BLACK SKIMMER. 
233 
liver equai, 11 inches long. The heart of moderate size, 1 T V long, 10 
twelfths broad. 
The oesophagus, of which only the lower portion, 
a, is seen in the figure, is 8 inches long, gradually 
contracts from a diameter of 1 inch to 4 twelfths, 
then enlarges until opposite the liver, where its 
greatest diameter is 1 T 4 5 . Its external transverse 
fibres are very distinct, as are the internal longitu- 
dinal. The proventriculus, b, is 9 twelfths long, 
its glandules extremely small and numerous, round- 
ish, scarcely a quarter of a twelfth in length. The 
stomach, c d e, is rather small, oblong, 1 inch 4 
twelfths long, 11 twelfths broad, muscular, with the 
lateral muscles moderate. The cuticular lining of 
the stomach is disposed in nine broad longitudinal 
rug® of a light red colour, as in the smaller Gulls 
and Terns. Its lateral muscles are about 4 twelfths 
thick, the tendons, e, 6 twelfths in diameter. The 
intestine is 2 feet 4 inches long, its average diame- 
ter twelfths. The rectum is 2 inches long. 
One of the coeca is 4, the other 3 twelfths, their 
diameter 14 twelfths. 
In another individual, the intestine is 224 inches long ; the coeca 5 
twelfths long, 1 twelfth in diameter ; the rectum 14 inches long ; the cloaca 
9 twelfths in diameter. 
The trachea is 5f inches long, round, but not ossified, its diameter at the 
top 5 twelfths, contracting gradually to 2 \ twelfths. The lateral or con- 
tractor muscles are small ; the sterno-tracheal slender ; there is a pair of 
inferior laryngeals, going to the last ring of the trachea. The number of 
rings is 90, and a large inferior ring. The bronchi are of moderate length, 
but wider, their diameter being 3§ twelfths at the upper part ; the number 
of their half-rings about 18. 
The digestive organs of this bird are precisely similar to those of the 
Tex*ns and smaller Gulls, to which it is also allied by many of its habits. 
Vol. TO— 30 
