148 BIBDS. 



trils developed; no gular pouch. Wings very long and 

 pointed. Tail well developed; altricial; powers of flight 

 remarkable; food chiefly fishes. There are two families, 

 LaridcB, below described, and ProcellaridcB, the Petrels, 

 which we here omit, all our numerous representatives 

 being strictly maritime. 



FAMILY LXIII. — LARID^, 



(The Gulla.) 

 Long -winged birds, with the nostrils not tubular; 

 bill various. Hind toe small and elevated, but less so 

 than in the Petrels. General color usually white, with 

 a darker mantle of a pearly bluish tint, and commonly 

 with some black markings. Sexes alike in color, but the 

 plumage varying much with age and season. Genera 

 about twelve (Coues), sixty (European authors) ; species 

 ninety; abounding about all large bodies of water. Of 

 the genera admitted below, JPagophila, Hissa, and 

 Chroscocephaltis may properly be considered as sections 

 of Ziarus, while Gelochelidon and Thalasseus are perhaps" 

 sub - genera under Sterna. 



* Bill hooked (epignathous) — rarely not hooked, and the tail even. 

 t Bill with a sort of cere ; middle tail feathers exserted ; Jaegers. 



(LEBTRIDIUai.) StBRCORAEIUS, 1. 



\\ Bill not cered ; general color usually white with a darker 

 mantle. Gulls. QuKRISM.) 

 a. Hind toe rudimentary, without a developed claw. RissA, 3. 

 CM. Hind toe perfect, provided with a claw. 

 5. Tail even. 

 e. Tarsus black, rough ; webs incised ; plumage white. 



Pagophila, 4. 

 ec. Tarsus not black ; lower plumage white in adult. 

 d. Head white — if dark below, head not whitish (spe- 

 cies of large size ; never rosy -tinted below ; the 

 head never with a dark hood.) Labus, S. 



