SOOTY TERN. 269 



sides convex, the edges sharp and inflected, the tip acute. Nasal groove 

 extended to beyond half the length of the bill, slightly inflected towards 

 the edge ; nostrils basal, linear, direct, pervious. Lower mandible with 

 the angle very narrow, acute, extending to a little beyond the middle, 

 the dorsal line straight, the sides convex, the sharp edges inflected, the 

 tip very acute. 



Head of moderate size, oblong, compressed ; neck of moderate length; 

 body slender ; feet very small, wings and tail very long. Tibia bare for 

 a short space ; tarsus very short, slender, roundish, covered anteriorly 

 with small scutella, laterally and behind with reticulated rather indistinct 

 scales ; toes small, slender, the first very small, the third longest, the 

 fourth nearly as long, the second much shorter, all scutellate above, the 

 anterior united by reticulated webs, having an incurved margin ; claws 

 curved, compressed, acute, that of hind toe smallest, of middle toe by 

 much the largest, and having the inner edge thin and dilated. 



Plumage soft, close, blended, very short on the head ; the feathers in 

 general broad and rounded. Wings very long, narrow and pointed ; pri- 

 mary quills tapering but rounded, the first longest, the rest rapidly gra- 

 duated ; secondary short, broad, rather acute, the inner more tapering. 

 Tail long, very deeply forked, of twelve feathers, of which the outer are 

 tapering, the middle rounded and short. 



Bill and feet black. Iris chestnut. Forehead white ; lores, upper 

 part of the head, the hind neck and all the upper parts, deep black 

 glossed M'ith blue, excepting the edges of the wings and the lateral tail- 

 feathers, which are white, the latter with tlie inner web towards the end 

 dusky. All the lower parts and the sides of the neck are pure white. 



Length to end of tail 16j inches, to end of wings 15f , to end of claws 

 11^ ; extent of wings 34| ; wing from flexure 12 ; tail to the end 7|, to 

 the fork 3| ; bill along the ridge 1 1, along the edge of lower mandible 2^%; 

 tarsus -\^ ; middle toe ||, its claw j\. 



The Female is similar to the Male. 



