LARID^. — ^LXIII. 149 



dd. Head dark — if dark below, head whitish (small or 

 slender species, with a black hood in the breeding 

 season, and the white under parts then pinkish or 

 rosy-tinted.) . . . CnBCBCocEPHAiiiis, 5. 

 B5. Tail forked ; bill black, yellow-tipped. . Xbma, 6. 

 ** Bill paragnathous (mandibles even) ; tail forked (in our species) ; 

 Terns. (Steknin^.) 

 e. Toes full-webbed ; colors chiefly white, with a black cap at 

 most seasons and the quills silvery dusky, with a long 

 white sti'ipe. 

 /. Feet black ; forehead without white crescent. 



g. Not crested ; bill stout, scarcely longer than tarsus. 



GrELOCHBLIDON, 1. 



gg. Crested ; bill slender, much longer than tarsus. 



THAIiASSBTTS, 8. 



ff. Feet not black ; back pale, no crest. . . Stebna, 9. 

 ee. Toes not full-webbed ; color quite dark. 



Htdeochbudon, 10. 

 *** Bill hypognathous — ^the lower mandible much the longer, 

 compressed like a knife-blade. Skimmers. (Rhynchopin.^.) 



Rhtnchops, 11. 



/. STERCORARIUS, Brisson. J.fiGEBS. 

 = Ziestris, Authors. 



1. S. pomaforhinus, (Temm.) Lawr. Pomaeine 

 J-EGEE. Chiefly blackish, colors varying with age; 

 middle tail feathers broad to the tip, projecting about 

 four inches; L. 20; W. 15. Northern, U. S. in winter. 



2. S. parasiticus, (Brilnn.) Gray. Paeasitic J^gee. 

 General color dark brown ; middle tail feathers acuminate, 

 projecting 4 inches; L. 18; W. 13. Northern, U. S. in 

 winter. 



3. S. buffoni, (Boie) Coues. Long Tailed Jjegee. 

 Similar, but still smaller; tail feathers filamentous, pro- 

 jecting 8 or 10 inches. Northern, U. S. in winter. 



