The nostrils are double, and situated immediately anterior to the eyes. The
anterior openings furnish small opercula, which exactly cover the posterior ones.
The branchiostegous membranes are united to each other by a plicated skin continuous
with the integuments of the abdomen, but separated from them by a transverse
shallow sulcus, and further distinguished by the absence of scales. There are
three broad flat rays in each membrane.
The mouth is retractile, and placed under the snout, but when protruded extends a
little beyond it. When the lips are closed, the orifice of the mouth has a horse-shoe
shape, but when the jaws are extended it is nearly quadrangular—it admits the little
finger. The lips are attached to the intermaxillary and lower jaw-bones, and are
rough with large papillae, particularly the lower one, which expands into two pendulous
flaps. There are no cirrhi.
The palate is lined by a thick gelatinous membrane of a light-red colour, which
rises anteriorly into two uvula-like eminences, forming the commencement of a
sulcus leading towards the pharynx. The sulcus is obliterated posteriorly by a large
pulpy cushion, against which the branchial arches may be pressed. This cushion
covers, or lines, a number of small bones and cartilages, which connect the superior
extremities of the branchial arches with each other ; united to it posteriorly, there is a
cordiform substance of firm texture and white colour, which lines an irregular
cribriform osseous plate, that projects from the basilary process of the occipital bone.
Certain processes of the inferior pharyngeal bones, when pressed against the
callous cordiform substance just mentioned, may serve to comminute the tender
insects on which this fish preys.
There are no teeth, but the processes of the inferior pharyngeal bones resemble
teeth in their form and office. These, to the number of thirty-six, project from the
bone on each side, in a pectinated manner, are compressed laterally, somewhat club-
shaped, a little worn on their summits, and gradually diminish in size, as they
recede from the maesial line. The pharyngeal bones themselves, which give origin
to these processes, are very strong, bear a resemblance in shape to the hoof of a
horse, are lined with the same membrane as the inner surfaces of the branchial
arches, and surround about two-thirds of the pharynx. The processes of these
bones are the only parts about the pharynx not thickly covered with membrane;
their hodies are continuous with, and have the same structure as, the rest of the
bone ; but two or three of the largest have narrow crowns, approaching to enamel
in texture. There is no superior pharyngeal bone, unless the very irregular process
of the occipital bone may be so denominated.
The branchial arches are furnished with a double row of thin, and rather rigid,
crests, having scolloped margins. These, when pressed against the soft cushion in
the roof of the mouth, must suffice to retain the food, until it undergoes that degree
of mastication which the apparatus in the pharynx is capable of giving.
The oesophagus is short and muscular* and its lining has a glandular appearance.
The intestinal canal, from pharynx to anus, makes four convolutions and a half, and
bears a proportion to the length of the fish, excluding the caudal fin, of 50 to
18, or 2.8 to 1. The proportions, howevetf, vary somewhat in different individuals.
The upper part of the canal, answering to the stomach, has a greater diameter ;
at the first turn it suddenly undergoes a small contraction, by which a minute sac is
formed on one side of the canal only. From this contraction to the anus, the diameter
of the intestinal canal, and the strength of its coat, diminishes gradually. Its inner
membrane is disposed throughout in minute and delicate rugae, which have a longitudinal
direction, but are indented and waved into each other in a very beautiful
manner. There are no caeca.
The lobes of the liver are numerous, and so intermixed with the folds of the
gut, that it is difficult to separate them entire. It has a pale colour. The gallbladder
lies betwixt the intestines and air-bladder. Its duct opens into the upper
part of the stomach, immediately behind the septum of the thorax. The bile is
pale.
The spleen is large, and lies in a semicircular form round the upper part of the
exterior convolution of the intestine.
The air-bladder extends the whole length of the abdomen, and consists of two
portions, united by a very short tube. The upper portion is shorter, and is furnished
with a remarkably thick shining white capsule, which adheres strongly at its upper
end to the spine and septum; a very slight degree of force suffices to thrust the
bladder out of the capsule. The true coats of both portions are firm, and less
readily torn than the above-mentioned capsule, but are much thinner. A small tube
for discharging the air proceeds from the upper end of the lower division of the
bladder.
The kidneys extend the whole length of the abdomen, and are connected with each
other, immediately below the diaphragm, by a transverse lobe. The urinary bladder
is a long tube, whose width scarcely exceeds the joint diameters of the ureters.
The lining of the abdomen is white. The intestines are attached on every side to
the parietes of the abdomen, by numerous processes of the peritonaeum.
The intestines are infested by small worms, which fix themselves to their inner
coats by a kind of proboscis.
Fins?~The pectoral fins are elliptical, and are four times and a half shorter than
the body of the fish, estimated from the setting on of the head to the base of the
caudal fin. The dorsal fin is rhomboidal ; its first ray is short, the next about two
inchesrfong, the posterior ones gradually become a little shorter; the last one is
nearly bipartite ; their numbers vary from twelve to fourteen. The ventrals are
situated opposite to the dorsal, are rather small, and have an obtuse unequal oboVate