Corvina adusta, _Spix et Agass._ Pisces Brazil. p. 126. tab. 70.
FORM.—Greatest depth beneath the commencement of the first dorsal fin,
and equalling one-fourth of the entire length. Back somewhat
carinated, and moderately arched, forming one continuous curve with
the profile, which falls with considerable obliquity. Ventral line
nearly straight, and the abdomen much flattened in front of, and
between the ventrals. Length of the head just equalling the depth of
the body. Snout obtuse, with two small lobes at bottom, one on each
side of the extremity, as in several other species of this genus.
Mouth horizontal, at the bottom of the snout; when closed, the
maxillary reaching a little beyond a vertical from the anterior
margin of the orbit. Four pores beneath the symphysis; and seven, in
two rows, round the extremity of the snout; those in the lower row
large. Jaws nearly equal; the upper one perhaps a little the
longest. Teeth forming a velutine band above and below; those above
with an outer row of somewhat longer and stronger ones. Eyes rather
small; their diameter about one-fifth the length of the head.
Nostrils consisting of two round apertures in advance of the eye,
the posterior one largest; the anterior with a raised margin.
Preopercle a little less than rectangular, with the angle at bottom
somewhat rounded: the ascending margin rectilineal, sloping rather
in advance of a vertical, and distinctly toothed, the teeth becoming
smaller upwards: at the angle are two stronger teeth or spines, the
uppermost directed backwards and a little downwards, the lowermost
downwards and a little backwards; between these two teeth there is
an interval; the basal margin of the preopercle is quite smooth.
Opercle terminating in two flat inconspicuous points.
Snout, cheeks, and gill-covers, covered with scales of very unequal
sizes: those serving as a boundary between the cheek and the
preopercle, also a row above each orbit, a few at the upper angle of
the opercle, some on the suprascapular lamina, and a row extending
thence upwards and forwards to the occiput, much smaller than the
others. Scales on the body of moderate size, arranged in oblique
rows; about fifty-five in a longitudinal line, and nineteen or
twenty in a vertical. One taken from above the lateral line, and
nearly in the middle of the length, is oblong, approaching to
circular, its surface marked with a number of concentric, much
crowded, curved lines, somewhat undulating behind, with a fan of
about twelve deeper striæ converging to a point considerably in
advance of the centre of the scale; the free portion is also marked
with several well-marked nearly parallel lines which terminate in
denticles at the anterior margin. Those on the lateral line have the
mucous tubes somewhat ramified, and are accompanied throughout its
course by some minuter scales, similar to those on the head above
pointed out. The lateral line is at one-third of the depth, till it
arrives beneath the middle of the soft dorsal, where it falls to
one-half.
First dorsal of a triangular form, separated from the soft portion by
a deep notch; the first spine very small and inconspicuous; the
second somewhat shorter than the third; fourth longest, nearly
equalling half the depth; all the spines in this fin rather slender.
The second dorsal commences with a spine somewhat longer than the
last spine in the first dorsal, and not quite half the length of the
first soft ray; soft rays nearly even throughout, and not equalling
the highest point of the first dorsal. Anal short and somewhat
rounded, commencing beneath the middle of the second dorsal, and
double the height of that fin; its first spine very short and
inconspicuous; second long and moderately stout, but shorter than
the first soft ray by one-third; second soft ray the longest; third
and succeeding ones gradually decreasing. Pectorals narrow and
pointed, shorter than the head; first ray simple, the rest branched;
third, fourth and fifth longest. Ventrals attached a trifle
backwarder than the pectorals, which they do not equal in length;
the spine much slenderer than that of the anal, and rather more than
half the length of the first soft ray. Caudal squarish, but with the
margin a little sinuous.
B. 7; D. 10—1/28; A. 2/8; C. 17; P. 17; V. 1/5.
Length 8 inches 6 lines.
COLOUR.—“Above inclining to coppery, with irregular transverse bars of
brown; beautifully iridescent with violet.”—D. The bars alluded to
by Mr. Darwin are some dark lines which, commencing at the upper
part of the back, pass forwards and downwards in an oblique
direction; they bend more and more downwards as they advance, and
disappear a little below the middle. The whole fish has a metallic
gloss, particularly about the cheeks and gill-covers, and very
visible even in its present state.
_A second specimen_, exactly similar to the above, is nearly twelve
inches in length.
Habitat, Maldonado and Monte Video.
I entertain no doubt of this species being the _C. adusta_ of Agassiz,
figured in Spix’s Fishes of Brazil. It is not described by Cuvier and
Valenciennes, but belongs to their second section of the genus,
characterized by the small spines on the ascending margin, and
especially at the angle, of the preopercle. It seems to be particularly
distinguished by the small scales on some parts of the head, and along
the lateral line where they accompany the larger ones. These characters
have not been overlooked by Agassiz. There are two specimens in the
collection, the larger one taken at Monte Video, the smaller at
Maldonado.