250 LARIN^E. RISSA. 



above and behind with a sloping, convex, thin-edged plate, 

 the sides beyond the nostrils erect and flattened, the edges 

 thin, direct, the tip narrow, rather acute, very slightly pro- 

 longed ; lower mandible narrower, compressed, with the in- 

 tercrural space long and narrow, the lower outline of the 

 crura slightly concave, forming a slight prominence at the 

 commissure, the dorsal line distinctly concave and scarcely 

 ascending, the edges thin and inflected, the tip compressed 

 and rather acute ; the gape-line commencing beneath the 

 eyes. Tongue and digestive organs as in the Gulls and 

 Mews. Legs very short ; tibia bare to a moderate extent ; 

 tarsus very short, considerably compressed, with anterior 

 decurved scutella ; hind toe extremely diminutive, with a 

 minute claw, which is obsolete in old individuals ; anterior 

 toes of moderate length, the shortest as long as the tarsus ; 

 webs entire, slightly emarginate ; claws rather small, com- 

 pressed, moderately arched, rather acute. Plumage full, 

 close, soft ; wings very long, rather narrow, pointed ; tail 

 of moderate length, even, of twelve feathers. 



Only one species is known. The genus is intermediate 

 between Larus and Cetosparactes. As in the latter, the 

 young are spotted with black, but only on the back and 

 wings. 



308. RlSSA TRIDACTYLA. KlTTIWAKE. 



Bill about an inch and a half in length, five-twelfths high 

 at the knob ; tarsus an inch and a quarter long. In winter, 

 the bill pale greenish-yellow; feet black; back and wings 

 light bluish-grey ; tips of five outer primaries and outer web 

 of first black ; the rest of the plumage pure white, except the 

 hind part of the neck and the occiput, which are pale bluish- 

 grey. In summer, the head and neck pure white, the other 

 parts as in winter. Young with the bill black, the feet 

 greenish-grey, forehead and lower parts white, a narrow black 

 crescent before the eyes, a dark grey patch over the ears, the 

 occiput tinged with grey, a dusky patch on the nape ; the 

 back deep greyish-blue ; the feathers margining the wing and 

 those along the humerus black; scapulars and secondaries 

 with a black patch ; tail white, with a broad black band, not 

 including the outer web of the outer feather. 



Male, 17, 36, 12, 1|, l, 1^, T V Female, 16, 35. 



The Kittiwakes arrive along our coasts in the end of April, 



