Exocœtus exsiliens, _Bl._ Ichth. pl. 397.
FORM.—Head about one-sixth of the entire length, and approaching to
the form of a parallelopiped; very much flattened on the crown and
between the eyes quite to the end of the snout, broader above than
beneath, so that the cheeks are beyond the vertical inclining inwards
at bottom. Snout short: mouth not much cleft; when shut, the jaws are
equal, and the commissure of the lips appears to extend to beneath the
anterior margin of the eye, but the maxillary, which retires
completely beneath the suborbital, does not reach so far: when the
mouth is open, the maxillary becomes vertical, and the intermaxillary
being scarcely at all protractile, the lower jaw is a little the
longest. Teeth very minute: a row, scarcely visible, along the
forepart of the intermaxillary, but not extending to the sides of the
jaw: none that can even be felt in the lower jaw, or in any other part
of the mouth. Tongue rounded, and free at the tip. A loose veil of
skin hangs down in front of the palate, from immediately behind the
teeth in the upper jaw. Eyes round, and very large; the upper part of
the orbit reaching to the line of the profile, and forming a slightly
salient ridge: their diameter very nearly one-third the length of the
head; between them and the end of the snout is two-thirds of a
diameter; the distance from one to the other across the crown is one
diameter and a quarter. The nostrils consist of one large round
orifice a little in advance of the eyes. The membrane of the opercle
forms a slightly salient angle backwards, near the upper part of the
gill-opening. Scales large, of a somewhat irregular form, approaching
to oblong, nearly twice as broad as long, the posterior margin with
three or four incisions near the middle, and a few rather indistinct
nearly parallel striæ on the surface of the basal portion; in others
these striæ converge to form a small but very regular fan; and the
scales appear to vary a good deal on different parts of the body.
[Illustration:
_Fish. Pl. 23._
_B. Waterhouse Hawkins del._
]
_N^o. 1. Tetragonopterus Abramis._ _All Nat. Size._
_2. rutilus._ „
_3. scabripinnis._ „
_4. interruptus._ „
_1a. 2a. 3a. 4a. Magnified View of Teeth._
The pectorals reach exactly to the base of the lateral caudal rays;
the first two rays are simple, and all the others branched; first ray
of all not half the length of the fin. Dorsal so situate as to leave a
space between it and the end of the fleshy part of the tail about
equal to its own length; the first ray simple, the others branched;
the last prolonged beyond those which immediately precede it so as to
form rather a point backwards. Anal similar to the dorsal, and
answering to it exactly. The ventrals are attached at a point, in this
specimen, about half an inch posterior to the middle of the entire
length, reckoning this to the end of the fleshy part of the tail; but
are not much out of the middle, if the length be reckoned to the end
of the upper lobe of the caudal: their length is contained not quite
three and a half times in the entire length, excluding caudal; and
they reach exactly to the end of the dorsal and anal: first ray very
much branched, and only one-third the length of the fin; second ray
appearing like two or even three rays at its upper extremity, from the
circumstance of the several branches of it being of unequal length;
all the other rays branched likewise. Vent a very little in advance of
the anal. Upper lobe of the caudal one-third shorter than the lower;
this last being exactly the same length as the ventrals.
D. 11; A. 12; C. 16, &c.; P. 18; V. 6.
Length 12 inches 8 lines.
COLOUR.—The colours were not noticed in the recent state; and the
specimen is in such bad condition, and so much altered by the
spirit, that they are now no longer distinguishable.
The flying-fish above described was taken by Mr. Darwin in the Pacific
Ocean, off the coast of Peru, in Lat. 18° S. It appears to be the _E.
exsiliens_ of Bloch, but as I am not aware that the species of
_Exocœtus_ have been ever rigourously worked out, and closely compared
from different parts of the globe, I have thought it expedient to annex
a description, by which it may be identified, if it prove hereafter
distinct.[34]