158 ANHINGA OR SNAKE-BIRD.
of thé Cormorants. and Pélicans. The sternum in particular is almost
precisely similar to that of the Crestod Cormorant, so that without
entering very minutely into its description, no différences could tie
pointed out.
Both mandibles are concave within ; the palate.flat, with tv.o longitudinal
ridges ; the posterior aperture of the riares linear and 9 twelfths
•long:,.the anterior or external aperture entirely qUiprateè. The: lower .
mandible has a distinct oblique joint at about a third of its length,
enabling it to be?expanded to the extent of an inch and a half. The
pouch, which is small, is constructed in the samo manner as that of
the Pelicans and Cormorants ; its muscular fibres running from ths
lower edge of the mandible downwards and backwards, and a slender
muscle passing from the anterior part, of the hvoid bone to. the junction,
of the crura of the. mandible. The tongue is reduced, to a mere
oblong knob, 1|:twelfth long, and t. twelfth in height. t | | aperture
of the glottis is 3 twelfths long, with two roundish thin edged flaps behind,
destitutS of papillae. There is à small bone appended to the occipital
ridge, 4 inch in length, as in the Cormorants. ,.
The oesophagus a i, is 17 inches long, exceedingly delicate and dilatable,
with external longitudinal fibres,, the transverse fibres becoming
Stronger towards the lower parts. It> diameter when moderately dilated
is 1 | inch at the "top, 1 inch farther down, at its entrance into tliu thorax,
9 twelfths, ar.d finally l-iim-h; but it mayhe.lilatecl to a much greater
e x t e n t . Thu ¡.rotentricular gfonds. instead of/ormino a belt'it the lower part
of the ¡esophagus, are placed on the right tide in the form of a globular sac,
about an inch in diameter, eommunicátingwith the oesophagus, S, and sto-
• mach, d. For two inches, of the lower part of the oesophefus, ícorat that
part usually occupied by the proventri.:ulu.s, the transverse muscular fibres
are enlarged, and form an abrupt margin beneath.;, on the inner surface
there are four irregular series of large apertures of gastric glandules or
crypts, the proventriculus itself,o, is composed of large crypts of irregular
form, with very wide apertures,, and covered externally with,
muscular fibres. The stomach, id, is roundish, about an inch and three
quarters in diameter, with two roundish tendinous spaces, e, and fasciculi
of muscular fibres ; its inner coat thin,, soft, and smooth. If opens by
an aperture a quarter of an inch in diameter into a small s a c , / precisely
similar to that of the Pelican, which has a muscular ;coat, with a soft
even internal membra», like that of the stomach. The pylorus has a
ANHINGA OR SNAKE-BIRD. 15 9
diameter of 2 twelfths, is dosed by a semilunar valve or flap, and is surrounded
by a disk of radiating rug® three-fourths of an inch in diameter.
The intestine, g h, is 3 feet 4 inches long, its average diameter
2i twelfths, but only .1 twelfth at its junction with the rectum, which is
31 inches long, 3 twelfths in diameter. The cloaca globular, inch
in diameter- There are no cosca properly so called, but a small rownded
termmatwn of the rectim 2 twelfths in length as in the Herons.