GULLS AND TERNS 27 



were plentiful, every flock had adults iu nuptial plumage, showing 

 that the young are not without experienced leaders on the return 

 north. " 



GENUS XEMA. 



62. Xema sabinii (Sab.). Sabine Gull. 



Bill gull-like, tail conspicuously forkerl, the feathers rounded, not nar- 

 row and pointed at ends, ^idult.s in suininer : head and upper 

 neck dark plundjeous. bordered below by a black collar ; man- 

 tle slaty gray ; tail and middle of wing- white ; outer quills 

 Fig. 4G. black, with inner webs and tips white ; under parts white ; 

 bill black, tipped, with yellow. Adults in ivinter : head and 

 neck white, with dusky on ear coverts 

 and back of head. Yoiuiy : like winter 

 adults, but mantle brownish, feathers 

 with buffy or grayish edges ; tail with 

 a subterminal black band, white tip ' Fig. 4i. 



and base; bdl black. Length: l;]-14, wing 10.10-11.15, bill l.UU, tail 

 4.0O-.5.OO. fork .(1()-1.00 deep. 



Distribution. — Arctic regions of North America ; south in winter to 

 Peru. Not common in the United States, but recorded from many scat- 

 tered localities. 



Eygs. — Laid on the ground, or on a few grass blades and stems ; 2 to 5, 

 olive, indistinctly spotted with brown. 



GENUS GELOCHELIDON. 



63. Gelochelidon nilotica (llasse/q.). Gull-hillld Tep.n. 



Bill stout, depth at base equal to one third of its length ; tail forked. 

 Adults in smnmer : top and back of head black ; upper parts light pearl 

 gray ; lower parts white ; bill black ; feet and legs blackish. ^Idults in 

 winter : head and neck white ; ear coverts and spot in front of eye gray. 

 Youny : similar to winter adults, but u})per parts washed with buffy and 

 .sometimes streaked with duskv. Length: l.j.00-15. 25, wing 11, 75-12. lio, 

 bill 1.40, tail 5.50. forked for 1..j0-1.75. 



Distribution. — Almost cosmopolitan. In America from Brazil to Massa- 

 chusetts along the Atlantic coast, and both coasts of Mexico and Central 

 America ; rare inland. 



GENUS STERNA. 



General Characters. — Bill slender and sharp ; tail dei-jdy forked, the 

 outer feathers narrowed or sharp-pointed ; wings vej'y long and slender. 



KKV TO SPECIES. 



1 . Black feathers of crown elongated into a cre.st. 



2. Size large, wing- 14-15 maxima, p. 2S. 



2. Size smaller, wing 1 2.40-1 2..50 elegaus. p. 29. 



r. Head not crested. 



2. Size largf, feet black Caspia, p. 28. 



2'. Size small, feet red. orange, or yellow. 



8. ('h)wn and forehi^ad black in summer adults, wing over '.'. 



4. Outer web of outer tail feather white . . . foisteri, p. 29. 

 4'. Outer web of outer tail featlu*r dusky. 



5. Bill orange, witli black ti]) hirundo. p. 29. 



5'. Bill vermilion, without hhuk lip . . paradiscea, j). .'50. 

 .".' Forehead always white, wing untUi- 7 . . antillarum. )>. .">0. 



