THE CAYENNE TERN. 
239 
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, taper- 
ing, 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 204 ; extent of wings 44 ; 
wing from flexure 15 ; tail 7 ; bill along the back 2f, along the edge of 
lower mandible lf| ; tarsus Sfy ; middle toe 1, its claw 4. Weight 144 oz. 
The width of the mouth is 14 inches ; the palate flat, with two prominent 
papillate ridges, the anterior part with five faint elevated lines ; the posterior 
aperture of the nares linear, 14 inches long, margined with papillae. Tongue 
1 inch 11 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 contract- 
ing to 1^ inches, and within the thorax enlarging to 14 inches. In its form 
and structure it is exactly similar to that of the Gulls. The stomach is of 
moderate 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 proven tricular glands, which are very numerous 
and small, form a belt only 7 twelfths in breadth. The lobes of the liver 
are unequal, the right 24 twelfths, the left 24 twelfths in length ; the gall- 
bladder 8 twelfths long, 44 twelfths broad. The intestine measures 34 
inches in length, 6 twelfths in width at the upper part, contracting to 3 
twelfths. Coeca 44 twelfths long, 2 twelfths wide ; their distance from the 
extremity only 24 inches ; rectum 4 twelfths wide, but enlarging into a 
globular cloaca 10 twelfths in diameter. 
The trachea is 64 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 28, 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 
