180 



RISSA. KITTIWAKE, 



Generic Character. 



Rostrum mediocre rectum, 

 lateratim compressum, 

 apice adunco; mandibula 

 inferiore subtus angulata. 



Nares lineares, rectae, in me- 

 dio rostri sitae. 



Cauda subfurcata. 



Pedes tetradactyli ; polka: 



fere obliteratus, exungui- 



culatus. 



BeaJc moderate, straight, la- 

 terally compressed, its tip 

 bent down; the lower man- 

 dible angulated beneath. 



Nostrils linear, straight, 

 placed in the middle of 

 the beak. 



Tail slightly forked. 



Legs four-toed; the Jiinder 

 toe nearly obliterated, and 

 without a claw. 



RISSA. Leach. 



LARUS. Linn., Gmel., Lath. 



GAVIA. Briss. 



The Kittiwake differs from the Xemes by reason 

 of the absence of the hinder toe, and from the Gulls 

 by the same character, added to the subfurcate tail. 

 There is but one species known, which prefers the 

 inland lakes to the sea-coasts. 



