F a m i ly — M Æ N IDÆ .
1. G e r r e s G u l a . C u v .e t V ol.?
Gerres Gula, Cue. et Val. Ilist. des Poiss. tom. vi. p. 349.
F orm.— G reatest depth one-fourth of the entire length. B ack but little elevated. Space between
the eyes flat, with a fovea in the middle, which is prolonged in a channel nearly to the extremity
of the snout. Length of the head exceeding its depth by one-fourth, and contained about three
times and three quarters in the entire length. So much of the maxillary as is visible is of an
oval form, its length being twice its breadth a t its posterior extremity. Suborbital with the
lower margin very indistinctly notched, and not denticulated. Eyes very large, their diameter
contained twice and three quarters in the length of the head. The two orifices of the nostrils
of nearly equal size. No denticulations on any of the pieces of the gill-cover. A narrow band
o f very minute velutine teeth in each jaw , those above hardly visible to the eye, but sensible to
the touch : none on the vomer, palatines, or tongue.
Dorsal with the first spine extremely short; the second has a small piece broken off at the
tip, but appears to have been about the same length as the third, which last equals two-thirds
of the depth of the body ; the fourth and fifth are a little shorter than the third ; the succeeding
ones gradually decreasing, as in the other species of this genus: all the spines are moderately
slender, the anterior ones slightly arcuate, with scarcely any appreciable difference in the degree
of stoutness in the first four. Anal with the first spine extremely short ; the second obviously
stouter than any of the dorsal spines, but much shorter, being only half the length of the second
dorsal spine, or one-third the depth of the body ; the third spine is a trifle longer than the
second, but much slenderer. C audal deeply forked ; the lobes worn at the tips in this specimen,
but their length, when perfect, probably about one-fourth, or somewhat less, of the entire length
of the fish. Pectorals narrow and pointed, a little shorter than the head, and contained four
and a h alf times in the entire length ; fifth ray longest. V entrals a little behind the pectorals,
and not more than two-thirds their length, or scarcely so much ; the spine a little shorter than
the soft rays, and of about the same degree of stoutness as the dorsal spines. Elongated scale
in the axillæ of the ventrals about three-fourths the length of the spine, of a narrow lanceolate
form, ending in a very fine point.
D. 9/10; A. 3/7; C. 17, &c. ; P . 14; V. 1/5.
Length 3 inc. 0 lines.
Colour.— N ot noticed in the recent state. In spirits, it appears of a uniform silvery, with the back
and upper part of the sides inclining to dusky olive: no bands or any particular m arkings:
fins pale.
Habitat, Rio de Janeiro.
The species of this genus are numerous, and extremely similar to each other.
Many of them appear to rest on characters taken simply from the relative lengths
and degrees of stoutness of the dorsal and anal spines. This renders it extremely
difficult to identify single specimens. Perhaps I am wrong in referring the one
described above to the G. Gula of Cuvier and Valenciennes; but it makes so
near an approach to that species, that I hardly dare characterize it as distinct.
It cannot be the G. Aprion of those authors, which is closely allied to the G. Gula,
and is found on the same coasts, since its teeth are so very much finer: the
caudal also is not scaled. It is small, but Cuvier and Valenciennes state that
none of their specimens of the G. Gula exceed five inches. Mr. Darwin took it
in a salt-water lake, Lagoa de Boacica, at Rio de Janeiro.
2. G e r r e s O y e n a . C xiv.et V al.?
Gerres Oyena, Cuv. et Val. Ilist. des Poiss. tom. vi. p. 355.
Smaris Oyena, Riippell, Atlas zu der Reise ira Nord. Afr. Zoologie; p. 11. tab. 3. fig. 2.
F o r m .— G reatest depth contained rather more than three and a half times in the entire length: the
dorsal curve very regular. Profile above the eyes a little concave. Length of the head exceeding
its depth. Maxillary as in the species last described. Suborbital with its lower margin distinctly
b u t not very deeply notched; not denticulated. Diameter of the eye less than one-third the length
of the head. Posterior orifice of the nostrils twice the size of the anterior one. No denticulations
on any part of the head or gill-cover. A narrow band o f velutine teeth in each jaw , of
about the same length and degree of fineness above and below ; but none on the palate or
tongue.
The dorsal commences in an exact vertical line with the insertion of the ventrals: the anterior
spines are a little arcu ate; the first, as in the other species of this genus, is extremely sh o rt;
the second and third in this specimen are broken a t their extremities so that their exact length
cannot be ascertained, but the portion of the second remaining (and of this spine apparently
only a very small piece is gone) nearly equals half the depth of the body; length of tlie fourth
spine which is perfect not quite equalling two-fifths o f the depth ; fifth, sixth, and seventh spines
gradually decreasing; eighth and ninth scarcely shorter than the seventh : the second spine
is much compressed, aud though obviously stronger than any of tliose which follow, not nearly
so stout as in many other species; its breadth is not more than one-twelfth of its length. Anal
commencing in a line witli the fourth soft ray of the d orsal; the second spine compressed
similarly to the second-dorsal spine, and of about the same degree of stoutness, but its length
one-third less, being ju st equal to one-third the depth of the body ; the third spine scarcely
shorter than the second, but much slenderer; the soft rays gradually decreasing from the first,
which is a little shorter than the third .spine, to the last but one, the last itself slightly prolonged