Chapter V: Part 5

_Corpus altum, rhomboideum, valdè compressum, squamis minutissimis
obtectum. Linea lateralis anticè sursum paulò arcuata, per totam
longitudinem inermis. Cauda lateribus haud carinatis. Dentes in
utrâque maxillâ uniseriati, tenuissimi, acuti; in linguâ, vomere, et
palatinis, velutini brevissimi. Apertura branchialis amplissima,
membranâ decem-radiatâ. Spinæ quinque liberæ loco pinnæ dorsalis
primæ; spinâ minutâ, præeunte reclinatâ antrorsum flexâ. Dorsalis
secunda, æquè ac analis, continua, sine pinnulis falsis: ante analem
spinæ duæ liberæ. Pectorales parvæ. Ventrales nullæ. Caudalis
profundè furcata, lobis acuminatis, subelongatis._

This new genus belongs to that section of the _Scombridæ_ characterized by having a number of short free spines, instead of a first dorsal fin. It is most nearly allied to _Lichia_, especially to the _L. glaucus_, which it resembles in general form, as well as in many of its particular characters. It has the same reclined spine in front of those which represent the first dorsal, and the same two free spines in front of the anal; also the same form of opercle; the same deeply forked caudal, and small pectorals. But it may be at once distinguished from that genus by the absence of ventrals, of which there is not the least trace: the body is also deeper, rhomboidal rather than oval, and more compressed. In all these respects it agrees better with _Stromateus_, which would seem particularly to meet it in those species, such as the _S. candidus_ and _S. securifer_, which are represented by Cuvier and Valenciennes as having a number of minute truncated spines before the dorsal and anal fins, and which, by virtue of this character, though in the case of the former the spines are not apparent externally, serve manifestly to re-conduct to the section to which _Lichia_ belongs. The discovery of the present genus, therefore, furnishes a more completely connecting link between these two groups.

_Rhynchobdella_ and _Mastacemblus_ agree with _Paropsis_, both in wanting ventrals and in having the first dorsal represented by free spines; but the form of these two genera is so totally different in all other respects, that it is impossible they can be confounded with it.

This new genus is from the east coast of South America.

PAROPSIS SIGNATA. _Jen._

PLATE XIII.

_P. argentea, nitens, summo dorso cærulescente; operculo ad angulum
superiorem maculâ nigrâ signato; pinnis pectoralibus maculis duabus
in axillis et ad radices radiorum, minoribus._

B. 10; D. 5—1/33; A. 2—1/35; C. 17, et circa 5/5— accessar.; P. 21; V.
0.
LONG. unc. 9.

FORM.—Body very much compressed, of a rhomboidal form, the dorsal and
ventral lines rising to an angle at the commencement of the dorsal
and anal fins respectively. Head a laterally compressed cone: tail
becoming suddenly attenuated before the setting on of the caudal
fin, without any keel at the sides. Back sharp and elevated; the
greatest depth contained not more than two and a half times in the
entire length: thickness only one-fifth of the depth. The length and
depth of the head are equal, each being half the depth of the body.
The upper and under profile meet at the extremity of the snout at
nearly a right angle, the former falling in a very regular curve
from the commencement of the dorsal fin. Mouth moderately large, the
commissure reaching to beneath the eye, with the lower jaw
projecting and of considerable strength and thickness. In each jaw a
single row of very fine sharp teeth. The tongue, which is of a
triangular form, free at the tip, and pointed, is rough, with some
extremely fine closely shorn velutine teeth: a small triangular
patch of these last teeth on the front of the vomer, and a narrow
row on each palatine: pharyngeans with rather stronger teeth. The
intermaxillary is very slightly protractile. The maxillary reaches,
when the mouth is closed, to a vertical from the posterior part of
the orbit: it is very visible from without, having only its anterior
portion concealed by the suborbital, and being much dilated at its
posterior extremity, which is in shape somewhat securiform. Eyes
above the middle of the cheek, and nearer the end of the snout than
the posterior margin of the opercle; their diameter rather more than
one-fifth the length of the head: the suborbital forms a narrow band
beneath each. Nostrils half-way between the eyes and the end of the
snout; the anterior orifice round; the posterior, which is the
larger one, oval. Preopercle with the ascending margin nearly
vertical; the angle at bottom rounded. The opercle and subopercle
together present a rounded margin posteriorly, though at the upper
portion there are two small blunt points distinguishable by the
finger, between which there is a very shallow notch: the line of
separation between these two bones descends obliquely forwards to a
little above the rounded angle of the preopercle, where it meets the
line of the interopercle, which descends obliquely backwards:[26]
all the margins of the opercular pieces entire. Gill-opening very
large, the aperture reaching to beneath the anterior margin of the
eye: the membranes, each of which has as many as ten rays,[27] cross
a little over each other, and are not united to the isthmus.

_Fish. Pl. 13._

_W. Hawkins del^t._

_Paropsis signata. Nat. Size._
]

Snout, jaws, and cheeks, as well as the several pieces of the
gill-cover, without scales:[28] body covered with extremely minute
ones, of an oval form, longer than broad, marked with concentric
circles, and entire on the margin. The lateral line is slightly
arched above the pectoral, and its course a little undulating, but
it descends gradually to near the middle of the body, whence it runs
straight to the caudal.

The first dorsal is represented by five short free spines, each
capable of separate motion, and each furnished with its own
membrane; in advance of them is a somewhat smaller reclined spine
with its point directed forwards: the first erect spine is above the
middle of the pectoral, and distant from the end of the snout nearly
one-third of the entire length. Beyond the five free spines, and
immediately before the commencement of the second dorsal is another
small spine closely pressed down, and almost concealed beneath the
skin, pointing backwards. The second dorsal, which has also at its
anterior edge a small spine one-third the length of the first soft
ray, commences at the middle point of the entire length, caudal
excluded. The general form of this fin is similar to that of the
genus _Lichia_, long, with the anterior portion elevated; the
greatest height about one-fourth of the depth, or hardly so much.
The anal answers exactly to the second dorsal in form and extent,
and is preceded by two free spines, separated from it by a small
space, besides a longer one at its anterior edge. Caudal forked
nearly to the base, where there are a number of minute scales; the
lobes equal, pointed, and moderately elongated, each contained about
four times and one-third in the entire length. Pectorals attached at
about the middle of the depth, a little behind the opercle; of a
somewhat triangular form, small, their length not much exceeding
half that of the head. No trace of ventrals whatever.

COLOUR.—“Uniform bright silvery, the ridge of the back bluish: a black
patch on the gill-cover, and another under the pectoral fin.”—D.—The
first of the patches alluded to by Mr. Darwin is very conspicuous,
and is situate at the upper angle of the opercle, immediately in
advance of the commencement of the lateral line. The second may be
described as consisting of two distinct spots; one at the root of
the upper rays, and completely in the axilla; the other, a small one
of an elongated form, immediately beneath the lowest ray, and partly
visible without raising the fin. The elevated portion of the second
dorsal is also dusky, and a faint edging of this colour runs for a
short way along the margin of this fin. The anal is pale.

Habitat, Northern coast of Patagonia.

I have termed this species _signata_, in reference to the black patch on the opercle, which is a conspicuous character. The only specimen in the collection was obtained by Mr. Darwin at Bahia Blanca, on the coast of North Patagonia.

1. CARANX DECLIVIS. _Jen._
PLATE XIV.

_C. corpore elongato, altitudine quintam, capite quartam partem
longitudinis æquante; maxillâ inferiore longiore; lineâ laterali
infra quintum radium dorsalis secundæ subito declivi, per totam
longitudinem armatâ, laminis 82 altioribus quam longis, ubique
æqualibus; spinâ reclinatà ante pinnam dorsalem parvâ, mucrone tamen
nudato; pectoralibus ultra pinnulam analem, et prope ad analem
ipsam, pertingentibus._

B. 7; D. 8—1/35; A. 2—1/30; C. 17, &c.; P.21; V. 1/5.
LONG. unc. 7. lin. 10.

FORM.—Rather more elongated than the _C. trachurus_ of the British
seas. Greatest depth one-fifth of the entire length: head one-fourth
of the same: thickness about half the depth. Diameter of the eyes a
little less than one-third the length of the head. Lateral line
bending downwards more suddenly, and at a more backward point than
in that species. The bend commences in a line with the fifth ray of
the second dorsal, and is entirely comprised within a space equal to
that occupied by four fin-rays,[29] so that opposite the ninth ray
it again advances in a horizontal line. The posterior portion about
equals in length the anterior, the bend being included in this last.
The laminæ which protect the lateral line, and which extend
throughout its whole length, are well developed, and everywhere of
the same breadth; this breadth equalling nearly, but not quite,
one-third the depth of the body. In number they are eighty-one or
eighty-two; of which the last thirty-eight or forty, forming the
posterior portion of the line, have keels terminating backwards in
sharp spines: these spines are at first small and inconspicuous, but
gradually increase in size as they advance towards the thinnest part
of the tail, where they are sharpest and most developed.

In most of its other characters this species so closely resembles the
_C. trachurus_, as to render a detailed description unnecessary. The
reclined spine before the first dorsal, however, is smaller, though
the point is sharp and exposed: also the number of rays in the
second dorsal and anal is greater by five in each fin. The length of
the second dorsal is two and a half times that of the first. The
pectorals are long, narrow, and pointed; a little shorter than the
head, or rather less than one-fourth of the entire length; when laid
back, they reach beyond the anal finlet, and very nearly to the
commencement of the true anal itself.

COLOUR.—Not noticed in the recent state. So far as can be judged from
a specimen in spirits, the colours appear to have been similar to
those of the _C. trachurus_; and there is the same black spot on the
upper part of the opercle.

_Fish. Pl. 14._

_W. Hawkins del^t._

_Caranx declivis. Nat. Size._
]

_Fish. Pl. 15._

_W. Hawkins del^t._

_Caranx torvus. Nat. Size._
]

Habitat, King George’s Sound, New Holland.

Cuvier and Valenciennes have noticed several variations of form occurring in different specimens of the _C. trachurus_, from different seas, which they have not ventured to raise to the rank of species. That the one here described is entitled, however, to this distinction, I can hardly entertain a doubt. The suddenness of the bend in the lateral line, and the more backward point at which the bend commences; the larger number of laminæ which protect it; and also the larger number of rays in the second dorsal and anal; all seem to indicate a specific difference. Whether it be identical with any of the varieties noticed by them is uncertain; but it seems to be distinct from the only one they speak of as having been received from New Holland, in which the number of laminæ did not exceed seventy-three. I have called it _declivis_, in reference to the character of the lateral line above alluded to. It was obtained by Mr. Darwin in Princess Royal Harbour, in King George’s Sound.

2. CARANX TORVUS. _Jen._

PLATE XV.

_C. corpore crassiusculo, subelongato; altitudine vix quartam partem,
longitudinis æquante, capite quartam superante; maxillâ inferiore
longiori; oculis magnis; suborbitalibus venis nonnullis
subparallelis obscuris notatis; lineâ laterali parum deflexâ, anticè
squamis parvis inermibus, posticè laminis carinatis 35 vel 36 tectâ;
spinâ reclinatâ ante pinnam dorsalem sub cute occultâ; pectoralibus
longis, falcatis, ad initium pinnæ analis prope pertingentibus._

D. 8—1/26; A. 2—1/22; C. 17, &c.; P. 21; V. 1/5.
LONG. unc. 11. lin. 9.

FORM.—Thicker and deeper in the body than the _C. trachurus_. The
greatest depth a little less than one-fourth of the entire length;
the thickness exceeding (but by a very little) half the depth. Head
large; its length a little more than one-fourth of the entire
length; its height or depth, taken in a line forming a tangent to
the posterior part of the orbit, less than its own length by
two-sevenths. Eyes large; their diameter very nearly one-third the
length of the head; partially covered at the sides by two fatty
membranous veils, as in several other species. The ventral line of
the body is rather more curved than the dorsal, and the upper
profile in like manner a little more approaching to rectilineal than
the lower. The lower jaw a little the longer, and ascending to meet
the upper. Maxillary reaching not quite to beneath the middle of the
eye; its extremity truncated in the form of an arc, with the
curvature inwards. In each jaw a single row of very fine, minute,
closely set teeth; two small patches on the anterior extremity of
the vomer, a band on each palatine, and one on the tongue, all
closely shorn velutine. Suborbital, on each side of the extremity of
the snout, marked with several nearly parallel dark-coloured veins.
Preopercle with the angle very much rounded; the limb broad,
slightly striated or veined, and not separated from the cheek by any
salient ridge. The other pieces of the gill-cover taken together are
bounded posteriorly by a sinuous and very irregular margin, the
notch in the bone at the upper part of the opercle being nearly
semicircular, beneath which is an obtuse point, whence the obliquely
descending margin first slopes slightly inwards, then passes
outwards to form another blunt point lower down, then slopes inwards
again. The course taken by the margin of the membrane in some
measure follows that of the bone, but the sinuosities and salient
angles are more rounded. Cheeks and opercle scaly, as well as the
cranium and forehead between the eyes.

The lateral line does not deviate very much from rectilineal. The
deflection, such as it is, may be said to commence in a line with
the termination of the first dorsal, and to end beneath the first
third of the second dorsal. Up to this point, the scales which
cover it are small and round; but they then begin gradually to
enlarge, and to assume a keel terminating posteriorly in a short
spine: these scaly laminæ continue increasing in size till they
arrive beneath the last quarter of the fin, where they are most
developed; none of them, however, are very large, and even here
they do not extend over the whole breadth of this part of the
tail, nor their own breadth exceed one-eighth of the greatest
depth of the body. After passing the dorsal and anal fins, they
rapidly diminish as they approach the caudal. The entire number of
laminæ may be set at thirty-five or thirty-six; but as it is
difficult to fix the exact point where they commence, it will vary
according as the computation is made more or less in advance. The
anterior portion of the lateral line, bend included, is a little
longer than the posterior.

The reclined spine in this species is entirely concealed beneath the
skin. The pectorals are long and falcate, terminating in a sharp
point: their length nearly equals that of the head, or about
one-fourth of the entire length: when laid back, they reach over
the anal finlet, and very nearly to the commencement of the true
anal. The ventrals are attached a little behind the pectorals, and
are only half as long. The other fins are much as in the other
species of this genus. The height of the anterior part of the
first dorsal equals exactly half the depth. The lobes of the
caudal are one-fifth of the entire length.

COLOUR.—Not noticed in the recent state. _In spirits_; silvery on the
abdomen and lower half of the sides, passing above the middle, and
on the back, into pale lead blue, tinged with gray and brownish:
fins pale greyish brown. No conspicuous markings, except the usual
spot on the notch of the opercle, which, however, is small, and
confined entirely to the membrane.

Habitat, Tahiti.

This species belongs to the second section adopted by Cuvier and Valenciennes in this genus; or that in which the form of the body resembles that of the _C. trachurus_, but in which the laminæ on the lateral line only extend over the posterior portion, the anterior being smooth and simply covered with small scales. But it will not exactly accord with any of the species described by those authors. It seems to approach most nearly the _C. Plumieri_; but though the eyes are of considerable size, they are not quite so large as they are represented to be in that. There seem, in fact, to be several species characterized by large eyes. Spix and Agassiz have figured one from America under the name of _C. macrophthalmus_; and under the same name Ruppell has figured another from the Red Sea. Both these, however, appear likewise different from the one here described, at the same time that their different geographic range renders their identity _à priori_ improbable. The present one was taken by Mr. Darwin at Tahiti.

3. CARANX GEORGIANUS. _Cuv. et Val._

Caranx Georgianus, _Cuv. et Val._ Hist. des Poiss. tom. ix. p. 64.

FORM.—Of an oval compressed form, with the back elevated. Greatest
depth one-third of the entire length, caudal excluded: thickness not
half the depth: head one-fourth of the entire length, caudal
included. Profile ascending obliquely, and in nearly a straight
line, to meet the dorsal curve. Upper jaw a little the longer. The
maxillary, which is truncated and cut nearly square at its posterior
extremity, not quite reaches to beneath the anterior margin of the
orbit. In each jaw a row of about thirty-five teeth, which are
small, somewhat cylindrical, set regularly, nearly equal, and rather
blunt at the point; very little trace of any secondary row, simply
four or six smaller ones behind those in the middle of the upper
jaw, and perhaps in the lower also, but they are not very obvious. A
triangular patch of velutine teeth on the vomer, and a narrow band
of the same on each palatine; also on the tongue: these last,
however, very closely shorn. Eyes a little above the middle of the
cheek, but exactly half-way between the end of the snout and the
posterior margin of the opercle; their diameter one-fourth the
length of the head. Preopercle rounded at the angle; its limb
separated from the cheek by a slight but not very salient ridge.
Opercle with the notch at the upper part not very deep; the
obliquely descending margin straight.

The lateral line follows the curvature of the back until it arrives
beneath the middle of the second dorsal, at which point it becomes
straight, and the scales gradually pass into carinated spinous
laminæ. These laminæ, however, are very little developed
anteriorly to the last quarter of that fin; and even beneath the
end of it, where they are largest, they do not extend over more
than half the breadth of the tail, nor does their own breadth
exceed one-seventeenth of the greatest depth of the body. The
number of them is from twenty to twenty-five, according to the
point at which the reckoning commences, the transition from the
scales to the laminæ being very gradual. The pectorals are falcate
and sharp-pointed, and one-fourth of the entire length, caudal
included. The height of the anterior part of the dorsal is
contained two and a half times in the depth. The lobes of the
caudal are contained four times and three quarters in the entire
length.

D. 8—1/27; A. 2—1/24; C. 17, &c.; P. 20; V. 1/5.
Length 7 inches 6 lines.

COLOUR.—Not noticed in the recent state. The colour of the back and
upper part of the sides appears to have been bluish grey, with steel
and other reflections, and was probably very brilliant in the living
fish: belly silvery. No markings, except a conspicuous black spot on
the upper part of the opercle.

_A second specimen._—Differs in no respect from the above, excepting
in having one ray less in the second dorsal and anal fins.

Habitat, King George’s Sound, New Holland.

I entertain not the least doubt of this species being the _C. Georgianus_ of Cuvier and Valenciennes; but as the notice of it in the “Histoire des Poissons” is extremely brief, I have deemed it advisable to annex a detailed description. Both Mr. Darwin’s specimens are from King George’s Sound, where the species was first discovered by MM. Quoy and Gaimard.

SERIOLA BIPINNULATA. _Quoy et Gaim._

Seriola bipinnulata, _Quoy et Gaim._ Voyage de l’Uranie (Zool.) p. 363, pl. 61. f. 3. —— —— _Cuv._ Regne An. (2d Edit.) tom. ii. p. 206.

FORM.—Elongated, and fusiform. Greatest depth contained four times and
a half in the length, measuring this last to the base of the caudal
fork. Head four times and a quarter in the same: depth of the head
not quite once and three quarters in its own length; the cheeks
nearly vertical. Snout pointed: profile straight, and but slightly
falling. Lower jaw a little longer than the upper, the commissure
reaching to beneath the orifices of the nostrils: maxillary very
conspicuous, and greatly dilated at its posterior extremity. A band
of minute velutine teeth in each jaw, broadest in front; a disk of
similar teeth on the vomer, and a band on each palatine. Eyes large;
their diameter one-fifth the length of the head; situated a little
above the middle of the cheek, and a little nearer the end of the
snout than the posterior margin of the opercle; exactly two
diameters between the eye and the end of the lower jaw. The nostrils
consist of two small, round, closely approximating orifices, the
anterior one partially covered by a membrane; situated rather nearer
the eye than the extremity of the snout. Preopercle with the
ascending margin vertical, and the angle at bottom rounded; the limb
very broad, and marked with veins, and between the veins, along the
basal margin, with fine striæ. The rest of the pieces of the
gill-cover, taken together, present a rounded and regularly curved
outline posteriorly; the line of separation between the opercle and
subopercle ascends obliquely backwards from a point about two-thirds
down the posterior margin of the preopercle; that between the
subopercle and the interopercle (which last is well developed)
passes downwards and backwards, forming an angle of about 45° with
the axis of the body. Branchial aperture large; the membrane deeply
cleft. Snout, jaws, and pieces of the opercle, smooth and naked;
cheeks scaly, the scales on the upper part of the cheek, between the
eye and the upper angle of the preopercle, being of a narrow pointed
form. The scales on the body are of a moderate size, oval, marked
with fine concentric circular striæ, with a fan of coarser diverging
striæ on their concealed portion. The lateral line is smooth
throughout its length, and runs nearly straight from the upper angle
of the opercle to the caudal, its course being a little above the
middle.

The first dorsal commences at about one-third of the entire length,
measuring this last as before: it is low and inconspicuous,
consisting of only six weak spines, of which the third and fourth
are somewhat the longest, but whose length is less than one-fifth
of the depth of the body. The length of the fin itself is rather
less than half the depth. Second dorsal closely following, and
much longer; of the form usual in this family, with the anterior
portion elevated and somewhat triangular, but beyond the ninth ray
low and even: its spine half the length of the first soft ray: its
greatest elevation contained about two and a half times in the
depth. The last two rays of this fin are broke away from the rest,
with an intervening space, to form a spurious finlet, and are
rather longer, the last especially, than those which precede. The
anal commences opposite the fourteenth ray of the second dorsal,
and is similar in form to that fin, but of course shorter, and
also less elevated at its anterior extremity: finlet and the
intervening space exactly corresponding. Caudal deeply forked; the
lobes very long and pointed, each equalling nearly one-fourth of
the entire length; the middle rays not one-fourth the length of
the lateral ones. Pectorals attached a little below the middle; in
length a little exceeding half that of the head. Ventrals about
the same size as the pectorals, but attached a little further
back. A slight elevation at the sides of the tail, but no distinct
keel, properly so called.

D. 6—1/24—I; A. 1/16—I; C. 17, &c.; P. 20; V. 1/5.
Length 18 inc. 3 lines.

COLOUR.—“Band on the side azure blue; above a duller greenish blue;
beneath two greenish metallic stripes: lower half of the body snow
white.”—D. No trace of the longitudinal stripes remains in the dried
skin.

Habitat, Keeling Island, Indian Ocean.

A tolerably exact figure of this species occurs in the Zoological Atlas of Freycinet’s Voyage, but I can find no notice of it in the “Histoire des Poissons” of Cuvier and Valenciennes. Although referred by Cuvier in his “Regne Animal” to _Seriola_, it rather departs from that genus in some of its characters. Independently of the spurious finlets in the dorsal and anal fins, which separate it from all the other species, I see no trace of any reclined spine before the first dorsal, nor of two free spines before the anal; in both which respects _Seriola_ is said to resemble _Lichia_. Possibly, however, as Mr. Darwin’s specimen is a dried skin, these characters may have been destroyed in the process of preparation. And to the same cause, perhaps, is to be attributed the circumstance of my not being able to observe more than one spine in the true anal, Quoy and Gaimard mentioning two. On the other hand, these naturalists appear to have overlooked the narrow pointed scales on the upper part of the cheeks, which are of a different character from the scales on the body.

Mr. Darwin’s specimen of this species was obtained at the Keeling Islands. The one figured in Freycinet’s Voyage was procured at Papua or New Guinea. It probably, therefore, has a considerable range over the Indian Ocean.

PSENES ——?

Psenes leucurus, _Cuv. et Val._? Hist. des Poiss. tom. ix. p. 197.

Mr. Darwin’s collection contains two individuals of a species of _Psenes_, in reference to which his notes state that they were taken in Lat. 17° 12′ S., Long. 36° 33′ W., a hundred and twenty miles from the nearest land above water, though shoals were considerably nearer. They do not measure more than one inch eight lines in length; and from their small size, and their not being in a very firm state of preservation, it is hardly possible to say whether they are new or not. In form, they differ but little from the _P. cyanophrys_ of Cuvier and Valenciennes: still they are evidently not that species, and one point of difference consists in the lateral line, which terminates beneath the end of the second dorsal, and is not carried on to the caudal, as represented in the figure of the above species in the “Histoire des Poissons:” the eye too appears rather larger; the forehead is hardly so much elevated, and the pectorals are shorter than the head. Perhaps it may be the _P. leucurus_ of the above authors; though this species is from the Indian seas, so that its range must be considerable if the same. The description of the _P. leucurus_ in the “Histoire des Poissons” is too short to determine this point. It is said to have been so named on account of its whitish tail, all the other fins being black. In the present species, the fins are likewise black, or at least dusky, except the caudal, which Mr. Darwin’s notes, taken from the recent fish, state to have had “a pink tinge.” In the same notes it is added,—“belly silvery white mottled with brownish black; sides bluish with dusky greenish markings; iris yellow, with dark blue pupil.” The fin-ray formula is as follows:

D. 10—1/27; A. 3/27; C. 17, &c.; P. 17 or 18; V. 1/5.

Though these specimens are small, they have the appearance of being nearly full-sized. Cuvier and Valenciennes state that their specimens of the _P. leucurus_ do not exceed two inches in length.

STROMATEUS MACULATUS. _Cuv. et Val.?_

Stromateus maculatus, _Cuv. et Val._ Hist. des Poiss. tom. ix. p. 296.

FORM.—General form so extremely similar to that of the _S. Fiatola_ of
the Mediterranean as to preclude the necessity of a detailed
description. Greatest depth one-third of the length: head one-fifth
of the same. Number of rays in the dorsal and anal fins somewhat
greater than in the _S. Fiatola_. The height of the dorsal also a
little greater, being contained about three times and a half in the
depth: the fifth and sixth soft rays longest. Fleshy part of the
tail more slender. Pectorals about the length of the head.

B. 6; D. 7/41; A. 5/40; C. 17, besides several short; P.23; V. 0.
Length 8 inches 6 lines.

COLOUR.—“Silvery blue above, with regular circular leaden spots.”—D.
The spots are small, and of nearly equal size: they prevail from the
back downwards to about the middle of the depth, and advance a
little on the base of the dorsal fin. The arrangement of them is
much as described in the “Histoire des Poissons.”

Habitat, Chiloe, West Coast of S. America.

It is just possible that this may not be specifically the same as the _S. maculatus_ of Cuvier and Valenciennes, but it comes so extremely near that species that I do not feel authorised in describing it as distinct without seeing more specimens. It is stated by the authors above mentioned, that the fin-ray formula of the _S. maculatus_ is the same as that of the _S. Fiatola_: in the specimen here described, the number of rays in the dorsal and anal fins appear to me somewhat greater; but as the spines of these fins are very minute at their commencement, and not readily counted, nor very distinguishable from the soft rays, perhaps the discrepancy may arise from a difference in the mode of computation. What is more to be noted is, that the spots, although they agree in form and mode of arrangement, are said by Mr. Darwin, in his notes taken from the recent fish, to have been “leaden;” whereas it is stated in the “Histoire des Poissons” that they are “yellow.” Perhaps they may vary in colour according to the period of the year. There is likewise a difference in locality as regards latitude. The _S. maculatus_ is said to be common in the market at Lima, and to have been brought also, both by M. D’Orbigny and M. Gay, from Valparaiso. Mr. Darwin’s specimen, however, was taken as far south on the western coast of S. America as Chiloe.

Mr. Darwin’s collection contains another specimen, either of the same species as that described above, or one so extremely similar to it as not to be distinguishable in the case of this specimen, which is in too bad preservation to admit of an accurate description of it being given. The following, however, are Mr. Darwin’s notes taken from the recent fish:—

COLOUR.—“Whole body silvery; upper part of the back iridescent blue,
lower greenish; spotted with coppery-lead circular patches.”—D.

This specimen measures ten inches and a half in length. It will be observed that the colour of the spots is still said to have been “lead,” though inclining to coppery. It was not taken at the same place as the other, but at Port St. Julian, in central Patagonia; if therefore they are both referable to the _S. maculatus_, this species will have been proved to have a wide range in point of latitude, and also to occur on both sides of the S. American Continent, which is remarkable, considering that it is found so high up the western side as Lima.

FAMILY.—TEUTHYDIDÆ.

1. ACANTHURUS TRIOSTEGUS. _Bl. Schn._

Acanthurus triostegus, _Cuv. et Val._ Hist. des Poiss. tom. x. p. 144. —— Hirudo, _Benn._ Fish of Ceyl. pl. xi.

This species, which appears to be well known, and to have been described by several authors, was found by Mr. Darwin on coral reefs at the Keeling Islands. Cuvier and Valenciennes observe that it has a wide range through the Indian and Pacific Oceans. Mr. Darwin’s specimen agrees in every respect with the description in the “Histoire des Poissons,” except in having one ray more in the anal fin: its length is not quite five inches.

2. ACANTHURUS HUMERALIS. _Cuv. et Val._

Acanthurus humeralis, _Cuv. et Val._ Hist. des Poiss. tom. x. p. 170.

FORM.—General form oblong-oval. Greatest depth just behind the
insertions of the pectorals; contained exactly twice in the length
of the oval of the body (measuring this last from the end of the
snout to the base of the caudal spine), and three times in the
entire length (measuring this last to the extremities of the lobes
of the caudal fin.) Profile convex before the eyes, whence it
descends nearly vertically to the mouth. Height of the head a little
exceeding its own length. Eyes very high in the cheeks, and in front
of each a grooved line passing horizontally forwards towards the
nostrils; which last consist of two small round orifices, the
anterior one larger than the other, and partially covered by a
membranous flap. There are seventeen teeth in the upper jaw, and
sixteen in the lower: those above have the cutting edges crenated,
and likewise the lateral edges for nearly half-way down; this most
observable in the middle ones, in which the crenations amount to
eight or ten in number: those below similar, but with the crenations
not quite so numerous, and in some of the teeth at the sides of the
jaw almost confined to the cutting edges. Scales minute; those taken
from the middle of the body appear of an oblong form, their apical
portions dotted, and ciliated with from twelve to eighteen very
minute denticles, their surface marked with extremely fine delicate
striæ, not distinguishable without a strong lens.

The lateral line follows the curvature of the back; at about
one-fifth of the depth. The spine on the sides of the tail is
strong, and sharp-pointed, and very slightly bent. No reclined
spine before the dorsal. Both the fin just mentioned and the anal
have their soft portions terminating posteriorly in rather an
acute angle: also both have a scaly membrane at the base, and rows
of minute scales between the soft rays extending for about
one-third or more of their length. The first ray of the anal is
very minute, and so much concealed in the skin as to be easily
overlooked. The filaments of the caudal are sharp-pointed, and
extend as far again as the middle rays: the upper one rather
longer than the other. The pectorals are contained three times in
the length of the oval of the body. Ventrals attached a little
further back, sharp-pointed, and terminating in the same vertical
line with the pectorals, both being laid back.

D. 9/23; A. 3/23; C. 16, &c.; P. 16; V. 1/5.
Length, to the end of the caudal lobes, 7 inches.

COLOUR.—The colours appear to have been exactly as described in the
“Histoire des Poissons.” Mr. Darwin’s notes taken from the recent
fish state, “splendid verditer blue and green;” but do not enter
into the details of the markings.

Habitat, Tahiti.

Obtained at Tahiti, where it had been previously found by MM. Lesson and Garnot. Mr. Darwin’s specimen accords with the characters given by Cuvier and Valenciennes, except in having two soft rays less in the dorsal, and one less in the anal. Their description, however, is not very detailed.

FAMILY.—ATHERINIDÆ.

1. ATHERINA ARGENTINENSIS. _Cuv. et Val.?_

Atherina argentinensis, _Cuv. et Val._ Hist. des Poiss. tom. x. p. 350.

FORM.—Depth exactly one-sixth of the length, measuring this last to
the end of the middle caudal rays. The length of the head is five
and a half times in the same, measuring this last to the end of the
caudal lobes. Thickness of the body at least half the depth. Head
broad and flat, its breadth across the crown behind the eyes
equalling three-fourths of its depth. Snout rounded horizontally,
but sharp vertically. The profile is perfectly horizontal; and one
uniform straight line extends from the extremity of the upper jaw to
the commencement of the second dorsal. Ventral line swelling a
little outwards, with its greatest curvature about the middle. Upper
jaw a very little longer than the lower, which ascends to meet it at
an angle of 45°: gape not reaching more than half-way to the eye, at
first horizontal, afterwards deflexed. In each jaw two rows of
teeth, stronger and more developed than usual in this genus, widely
asunder, and at irregular intervals: in the upper jaw these two rows
are equal; in the lower the outer row is stronger than the inner:
the outer row above contains about thirty-two or thirty-three teeth;
that below twenty-six or twenty-eight: no teeth on the tongue, and
scarcely any that can be seen on the vomer or palatines, though a
slight roughness can be felt on the last two. Eyes moderately large;
their diameter a very little less than one-fourth the length of the
head; situate a little in advance of the middle point, and also a
little above the middle of the depth. Cheeks and gill-covers scaly.
Form of the scales of the body, as well as the number of
longitudinal rows, exactly as stated by Cuvier and Valenciennes. The
same may be said of the lateral line, and the situation of the
dorsal fins. The second dorsal and anal terminate in the same
vertical line. Pectorals exactly the length of the head. Ventrals
attached immediately below the tips of the pectorals. Breadth of the
silver band, which runs straight along the middle of the sides,
exactly one-fifth of the greatest depth of the body.

D. 5—1/9; A. 1/19; C. 17, &c.; P. 15; V. 1/5.
Length 8 inches.

COLOUR.—“Silvery, with a silver lateral band: above bluish grey.”—D.
In spirits, it appears greenish brown, becoming deeper above the
silver band and on the ridge of the back: the free margins of the
scales are finely dotted with black: the rays of the caudal have
been worn at the tips, but there is a trace of the dusky edging
noticed by Cuvier: the pectorals are also stained with dusky.

Habitat Maldonado.

I conceive there is but little doubt of this being the _A. Argentinensis_ of Cuvier and Valenciennes; but as the description in the “Histoire des Poissons” is short, I have thought it advisable to give a more detailed one of the above specimen. Mr. Darwin took it at Maldonado, where he states that it is very common, adding that it is sometimes found in brackish water. M. D’Orbigny had also found it previously at the mouth of the Rio Plata.

2. ATHERINA MICROLEPIDOTA. _Jen._

PLATE XVI. Fig. 1. Nat. size.
Fig. 2. _a_, _b_. Magnified scales.

_A. gracilis; corporis altitudine partem octavam, capite quintam,
longitudinis æquante: oculis mediocribus: maxillis subæqualibus, parum
protractilibus; commissurâ primum horizontali, deinde paulo deflexâ,
haud oculos attingente: dentibus velutinis, serie externâ supra
subtusque fortiori: dorsali primâ omnino pone ventrales reclinatas
locatâ: squamis parvis, seriebus longitudinalibus octodecim ad minimum
dispositis._

D. 5—1/11; A. 1/17; C. 17, &c. P. 15; V. 1/5.
LONG. unc. 4.

FORM.—More slender and elongated than the generality of the species in
this genus. Greatest depth not more than one-eighth of the entire
length. Head one-fifth of the same. Greatest thickness (in the
region of the gills) equalling two-thirds of the depth, or rather
more. Ventral line of the body scarcely more curved than the dorsal.
The upper profile falls, though very slightly, from the nape to the
mouth, and the lower profile inclines upwards to meet it at about
the same degree of curvature. Head broad, its breadth across the
crown nearly equalling its depth. Snout horizontally rounded. Jaws
nearly equal; not so protractile as in some other species: the
commissure of the lips at first horizontal, but posteriorly
inclining a little downward, and scarcely reaching more than
half-way to the eye. In each jaw two rows of slender very distinct
teeth, with traces of a third or even fourth row above, towards the
middle: outer row longest and most conspicuous, consisting, in the
upper jaw, of from forty-five to fifty teeth; in the lower of
scarcely more than twenty-five. No teeth that can be seen on the
vomer or palatines, though a slight roughness can be felt on both.
Eyes of moderate size; their diameter rather more than one-fourth
the length of the head; almost entirely before the middle, as well
as above it: space between the eyes flat, and exceeding the diameter
by about one-third: a slightly elevated line on each side of this
space, but no other conspicuous sculpture. Opercle with the
descending margin sloping obliquely forwards.

Crown, cheeks, and gill-covers scaly, the scales on the crown
extending as far as the eyes. Scales on the body small, the number
of longitudinal rows amounting to eighteen or twenty: in form
nearly square, the length a little exceeding the breadth, the
superficies marked with numerous very distinct concentric lines,
the basal half with a fan of from four to six deeper-cut striæ,
the basal margin rather sinuous, and obsoletely crenate where the
striæ meet it. No lateral line very distinguishable.

_Fish. Pl. 16._

_Drawn from Nature on Stone by Waterhouse Hawkins._
]

_1. Atherina microlepidota._ _Nat. Size._
_1a._ _1b._ „ „ _magnified Scales._
_2 Atherina incisa._ _Nat. Size._
_2a._ „ „ _magnified Scale._
_2b._ „ „ _Twice Nat. Size._

First dorsal small and delicate, commencing exactly at the middle
point of the entire length, measuring this last to the bottom of
the caudal fork, and in a line with the tips of the ventrals,
these last fins being laid back. Space between the first and
second dorsals a little exceeding two-thirds of the depth of the
body. Length and height of the second dorsal equal to each other,
and also to the space just alluded to. From the end of the second
dorsal to the commencement of the caudal is exactly one-sixth of
the entire length. The posterior half of the anal nearly answers
to the second dorsal, but the two fins do not terminate exactly in
the same line, the dorsal extending a little the furthest. Caudal
forked for about half its length. Pectorals about two-thirds the
length of the head. Ventrals attached at a point beyond the
extremity of the pectorals. Breadth of the silver band about
one-fifth the depth of the body.

COLOUR.—Not noticed in the recent state. In spirits, the back and
sides above the silver band are brownish, with the contour of each
scale marked out by black dots. All below the band appears to have
been silvery. The band itself is not very brilliant. Both the
dorsals, as well as the caudal, are dusky: anal and ventrals pale.

A _second specimen_ does not differ from the above, excepting
slightly in the fin-ray formula, which is as follows:

D. 5—1/10; A. 1/15; &c.

Habitat, Valparaiso.

This species was found by Mr. Darwin at Valparaiso in fresh water, in the month of August. It would seem to be nearly allied to the _A. laticlavia_ of Cuvier and Valenciennes, brought from the same locality by M. D’Orbigny; but, judging from the short description in the “Histoire des Poissons,” it is more elongated, and has the head longer in relation to the depth of the body; also has the silver band narrower. In the _A. laticlavia_, the head is said to be equal to the depth, and to be contained six times in the entire length; the breadth of the silver band to be greater than in any other species. In the _A. microlepidota_, the depth is one-eighth and the head one-sixth of the length: the silver band not broader than in the _A. argentinensis_ and some others. The colouring also of the fins appears different in the two species.

3. ATHERINA INCISA. _Jen._

PLATE XVI. Fig. 2. Nat. size.
Fig. 2. _b._ Twice nat. size.
Fig. 2. _a._ Magnified scale.

_A. gracillima; corporis altitudine partem vix nonam, capite sextam, longitudinis æquante: oculis mediocribus: maxillis æqualibas, valde protractilibus; commissurâ primum horizontali, posterius deflexâ: dentibus velutinis, in maxillâ inferiore minutissimis: dorsali primâ omnino pone ventrales reclinatas locatâ: squamis mediocribus, seriebus longitudinalibus duodecim ad maximum dispositis, marginibus liberis inciso-crenatis; vittâ laterali nitidè argenteâ._

D. 5—1/8; A. 1/17; C. 17; P. 12; V. 1/5.
D. 5—1/9; A. 1/19; &c.—
D. 6—1/10; A. 1/19; &c.—
LONG. unc. 2. lin. 6.

FORM.—Still more slender and elongated than the last species. Greatest
depth scarcely one-ninth of the entire length: head one-sixth.
Dorsal and ventral lines very little curved. General characters of
the head, snout and mouth, as in the _A. microlepidota_, but the
jaws more protractile. A row of minute velutine teeth in each jaw
most developed above. Eyes moderately large; their diameter nearly
one-third the length of the head; the space between them just equal
to their diameter. Opercle with the posterior margin nearly
vertical. Scales larger than in the _A. microlepidota_; the number
of longitudinal rows not exceeding twelve: their form different, and
rather peculiar, the anterior or free edge of each scale in some
instances presenting two or three processes, separated by deep
incisions; in others being irregularly notched or jagged, according
to the spot whence taken: the surface is marked with concentric
lines, but there is no fan of striæ on the basal half: the breadth
of the scale a little exceeds its length, and the basal margin is
irregularly sinuous.

First dorsal answering to the space between the tips of the reclined
ventrals and the anal. Length of the second dorsal exceeding the
intermediate space between it and the first. From the end of the
second dorsal to the caudal is rather more than one-fifth of the
entire length. Depth of the caudal fork not exceeding one-third
the length of the fin. The anal commences in an exact line with
the termination of the first dorsal: rather less than its
posterior half answers to the second dorsal. Pectorals rather
long, measuring nearly one-sixth of the entire length. Breadth of
the silver band one-fourth the depth of the body.

COLOUR.—“Body semitransparent, colourless; with a bright silver band
on each side; also marked with silvery about the head.”—D. The band
is remarkably bright, and well-defined, much more so than in the
last species.

I have ventured to consider this as a new species, though none of the specimens in the collection, amounting to three in number, exceed two inches and a half in length, and are probably not full-sized. The form of the scales is so peculiar, that if it were only the young of some described species, it could hardly fail to be identified by such a character, which is not likely to be affected by age, nor to have escaped the notice of an observer. Yet I can find none answering to it in the “Histoire des Poissons.” The silvery band also is remarkably bright; though the slenderness of the body, another of its peculiarities, is perhaps due to immaturity. The fin-ray formula is somewhat different in the three specimens, as shown above, but in other respects they are similar.

Mr. Darwin’s notes state that this species was taken in the month of September, in 39° S. Lat., 61° W. Long., several miles from the land. This last circumstance, indeed, would seem to indicate that the specimens were not so very young, as the fry of most fish keep close in shore.

FAMILY.—MUGILIDÆ.

1. MUGIL LIZA. _Cuv. et Val.?_

Mugil liza, _Cuv. et Val._ Hist. des Poiss. tom. xi. p. 61.

FORM.—Elongated: the depth contained about five and a half times in
the entire length: the head exactly five times: height of the head
at the nape two-thirds its own length. Mouth chevron-formed, with a
tubercle at the extremity of the lower jaw: lips thin. Some
extremely minute teeth in the jaws, but none on the palate or
tongue. Suborbital obliquely truncated at the posterior angle, but
not dilated towards the extremity; the lower or anterior margin
straight, and scarcely if at all denticulated: the maxillary
slender, not longer than the suborbital, and concealed beneath it
when the mouth is closed. The eye has an adipose veil covering a
large portion of the iris: diameter of the orbit one-fourth the
length of the head: distance from the eye to the end of the snout,
equalling only three-fourths of the diameter. Orifices of the
nostrils widely separate. Number of scales in a longitudinal row
about thirty-five; perhaps one or two more: in the depth about
twelve. Fourth dorsal spine very weak. A large triangular scale
above the pectorals; the same also above the ventrals; this last,
which is the longer of the two, equalling one-fourth the length of
the fin.

D. 4—1/8; A. 3/8; C. 14, &c. P. 16; V. 1/5.
Length 11 inches 3 lines.

COLOUR.—“Back coloured like Labrador felspar: iris coppery.”—D. The
dried specimen shows traces of about twelve longitudinal lines
similar to those of many other species.

_A second specimen_ exactly resembles the above, except in being
smaller, measuring barely eight inches, and in shewing rather more
trace of denticulations on the suborbital.

Habitat, Bahia Blanca and Monte Video.

This species, which has the general characters of the _M. Cephalus_ of the European seas, is probably the _M. liza_ of Cuvier and Valenciennes; but the specimens are in a bad state of preservation, and some of the characters cannot be accurately ascertained. The depth of the body appears to have been rather greater than what is mentioned in the “Histoire des Poissons:” there is also some appearance of small scales on the second dorsal and anal, which, according to Cuvier and Valenciennes, is the distinguishing characteristic of their next species, the _M. curema_; but it will not agree with this last in its other details.

The larger of the above specimens was taken at Bahia Blanca, where Mr. Darwin’s notes state that it is plentiful; the smaller one at Monte Video.

2. MUGIL ——?

Mr. Darwin’s collection contains a second species of this genus from the Keeling Islands, which does not appear to be identical with any of those described by Cuvier and Valenciennes; but as there is but one specimen, in a very bad state of preservation, and the species inhabiting the Indian Ocean are very numerous, as well as extremely similar to each other, I refrain from describing and naming it as certainly new. I shall therefore merely point out some of its leading characters, so far as they can be ascertained; in the hope that they may prove of use in leading others to identify it who may visit the above Islands hereafter.

Form and appearance of the mouth similar to that of the _M. labeo_ of
the Mediterranean. Lips fleshy, and very much developed, with the
borders fringed; the lower one partially reflexed. Apparently no trace
of teeth anywhere. Suborbital with a shallow notch on its anterior
margin, obliquely truncated at its posterior angle, and obsoletely
denticulated. Maxillary slender and slightly bent, nearly concealed
beneath the suborbital, but showing a little beneath it, from its
being a trifle longer. The head is a little less than one-fifth of the
entire length: the snout short, and rather obtuse. Longitudinal
diameter of the eye contained three and a half times in the length of
the head: no appearance of any adipose veil. Orifices of the nostril
approximating. The depth of the body cannot be accurately ascertained,
but it appears to have been about one-fifth of the entire length. The
commencement of the anal is but very little in advance of that of the
second dorsal; both fins appear to have been covered with small
scales. Pectorals not quite so long as the head: apparently no
elongated scale above them: one, however, above the ventrals, half the
length of those fins. The fin-ray formula is as follows:—

D. 4—1/8; A. 3/9; C. 14; P. 16; V. 1/5.

The length of this fish is eight inches.

DAJAUS DIEMENSIS. _Richards._

Dajaus Diemensis, _Richards._ in Proceed. of Zool. Soc. 1840, p. 25.