæstheta (p. 91) e2. Wing, 300 mm.; mantle deep black. ... fuscata (p. 92) b2. Smaller; wing less than 200 mm. ... sinensis (p. 92) a2. Crown white. ... melanauchen (p. 93) 78. STERNA HIRUNDO Linnæus. COMMON TERN.