640 CAYENNE TERN. 



thin but very dense, longitudinally rugous, and of a bright red coloiir. 

 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 gaU-bladder 

 8 twelfths long, 4| twelfths broad. The intestine measures 34 inches 

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

 twelfths. Coeca 41 twelfths long, 2 twelfths wide ; their distance from 

 the extremity only 2{ iaches ; rectum 4 twelfths wide, but enlarging in- 

 to a globular cloaca 10 twelfths in diameter. 



The trachea is 6| inches long, very wide at the top where it mea- 

 sures 6 twelfths, gradually diminishing to 3 twelfths ; its rings unossi- 

 fied, 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 Terns, is precisely similar to the smaller Gulls, as it is also in the 

 form, structure, and muscles of the trachea. In these respects, the 

 Terns also resemble the Shear-Water. The bill of the Cayenne Tern 

 evidently indicates an af&nity to the Phaetons, and in a less degree to 

 the Gannets, as does the head, which is very large in proportion to the 

 bird. On the other hand, as regards the bill, the affinity is to the 

 larger Gulls and the Shear-Water. The feet resemble those of the 

 Gulls, but are proportionally smaller, these birds being more volatorial, 

 and the Gulls combining that character with an affinity to the Wading 

 Birds, while the Shear-Water exhibits the abbreviated feet of the purely 

 Flying birds in a still greater degree. 



