THE SOOTY TERH. 
255 
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 ; 
primary quills tapering but rounded, the first longest, the rest rapidly 
graduated ; 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 with 
blue, excepting the edges of the wings and the lateral tail-feathers, which 
are white, the latter with the inner web towards the end dusky. All the 
lower parts and the sides of the neck are pure white. 
Length to end of tail 16£ inches, to end of wings 15-f, to end of claws 
Hi ; extent of wings 341 ; wing from flexure 12 ; tail to the end 7#, to the 
fork 3£ ; bill along the ridge If, along the edge of lower mandible 2 & ? 
tarsus ; middle toe f|, its claw T V 
The Female is similar to the male. 
Female. The mouth is formed as in the Cayenne Tern ; its width 8£ 
twelfths. Tongue 1 inch 4 twelfths long, emarginate and papillate at the 
base, very slender, channelled above, horny beneath, tapering to a point. 
(Esophagus 61 inches long, 1 inch wide at the commencement, 9 twelfths 
along the neck, brt within the thorax dilated into an enormous sac 1 inch 
9 twelfths in width. Stomach exceedingly small, being only 10^ twelfths 
long, 7 twelfths broad ; its muscles very thin, the epithelium strong, longi- 
tudinally rugous, and of a bright red colour. The belt of the proventricu- 
lar glands only 3 twelfths in breadth. The walls of the oesophagus are 
extremely thin, so as to be membranous and transparent. Lobes of liver 1 
inch 9 twelfths, and 1 inch 2 twelfths long ; gall-bladder £ inch long, 3 
twelfths broad. Intestine 15 inches long, 3 twelfths broad, at the com- 
mencement, diminishing to 2 twelfths ; coeca 1 inch 2 twelfths long, their 
greatest width 1§ twelfths, at the base only f twelfth ; in form and pro- 
portion they are thus like those of the genus Lestris ; their distance from 
the extremity 2 inches, cloaca globular, 9 twelfths in diameter. 
Trachea 4 inches long, from 2£ twelfths to 1 i twelfths in breadth, 
roundish, the rings 95, unossified. Bronchi very wide, of 28 rings. Mus- 
cles as in the Other species. 
