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Genus II.— STERNA, Linn. TERN. 



Bill longer than the head, rather stout or slender, nearly straight, com- 

 pressed, very acute; upper mandible with the dorsal line slightly arched, the 

 ridge rather broad and convex at the base, gradually narrowed toward the 

 end, sides convex, edges sharp and direct, tip acute; nasal groove short; 

 lower mandible with the angle very narrow, acute, extending to the middle, 

 the dorsal line straight, the sides slightly convex, nearly erect, the sharp 

 edges inflected, the tips very acute. Nostrils basal, lateral, linear, direct. 

 Head rather large, oblong; neck of moderate length and thick; body slender. 

 Feet short, moderately stout; tibia bare for a considerable space; tarsus short, 

 roundish, covered all round with small scales; first toe very small, third 

 longest, fourth a little shorter; anterior toes connected by emarginate webs. 

 Claws slightly curved, compressed, acute. Plumage soft, close, blended, 

 rather compact on the back and wings. Wings extremely long, narrow, and 

 pointed, the first quill longest, the rest rapidly graduated. Tail long, gene- 

 rally forked, of twelve feathers. Tongue very slender, tapering, with the 

 point slit; oesophagus extremely wide; proventricular belt complete; stomach 

 rather small, moderately muscular, with the epithelium dense and longitu- 

 dinally rugous; intestine of moderate length, rather narrow; coeca small. 



