80 THE CAYENNE TERN. 



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 fore part of the head, 

 elongated behind, rather compact on the back and wings. Wings extremely 

 long, narrow, and pointed; primary quills tapering but rounded, the first 

 longest, the rest rapidly graduated; secondary short, rather narrow, tapering, 

 rounded. Tail long, deeply forked, of twelve feathers, of which the outer 

 taper to a rounded point. 



Bill bright carmine, the tips paler. Iris dark brown. Feet black. The 

 top of the head and occiput is greenish-black; the back and wings light 

 greyish-blue; the primary quills bluish-grey on their outer webs, darker on 

 the. outer part of the inner, their inner part white, as are the ends and inner 

 webs of the secondaries; upper tail-coverts and tail greyish-white; all the 

 other parts are pure white. 



Length to end of tail 19 inches, to end of wings 20i; extent of wings 44; 

 wing from flexure 15; tail 7; bill along the back 2|, along the edge of lower 

 mandible 1||; tarsus 3^; middle toe 1, its claw ^. Weight 14^ oz. 



The width of the mouth is 1% inches; the palate flat, with 2 prominent 

 papillate ridges, the anterior part with five faint elevated lines; the posterior 

 aperture of the nares linear, 1^ inches long, margined with papillae. Tongue 

 1 inch 1 1 twelfths long, narrow, fleshy above, horny beneath, channelled, 

 and tapering to a slit horny point. (Esophagus 9 inches long, at its com- 

 mencement 1 inch 9 twelfths wide, presently after 1^ inches, then contracting 

 to 1^ inches, and within the thorax enlarging to 1^ inches. In its form and 

 structure it is exactly similar to that of the Gulls. The stomach is of mode- 

 rate size, 2 inches long, 1 inch 9 twelfths broad; its lateral muscles rather 

 thin; the epithelium thin but very dense, longitudinally rugous, and of a 

 bright red colour. The proventricular glands, which are very numerous 

 and small, form a belt only 7 twelfths in breadth. The lobes of the liver 

 are unequal, the right 2^ twelfths, the left 2i twelfths in length; the gall- 

 bladder S twelfths long, 4|- twelfths broad. The intestine measures 34 

 inches in length, 6 twelfths in width at the upper part, contracting to 3 

 twelfths. Cceca 4i twelfths long, 2 twelfths wide; their distance from the 

 extremity only 2i inches; rectum 4 twelfths wide, but enlarging into a 

 globular cloaca 10 twelfths in diameter. 



The trachea is 6i inches long, very wide at the top, where it measures 6 

 twelfths, gradually diminishing to 3 twelfths; its rings unossified, very feeble, 

 contracted before and behind, in the middle being 112 in number. Bronchi 

 large, one with 2S, the other with 30 half rings. The muscles exactly as in 

 the Gulls. 



In the oesophagus, stomach, and intestine, this bird, as well as the other 



