Heliases Crusma, _Cuv. et Val._ Hist. des Poiss. tom. ix. p. 377.
FORM.—Oval, very much compressed. Back considerably elevated,
particularly at the nape, whence the profile descends very
obliquely, and, with the exception of a slight concavity before the
eyes, in nearly a straight line. Greatest depth at the commencement
of the dorsal, equalling nearly half the entire length, caudal
excluded. Head contained four and a half times in the same. Snout
short: mouth small, a little protractile: lower jaw rather the
longest. A narrow band of velutine teeth in each jaw, with the outer
row in fine card; these last longest and strongest in front. Eyes
large; their diameter nearly one-third the length of the head.
Suborbitals forming a narrow curved band beneath the eyes, and
covered by a row of scales. Nostrils with only a single, small,
round aperture. Preopercle with the ascending margin vertical, not
quite rectilineal, inclining slightly inwards towards the angle,
which is rounded. Opercle, taken together with the subopercle, very
regularly curved, the margin describing nearly a semicircle, with
one flat point to terminate the osseous portion; its height double
its length.
The whole of this fish, including every part of the head, except the
lips and maxillary, is covered with scales, which extend on to the
vertical fins as in _Glyphisodon_: those on the fins and upper part
of the head and snout are very small, but those on the gill-covers
and body very large: about twenty-six or twenty-seven in a
longitudinal line from the gill to the base of the caudal, and
fourteen or fifteen in a vertical line: one taken from about the
middle of the side is oblong, the breadth exceeding the length, with
the anterior margin rounded, and the free portion finely dotted and
very minutely ciliated, the concealed portion cut square, with a fan
of eight or ten striæ not meeting at the centre, and terminating at
the basal margin in as many crenations. The lateral line commences
at one-fourth of the depth, but, from the fall of the dorsal line
posteriorly, the distance between these two lines diminishes as the
former advances: the lateral line terminates beneath the soft
portion of the dorsal fin altogether.
Fins almost exactly similar to those of the _Glyphisodon saxatilis_
and _Heliases insolatus_, as described and figured in the “Histoire
des Poissons.” The fourth and fifth spines in the dorsal longest,
equalling one-fourth of the depth; of the soft rays the third,
fourth, and fifth are longest. First anal spine only one-third the
length of the second, which is itself rather shorter than the soft
rays; and these last appear longer than in the _H. insolatus_.
Caudal more forked than crescent-shaped, the depth of the fork
equalling nearly half the length of the fin, which is itself
one-fourth the entire length of the fish. Axillary scales of the
pectorals and ventrals as in _H. insolatus_.
B. 6; D. 13/12; A. 2/12; C. 15, & 4 short; P. 21; V. 1/5.
Length 8 inches.
COLOUR.—“Above lead-colour, beneath paler.”—D. In spirits, it appears
of a deep brownish olive on the back and upper part of the sides,
passing into dull golden yellow on the lower part of the sides and
abdomen, where, however, the scales are still faintly edged with the
former colour. Fins dark.
Habitat, Valparaiso, Chile.
This species, as M. Valenciennes observes, is so extremely similar to
the _H. insolatus_, that at first sight, it would hardly be
distinguished from it. The only differences appear to consist in the
form of the caudal, which is forked, not crescent-shaped as in the
species just mentioned, and in the greater length of the soft rays of
the anal. In the figure of _H. insolatus_ in the “Histoire des
Poissons,” these rays are represented of the same length as the second
spine, whereas in the present species they rather exceed it, giving a
greater depth to the entire fin. The teeth also would seem to be more
developed in the _H. Crusma_, especially those in front, which are
longer than the others. According to Valenciennes, the outer row hardly
exceeds the inner ones in the _H. insolatus_. The geographical position
of the two species is however widely different. The _H. insolatus_ is a
native of the Caribbean Seas; whereas the _H. Crusma_ has only been
obtained on the coast of Chile and off the island of Juan Fernandez. M.
Gay first obtained it at Valparaiso, where also Mr. Darwin’s specimen
was procured; in whose notes it is stated, that it gets to a much larger
size than the one here described.