38 NORTH AMERICAN BIRDS. 



Upper parts rusty yellow, spotted with black ; lower parts whitish gray. 

 Length 13.00-14.00, wing 10.10-11.15, tail 4.50-5.00 (forked for about .60- 

 1.00), culmen 1.00, tarsus 1.25, middle toe, with claw, about 1.25. Eggs 2-5, 

 1.78 X 1-26, ovate, or short-ovate, deep olive (varying in intensity, however), 

 rather indistinctly spotted or blotched with brown. Hob. Arctic regions; 

 in North America south, in winter, to New York, the Great Lakes, and 

 Great Salt Lake (casually to Bermudas and Peru). 



62. X. sabinii (SAB.). Sabine's Gull. 



a j . Culmen nearly as long as tarsus ; tail forked for at least one and a half times 

 the length of the tarsus ; wing about 16.00 ; legs and feet red. (Subgenus 

 Creagrus BONAP.). Summer adult : Head and upper part of neck sooty slate, 

 with a whitish patch at base of bill; mantle pearl-gray, the' wing-coverts 

 and outer webs of scapulars whitish ; quills black, the shorter ones tipped 

 with white ; rest of plumage white ; bill black, with yellowish tip ; legs and 

 feet bright red. Young: Plumage generally, including head and neck, 

 white ; hind-neck, back, and scapulars, ashy brown, the tips of the feathers 

 margined with white ; tail-feathers (except outermost) with a black subter- 

 minal spot ; a dusky space immediately in front of eye, and another on ear- 

 coverts. Length about 23.00, wing 16.00, tail 8.00 (forked for about 3.30), 

 culmen 1.85, tarsus 1.90, middle toe, with claw, 2.00. Hob. Pacific coast of 

 South America; Monterey, California? 



. X. furcata (NEB.\ Swallow-tailed Gull. 



GENUS GELOCHELIDON BREHM. (Page 24, pi. IX., fig. 4.) 



Species. 



Summer adult : Top of head and hind-neck deep black ; upper parts pale pearl- 

 gray, rest of plumage pure white ; bill deep black, feet blackish. Winter adult: 

 Similar, but head and neck white, the hind-neck tinged with grayish, the ear- 

 coverts and spot in front of eye darker grayish. Young : Similar to winter adult, 

 but upper parts washed with buff or clay-color, the top of head, hind-neck, back, 

 and scapulars sometimes streaked with dusky. Downy young : Above light gray- 

 ish buff, with several large and tolerably well defined dusky spots on hinder half 

 of head, a distinct dusky stripe down each side of hind-neck and upper back, the 

 wings, rump, and flanks with rather distinct large spots of dusky; lower parts 

 white, tinged with grayish on sides of throat ; bill brownish, inclining to orange (in 

 life) on lower mandible ; feet dull brownish orange (in life). Length 13.00-15.25, 

 wing 11.75-12.25, tail 5.50 (forked for 1.50-1.75), culmen 1.40, depth of bill at base 

 .45. Nest along sea-beach, in sand or shingle. Eggs 1.84 X 1-33, ovate, light buffy, 

 varying to pale olive-buffy, distinctly spotted and blotched with deep brown and 

 lavender-grayish. Hab. Nearly cosmopolitan ; in America, Atlantic side, from 

 Brazil north to Long Island, casually to Massachusetts; very rare inland; both 

 coasts of southern Mexico and Central America in winter. 



63. G. nilotica (HASSELQ.). Gull-billed Tern. 



