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.