sented in the ‘ Histoire des Poissons,’ and of which there are evident traces, though apparently
m uch eifaced by the action o f the spirit.
Habitat, Maldonado Bay, Rio Plata.
This species, which Cnvier and Valenciennes consider as the Guatucupa of
Margrave, was obtained by Mr. Darwin at Maldonado. M. D'Orbigny had
previously taken it at Monte Video. Tlie only respects in which Mr. Darwin’s
specimen differs from D ’Orhigny’s, is in its having two move rays in the soft
dorsal, aud a slightly longer anal spine, judging from the figure in the ‘ Histoire
des Poissons ; ’ but I cannot imagine that they are distinct on these grounds
only, so exactly do they agree in all tlieir other characters.
CORV IN .I ADUSTA. Jgassiz.
Corviiia adusta, Spix et Àgass. Pisces B razil, p . 126. tab. 70.
F o r m .— G reatest depth beneath the commencement of the first dorsal fin, and equalling one-
fourth of the entire length. B ack somewhat carinated, and moderately arched, forming one
continuous curve with the profile, which falls with considerable obliquity. V entral line nearly
straight, and the abdomen much flattened in front of, and between the ventrals. Length of the
head ju st equalling the depth of the body. Snout obtuse, with two small lobes a t bottom, one
on each side of the extremity, as in several other species of this genus. M outh horizontal, at
the bottom of the snout; when closed, the m a x i l l a r y 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. Jaw s 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 a t bottom somewhat rounded: the ascending margin
rectilineal, sloping rather in advance of a vertical, and distinctly toothed, the teeth becoming
smaller upwards : a t the angle are two stronger teeth or spines, the uppermost directed backwards
and a little downwards, the lowermost downwards and a little backw ards; between
these two teeth there is an interval; the basal m argin 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 term inate in denticles at the
anterior margin. Those on the lateral line have the mucous tubes somewhat ramified, and arc
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.
F irst 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 h alf 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. V entrals attached a trifle backwarder than the pectorals, which they do not
equal in length ; the spine much slenderer than th a t of the anal, and rather more than h alf the
length of the first soft ray. C audal 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 M r. Darwin are some dark lines which, commencing
at the upper part of the back, pass forw’ards 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 lias 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.
H abitat, Maldonado and Monte Video.
I entertain no doubt of this species being tlie 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 he 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 Slaldonado.