THE CASPIAN TERN 



231 



In the Auckland and Campbell Islands it builds in flat grassy 

 places, not far from the sea, and its small nest is made of grass. 



Family Sfernidae. 

 Bill straight, rather slender. Both mandibles of about equal 

 length. Tail forked or graduated. 



(Meyer.) 



Caspian Tern. 



Key to the Genera, 



1. Tail forked. 2 

 Tail graduated. 3 



2. Tail very short. Hydroprogne. 

 Tail more than half the length of wing. Sterna. 



3. Middle toe longer than the bill. Procelsterna. 

 Middle toe shorter than the bill. 4 



4. Bill long and slender. Micranons. 

 Bill stout at the base. Gygis. 



Genus Hydroprogne. 

 Tail very short, less than one-third of the wing, the outer 

 feathers the longest. Bill very stout and deep. Tarsus less than 

 middle toe and claw. 



