148 BIRDS. 



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, 

 ZiCiridce^ below descrijjed, and Procellai'idce^ the Petrels, 

 which we here omit, all our numerous representatives 

 being strictly maritime. 



FAMILY LXIIL — LARIDJ5. 



( The Gulls.) 



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. Gen.era 



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



ninety; abounding about all large bodies of water. Of 



the genera admitted below, Pagophlla^ Hissa^ and 



(Jhroecocephalus may properly be considered as sections 



of Larus^ while Gelochelidon and Thalasseus are perhaps 



sub -genera under Sterna. 



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



f Bill with a sort of cere ; middle tail feathers exscrted ; Jjcgers. 

 (Lestridin^.) .... Stercokarius, 1. 



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

 mantle. Gulls. (Larin/E.) 



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



aa. Hind toe perfect, provided with a claw. 



h. Tail even. 



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



Gavia, 4. 



cc. 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.) . Larus, 2. 



