46 NORTH AMERICAN BIRDS. 



1.40-1.60, depth of bill at base .35-.40, tarsus .85. Sab. Tropi- 

 cal sea-coasts in general ; accidental on Florida coast. 



76. S. ansethetus Scop. Bridled Tern. 

 a 2 . Wing less than 7.00. Tail about half as long as wing, forked for about half its 

 length. (Subgenus Sternula Boie.) 

 Summer adult : Above uniform pale pearl-gray ; lower parts, with forehead 

 and stripe on each side of crown, back and above eyes, pure white; 

 stripe from bill to eye, with crown, occiput, and nape, uniform deep 

 black ; bill bright yellow, usually with blackish tip ; feet bright orange- 

 yellow (in life). Winter adult: Similar to sutnmer plumage, but lores, 

 forehead, and crown grayish white (pure white anteriorly) ; bill dull 

 yellowish, or dusky ; feet pale yellow. Young : Somewhat like winter 

 adult, but lesser wing-coverts chiefly dusky slate (forming distinct 

 patch), scapulars and interscapulars with submarginal V- or U-shaped 

 marks of dusky, and quills darker. Downy young: Above grayish white, 

 varying to delicate buff-yellow, sometimes immaculate, but usually finely 

 mottled with dusky grayish, the head distinctly marked with irregular 

 dots of blackish ; lower parts wholly immaculate white. Length 8.50- 

 9.75, wing 6.60, tail 3.50 (forked for about 1.75), culmen 1.20, tarsus .60. 

 Nest a depression in shingly beach. Eggs 2-4, 1.28 X 0.91, white, buffy 

 white, or buff, spotted with brown and purplish gray. Sab. United 

 States (rather southerly) south, in winter, through Middle America 

 (both coasts) to northern coasts of South America. 



74. S. antillarum Less. Least Tern. 



Genus HYDROCHELIDON Boie. (Page 24, pi. XII., fig. 2.) 



Species. 



a 1 . Wing less than 9.00. Head wholly dusky or black in summer adult. 

 b 1 . Tail and upper coverts deep gray or plumbeous. 



Summer adult : Head, neck, and lower parts uniform black or plumbeous, 

 the lower tail-coverts, however, white; upper parts uniform plum- 

 beous. Winter adult : Head, neck, and lower parts white, the orbits 

 and ear-coverts dusky ; above as in summer. Young : Similar to 

 winter adult, but feathers of back, etc., tipped with dull brownish, 

 anterior lesser wing-coverts dusky, and sides washed with plumbe- 

 ous. Downy youn'g : Above umber-brown, with a few coarse, irreg- 

 ular mottlings of black ; forehead, crown, throat, and chest plain 

 sooty brown ; side of head, including lores, dull whitish ; belly 

 white centrally, sooty gray exteriorly. 

 c\ Summer adult with lower parts (sometimes head also) plumbeous, little 

 if any darker than upper surface. Sab. Europe, and parts of Asia 

 and Africa. H. nigra (Linn.). Black Tern. 1 



1 Sterna nigra Linn., S. N. ed. 10, i. 1758, 137. Hydrochelidon nigra Boie, Isis, 1822, 563. 



