LAEID^, TEENS. GEN. 287-^ 



317 



inch. Arctic America, apparently very rare ; I liave never seen a specimen, 

 and do not l^now of any in tliis conntrj^ Rich., F. B.-A. ii, 427 ; Ndtt., 

 ii, 295; Aud., vii, 130; Lawe. in Bd., 856; Coues, I. c. 311. . rosea. 



287-8. Genus XEMA Leach. 



^'5 «> Forlc-tailed Gull. Adult: white, inchiding inner primaries, most of 

 secondaries, and greater coverts; head enveloped in a slate-colored hood, 

 succeeded by a velvety-black collar; mantle slaty-bine, extending quite to 

 the tips of the tertiaries ; whole edge of the wing, and first 5 primaries, 

 black, their extreme tips, and the outer half of their inner webs to near the 

 end, white ; bill black, tipped with yellow ; feet black ; length 13-14; wing 

 10-11; bill 1; tarsus 1^ ; tail b, forked aw inch or more. The changes of 

 plumage are correspondent with those of h. pldladelplda ; in the young the 

 tail is often simply emarginate. Arctic America, both coastwise and in the 

 interior, common, but still rare in collections; in winter, S. occasionally to 

 New York (Audubon) and Utah (Allen). Rich., F. B.-A. ii, 428 ; K"utt,, ii, 

 296 ; Aud., vii, 127, pi. 441 ; Lawr. in Bd., 857 ; Coues, I. c. 311. sabinei. 



^. /- Cl Swallow-tailed Gull. Head and nearly all the neck grayish-brown ; a 

 white spot on each side of the forehead ; mantle grayish-white ; lesser wing 

 coverts white, greater slate, white-ljordered ; bill black at the l:)ase, white at 

 the end, much bent ; eyes and feet red; e3'elids orange; claws black; tail 

 white, very much forked. Length about 2 feet. 

 "California." This bird appears to be exceedingly 

 rare ; no one in this country has seen it. The de- 

 scription is compiled from the original account. 

 Lams furcatus Neboux, Rev. Zool. 1840, 290 ; 

 Peevost and Des Murs, Yoy. Venus, pi. 10 ; 

 Oreagrus furcatus Bonap. ; Laave. in Bd., 857 ; 

 Coues, I. c. 312 fuecatum. 



Subfamily STERNIN^'E. Terns. 



Covering of bill continuous (no cere), hard and Iiorny 

 throughout ; bill paragnatJwus, relatively longer and 

 slenderer than in the gulls, very acute, the commissure 

 straight or nearly so to the very end ; nostrils generally linear. Tail never square, 

 almost invariably forked (often deeply forficate), in one group double-rounded. 

 "Wings extremely long, thin and pointed. Feet small, weak, scarcely ambulatorial. 



The terns are not distinguished from the galls by anj^ strong structural pecu- 

 liarities, but the}' invariabljr show a special contour, in the production of which the 

 longer, slenderer and acutelj' paraguathous bill is a conspicuous element. Only one 

 species has the bill in any noticeable degree like that of a gulL A few of the terns 

 are as large as middle-sized gulls, but the normal stature is much less ; and they 

 are invariablj' of a slenderer build, more trim in shape, with smoother, closer-fitting 

 plumage. The great length and sharpness of the wing relative to the bullv of the 

 body coufer a dash and buoj'ancy of flight wanting in the gulls ; in flying over 

 the water in search of food, they hold the bill pointing straight downward, 

 which makes them look curiouslv like colossal mosquitoes ; and they secure their 



Fig. 20). Eoseate Tern. 



