304 THE LAEID^. 



is slightly open, they plunge the lower mandible of their long bill 

 into it ; they then break the ligament of the shell by beating it 

 against the rock. The tenement being thus destroyed, there is 

 no obstacle to their devouring the inhabitant. 



The only remarkable species of this bird is the Black Scissors- 

 bill {Rynchops nigra), frequently called the Cut- water. It is about 

 the size of a Pigeon ; its prevailing colour is white, top of the 

 head and shoidders black, with a white band on the wings. These 

 birds are very numerous in the West Indian seas. They fly with 

 a slow motion, and, like the Gulls and other sea-birds, they occa- 

 sionally form such dense flocks that the sky is actually darkened 

 for the space of a league. 



Gulls and Allied Species. 



Gulls and their congeners include the well-known shore-birds 

 generally called Gulls, more especially the Skuas (Lestris), Gulls 

 {Larus), and Mews (Gavia). They are characterised by a light 

 body, more or less compact ; neck of moderate length ; head ovate ; 

 bill shorter than the head, straight, compressed ; convex ridge on 

 upper mandible, nasal groove long ; lower mandible with the angle 

 long and narrow ; mouth moderate ; tongue fleshy ; eyes small ; 

 legs generally short ; tibia bare ; tarsus short, compressed ; hind 

 toe small ; middle toe longest ; fore toe moderate in length and 

 slender ; connecting membrane fuU, margins only concave ; claws 

 generally small, arcuate, acute, and more or less compressed. 



These birds inhabit the sea-shore, along which they wander in 

 search of food ; the larger species preying on fish, Crustacea 

 and moUusca, and the carcasses of cetacea and other marine 

 mammalia cast up by the sea. They all pursue shoals of fish 

 in the open sea, often to great distances from land. Their 

 plumage is full, soft, close, elastic, and well blended on the back 

 and wings ; wings long, broad, and pointed ; the tail, of twelve 

 feathers, rounded and forked. 



The Sea Mews (Gavia) are connected with the Terns, yet 

 still have some characteristics of the Gulls. However, they 

 are of smaller size than the latter, have more slender forms, 

 and their feet and bills are comparatively feebler. "We shall 



