176 



DIVISION II. 



Rostrum rectum, apice adunco. 

 Beak straight^ its tip bent down. 



XEMA, 



XEME. 



Generic Character, 



Rostrum breve, subgracile, 

 rectum, lateratim compres- 

 sum, apice adunco: man- 

 dibula inferiore subtus 

 subangulata. 



Nares gracillimi, lineares. 



Pedes graciles; t'lhice parte 

 inferiore nuda;. 



Cauda forficata. 



Beah short, slender, straight, 

 laterally compressed, its 

 tip bent down ; the lower 

 mandible somewhat angu- 

 lated beneath. 



Nostrils very slender, linear. 



Legs slender; tibice naked 

 on the lower part. 



Tail forked. 



XEMA. Leach. 

 LARUS. Sabine, Temm. 



The forked tail at once distinguishes this genus 

 from the rest of the Gulls, from which it also diflPers 

 in its more slender and Tern-like appearance ; its 

 beak and legs are much weaker than those of the 

 Gulls, and the former is much more feathered at 

 its base than that of the Gulls ; and the tibiae have 

 their lower parts, just above the knee, naked. 



