COMPENDIUM OF GENEEIC DISTINCTIONS. 



781 



Genus. Stercorarius. — Keel of bill covered with mem- 

 branous or bony cere, tip wattled and strong ; nostrils narrow, 

 in fore part of cere. Wings, first quill longest ; two central 

 feathers of tail sometimes lengthened. Hind toe very small. 

 Habitat — High latitudes of both hemispheres. 



Genus. Larus. — Bill not longer than head, nostrils at 

 side and near middle, longitudinal. Wings, first quill 

 longest. Tail even. Habitat — Most parts of world. 



Genus. RiSSA. — Bill longer than head. Hind toe rudi- 

 mental. Habitat — Northern parts of world. 



Sid)-famihj. Ehyncopinse. — Upper mandible much shorter 

 than lower, and grooved to receive edge of lower, much 

 compressed throughout. Wings, long, sharp, curved at tip. 

 Tail forked. Front toes partly united by indented web. 



Genus. Rhtncops. — Bill broad at base, then suddenly 

 compressed ; lower mandible truncated. Wings, first quill 

 longest. Hind toe elevated, touching ground with tip, 

 claws long and curved. Habitat— Tropical parts of world. 



Sult-fumil)/. Sterninse. — Bill long, slender, straight, and 

 sharp ; nostrils narrow at side of base. Wings long and 

 pointed. Tail forked. Toes webbed. 



Genus. Sterna. — Nostrils with plumes reaching the 

 opening. Wings, first quill longest. Front toes united by 

 indented web ; hind toe very short. Habitat — Most parts 

 of world. 



Genus. Anous. — Bill longer than head, gradually curved 

 above to tip. Tail with sides rounded or forked. Wings, 

 first quill longest. Toes long and fully webbed, outer 

 larger than inner. Hind toe long and slender. Habitat — 

 Tropical seas. 



Famihi. PELECAN'ID.ffi.— Bill long, broad at base, 

 straight, and compressed. Nostrils very narrow. Sometimes 

 a pouch from base of lower mandible. Wings long, first 

 quill longest. Tarsi short and strong. All toes united by 

 membrane. Face and throat partially feathered. 



Sub-family. Phaetoninae- — Bill long as head, sharp, 



gently curved above. Two middle feathers of tail very long 

 and narrow. 



Genus. Phaeton. — Edges of bill notched, nostrils partly 

 closed by membrane. Wings, first quill longest. Claws 

 small. Habitat. — Tropical seas. 



Sub-famili/. Plotinae— -Bill with edges finely notched, 

 nostrils covered by a shield. Tail long and widening towards 

 end. Front toes broadly webbed. Hind toe united to inner 

 by web. 



Genus. Flotus. — Bill longer than head, straight, slender, 

 very sharp ; nostrils scarcely visible. Wings, second and third 

 quills longest. Outer toe long as middle. Habitat — Warmer 

 parts of Asia, Africa, and America. 



Suh-family. Pelecaniaae' — Bill long, flattened above, 

 compressed, hooked at tip ; nostrils in grooves, hardly 

 visible. Tail short. All toes united by web. Lower man- 

 dible and throat with membranous pouch. 



Genus. Sula. — Bill sti-aight, slightly curved towards tip, 

 grooved, and edges unequally notched. Wings, first and 

 second quills longest. Tail graduated. Tarsi with keel 

 behind. Claw of middle toe notched, that of hind toe i-udi- 

 mental. Below lower mandible and on breast, a naked 

 expansile space. Habitat — Many parts of world. 



Genus. Graculus. — Bill straight, slender. Wings, second 

 and third quills longest. Tail rounded. Habitat — Most 

 parts of both hemispheres. 



Genus. Pelecanus. — Bill very long, rounded above at 

 base, flat towards tip, which is strongly hooked, lower man- 

 dible broader at base than \ipper, narrowing to tip. Wings, 

 second quill longest, secondaries nearly as long as quills. 

 Tail short and rounded. Lower mandible with large exten- 

 sile pouch. Habitat — -Many parts of world. 



Genus. Atagen. — Bill longer than head, flattened and 

 concave above, then suddenly hooked and sharp, sides com- 

 pressed and gi-ooved. Wings very long and narrow, first 

 and second quills longest. Tail very long and deeply forked. 

 Tarsi very short, half feathered. Throat naked, capable of 

 being dilated into a pouch as far as breast. Habitat — 

 Trojiios. 



