T
II
F o r m .— Still more slender and elongated than the last species. G reatest depth scarcely one-ninth
of the entire length ; head one-sixth. Dorsal and ventral lines veiy little curved. General
characters of the head, snont and m outh, as in the A . microlepidota, but the jaw s more protractile.
A row of m inute velutine teeth in each jaw most developed above. Eyes moderately
large ; their diameter nearly one-third the length o f the h ead ; the space between them ju st
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 ot jagged, according to the spot whence tak en : 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. B readth of the silver band one-fourth the depth of the body.
COLOOH.— “ 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 baud 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 otiier respects they are similar.
Mr. Darwin's notes state that this species was taken in the month of
September, in 39° S. Lat., 01° 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.
F a m i l y .— M UG ILIDÆ .
1. M u g i l LIZA. C u v .e t V a l. I
Mugil liza, Cuv. et Val. Hist, des Poiss. tom. xi. p. 61.
F o r m .—Elongated : the depth contained about five and a half times in the entire lengtli : the head
FISH. 81
exactly five tim es: height o f the head a t the nape two-thirds its own length. M outh chevron-
formed, with a tubercle a t the extremity of the lower ja w : lips thin. Some extremely minute teeth
in the jaw s, but none on the palate or tongue. Suborbital obliquely truncated a t the posterior
angle, but not dilated towards the extrem ity; the lower or anterior margin straight, and scarcely
if at all denticulated : the m axillary 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 o f the iris :
diameter of the orbit one-fourth the length of the h e a d : distance from the eye to the end of the
snout, equalling only three-fourths of the diameter. Orifices of the nostrils widely separate.
Num ber of scales in a longitudinal row about thirty-five; perhaps one or two m ore: 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 I I inches 3 lines.
C o l o u r .— “ B ack 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.
H abitat, B ahia B lanca and Monte Video.
This species, which has the general characters of the 31. Cephalus of the
European seas, is probably the 31. Liza of Cuvier and V alenciennes; 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;” tliere 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 31. ciirema; 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 . M u g i l ?
Mr. Darwin’s collection contains a second species of this genus from the
Keeling Islands, which does not appear to be identical witii 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.