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RISSA. KITTIWAKE. 



Several authors, who have considered all the Gulls, 

 popularly so called, as forming a single genus, have placed 

 the Ivory Gull and the Kittiwake in mutual proximity, they 

 having been aware of an affinity indicated by a similarity in 

 the form of the bill, the shortness of the feet, and some of the 

 habits of these birds. Most writers, however, have merely 

 assigned them a station determined by their size, separating 

 them by our " Common Gull." Some again have formed the 

 Kittiwake into a genus by itself, of which the principal 

 character in their estimation is the extremely diminutive 

 size of the hind toe. Now, although in my opinion this 

 character is of very little importance, I think that the bird in 

 question differs from every other of its family sufficiently to 

 entitle it to generic distinction. 



Bill rather short, moderately stout, compressed, nearly 

 straight ; upper mandible with the dorsal line very slightly 

 convex at first, then arcuato-declinate, the ridge convex, 

 gradually narrowed, the lateral sinus rather short, wide, and 

 feathered, the nostrils submedial, linear-oblong, wider ante- 

 riorly, covered above and behind with a sloping, convex, thin- 

 edged plate, the branches convex, the sides beyond the 

 nostrils nearly erect, and flattened, the edges thin, direct, 

 the tip narrow, rather acute, very slightly prolonged ; lower 

 mandible narrower, compressed, with the intercrural space 

 long and narrow, the crura erect, convex, their lower outline 

 slightly concave, forming a slight prominence at the com- 

 missure, 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, nearly straight until beyond the nostrils, when it 

 becomes gently arcuato-declinate. 



VOL. V. 2 L 



