42 NORTH AMERICAN BIRDS. 



grasses, etc., in marshes (fresh- or salt-water), often 

 upon " windrows" of sea-weed. Ecjfjs t.78 X 1-23, 

 ovate or short-ovate, varying from olive-buff to 

 olive-brown, coarsely spotted or blotched with 

 dark brown or blackish. Hab. Temperate North 

 America, north to Manitoba, south, in winter, to 



Brazil 09. S. forsteri Nutt. Forster's Tern. 



ff. Inner web of outer tail-feather entirely white, the 

 outer web duskj% in abrupt contrast. 

 h}. Tarsus more than .G5. 



Summer adult : Lower parts pale lavender-gray, 

 or gra3-i8h white ; whole top of head and nape 

 deep black ; rest of upper parts deep pearl- 

 graj^, the rump, upper tail-coverts, and greater 

 part of tail pure white; bill bright vermilion- 

 red, blackish at tip; feet (in life) rich orange- 

 vermilion. Winter adult: Similar, but fore- 

 head, crown, and anterior part of lores white, 

 mixed with black on crown ; entire lower 

 parts pure white; bill and feet less intensely 

 red. Young : Orbital region, occiput, and 

 nape, dull black ; crown mixed blackish and 

 grayish white ; forehead, lores, entire lower 

 parts, upper tail-coverts, inner webs of rectri- 

 ces, and tips of secondaries, white; rest of 

 upper parts pale pearl-gray, the scapulars, 

 interscapulars, and tertials, tipped with pale 

 buflf, and marked with a subterminal cres- 

 centic spot, or lunule, of dusky brown ; an- 

 terior lesser wing-coverts dusky, forming a 

 distinct bar across wing; bill brownish dusky, 

 the base of mandible paler and more reddish ; 

 feet pale reddish. Downy young : Above pale 

 fulvous or grayish buff (the precise shade 

 verj' variable) coarsely and irregularly mar- 

 bled with duskj-, except on forehead ; lower 

 parts white, more or less tinged with buff or 

 pale fulvous on sides and flanks, the throat 

 and cheeks distinctly dusky, or grayish. 

 Length 13.00-16.00, wing 9.75-11.75, tail 5.00- 

 7.00 (forked for 3.50, more or less), culmen 

 1.25-1.50, depth of bill at base about .33, tar- 

 sus .6G-.85. iW'sJ usually a depression in 

 sand or gravel near sea-shore. Eggs 2-A, 1.57 

 X 1.17, averaging a little paler in ground- 



