657 



HYDROCHELIDON. MARSH-TERN. 



Some small Terns, differing from the rest chiefly in having 

 the tail less forked, and in preferring fresh water marshes to 

 the shores of the sea, have heen separated to form a generic 

 group, to which Boie and the Prince of Canino give the name 

 of Hydrochelidon. Mr. Stephens, adopting Dr. Leach's name 

 Viralva, had also proposed to form a genus of the same mate- 

 rials. Not finding that the species referred to presents such 

 differences in the bill or feet, or even in the wings or tail, as 

 could fully justify a distinction of this kind, I admit the 

 genus only with doubt, and am unable to define it with pre- 

 cision. 



Bill as long as the head, slender, nearly straight, com- 

 pressed, very acute ; feet small ; interdigital membranes 

 deeply emarginate ; wings very long, narrow, and pointed ; 

 tail of moderate length, emarginate, of twelve rounded 

 feathers. 



They frequent marshes ; feed on insects as well as small 

 fishes ; and have a very rapid and gliding flight. 



VOL. V. 



