STERNIDJE 



STERNA 



Genus II. STERNA. 



433 



Type. 

 S. hirundo. 



Sterna, Linn. Syst. Nat. 12th ed. i, p. 227 (1766) 



Bill long, pointed, and somewhat compressed, both mandibles of 

 equal length ; nostrils elongated ovals in the basal half of the bill ; 

 wings very long and pointed, first primary the longest ; tail more or 

 less forked, the outer feathers elongated, attenuated and pointed 

 sometimes to a very considerable extent ; tarsus short, less than 

 the middle toe and claws; toes fully webbed. 



CSS 



FIG. 138. Tail of Sterna vittata. x 



Saunders recognises thirty-three species of this genus, twelve of 

 which may be considered South African, while the Caspian Tern 

 makes another addition to both numbers if it is, as here, included 

 in the same genus. The Terns are of world wide distribution and 

 are found both at sea and also on inland waters ; though apparently 

 well adapted to do so, they are seldom seen swimming. 



Key of the Species. 



A. Tail very short, less than one third of the wing ; 

 of large size, wing over 14 ; nape feathers not 



narrowed and pointed S. cas}na, p. 434. 



28 VOL. TV. 



