210 BLACK SKIMMER.
mandible 4£; depth of bill at the base 1; -wing from flexure 15§ tail
to the feffk 3i ; to end of longest feather 51 ; tarsus 1 | ; hind toe and
claw A ; middle too ¡§ ; its claw A- Weight 13 oz.
The female, which is smaller, is similar to the male, but with, the
tail-feathers white, excepting a longitudinal band including the shaft.
Length to end of tail 16f, to end of wing» 20è, to end of claws 16i,
tp carpus 8 ; extent of wings 44£. Weight 10 oz.
After the first autumnal moult, there is. on the hind part of the noe.k
a broad band of white mottled with greyish-black ; the lower parts
pure whites the upper of a duller black ; the bill and feet less richly
coloured.
Length to end of tail 161 inches, to end of wings 20, to end of claws
1 1 t o carpus Gjf ; extent of wings 42.
In some individuals at this period, the mandibles aré of equal
length.
The palate is flat, with two longitudinal series of papilla? directed
backwards. The upper mandible! » extremely contracted., having inter
nally only a very narrow groove, into which is received the single thin
edge of the lower mandible. The posterior aperture of t i e nares is 1 A
inch long,, with a transverse line of papilla; a t the. middle on each side,
and another behind. The tongue is sagittiform, (¡4 twelfths long, with
two conical papillae at the base, soft, fleshy, flat, above, horny beneath.
Aperture of the glottis twelfths long, with numerous small papilla:
behind. Lobes of ''the live¿ equal, 1£ inch long. The heart of ¿modérate
size¿ 1A long, 10 twelfths broad.
Thé (esophagus, 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 iff ^greatest
diameter is. ÍA- Its external transverse fibres are very distinct, as
are the internal longitudinal. The profentriculus, b, is 9 twelfths,
long, its glandule,» extremely small' and numerous, roundish, scarcely
a quarter of a twelfth in length. The stomach, is rather small,
oblong, 1 inch 4 twelfths longs 11 twelfths broad, miiscular, with the
lateral musclés moderate. The cuticular lining of the stomach is 'disposed
in nine broad longitudinal ruga- of a light red colour, as in the
smaller Gulls and 'Penis. Its lateral muscles aie about 4 twelfths thick,
BLACK SKIMMER. 211
the tendons, e, 6 twelfths ist d®meter. The intestine is 2 feet 4 inches
long, its average diameter 2$ twelfths. The rectum is 2 inches long.
One of the cocca is 4, the rtthbr 3 twelfths, their diameter l i twelfths.
In another individual, the intestine is, 22* inches long ; the cceca 5
twelfths long, 1 twelfth in diameter; the rectum If inch long; the
cloaca 9 twelfths in diameter;
The trachea is 5 | inches long, round, but not ossified, its diameter
a t the top 5 twelfths, contracting gradually to twelfths. The lateral
or contractor 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 Terns and smaller Gulls, to which it is also allied by many of its
habits.