G e n u s— MESITES. Jen.
Corpus elongatnm, gracile, antice subcylindricum, postice compressum, nudum, squamis
nullis. C aput depressum. R o strum breve, obtusum : os terminale, rictu modico.
M a xillie debiles ; superior margine ex ossibus interm axillaribus omnino form ato,
m axillaribus retroductis et a labio p artim celatis. D enies m inuti, acuti, in m axillá
utraque uniseriati ; in lingua et vomere hiseriati ,■ in ossibus palatinis et pharyngalibus
nulli. A pertura hranchialis amplissima, membrand sex-radiatd, suhter
gulam profundé emarginata, haud isthm o annexd. P in n a dorsalis et analis valde
retropositcs, opposite. P in n a pectorales et ventrales pai-vce. P in n a caudalis
leviter emarginata.
There can be no doubt, I imagine, as to this being an entirely new form,
and a very interesting one, from the circumstance of its being at the
extreme end of the family to which it belongs, and its very much departing from
the usual cliaracters of that family. I have referred it to the Cyprinidce, taking
that group in the enlarged view in which Cuvier accepts it ; though by those who
divide it into subfamilies it would probably be associated with the C obitida, or
made to constitute a distinct one by itself. It agrees with the Cyprinidce in
general in the form of its mouth, in the upper jaw having its margin entirely
formed by the intermaxillary, the maxillary being present, but placed behind and
partly concealed in the thickness of the lip, and in the want of an adipose ; but
it altogether departs from that family in the entire want of scales, of which there
is not even a vestige in the dried skin, and in which respect it would seem to
shew an affinity to the S ilu rid a . Yet it has none of the other characters of the
family just mentioned. On the other hand, in the backward position of the
dorsal and anal fins, which are opposite to each other, it agrees with the Esocidce.
The pharyngeal bones are unarmed, but this deficiency is made up for by the
strong curved teeth on the tongue, independently of the minuter ones in the jaws.
The intestine is extremely short and quite straight, measuring only fourteen
lines in length from the pylorus to the anus, in a specimen two inches and a half
long. The stomach is of an oval form, of considerable capacity, very membranaceous,
with the cardiac and pyloric openings near together at the upper
extremity, from the latter of which the intestine is immediately reflexed to pass
off to the anus. In the specimen dissected, the stomach was much distended by
a nearly perfect individual of the genus Colymhetes, which appeared to have been
recently swallowed, and was scarcely at all altered. There are no coecal appendages.
The air-bladder is of an elongated oval form, and of considerable development.
Mr. D arw in’s collection contains no less than three species of this new genus,
differing but slightly from each other. Two are from the m ost southern parts of
South A m erica, the third from New Zealand.
1. M e s it e s m a c u l a t u s . Jen.
P l a t e X X II. Fig. 4 .
M . viridescentifuscus; dorso et lateribus maculis crebris, hie et lU ic conjluentibus,
nigris ; ventre niveo ; pinnarum radiis nigro-punctatis.
B . G; D . 10; A. 16; C. 16, & c.; P . 12; V. 7.
L o n g . u n c . 2 . lin . 8.
F0RM.-SlGnder and very much elongated. Body anteriorly subcylindrlcal, compresced behind.
G reatest depth not more than one-eighth of the entire length ; thickness about three-fourths of
the depth. H ead rather depressed, about one-sixth of the entire length. Snout short and
rounded ; m outh at the extrem ity; the gape moderate, not quite reaching to beneath the anterior
angle of the eye. L ow er jaw ascending a little to meet the upper, and, when the mouth
is open, appearing rather the longest. Interm axillary fixed, forming the entire margin of the
upper jaw, the maxillary being behind it, and, though of nearly equal development, not
very distinct; both bones slender. T eeth small, but sharp-pointed, rather widely apart,
arranged in a single row along the edge of the intermaxillary, and in the lower jaw ; the
series above consists of about eighteen, that below of about twenty-one ; also a double longitudinal
row on the tongue, each row containing five or six teeth, the anterior ones curved,
and larger than any of those in the jaws ; a similar double row, but ot m innter ones, down the
middle of the vom er; none, however, on the palatines or pharyngeans. Eyes rather large,
their diam eter contained about three and a h alf times in the length of the head, distant
scarcely one diameter from the end of the snout. T he nostrils appear to consist of only a
single aperture in front of the eye, in the neighbourhood of which, and also above tho eye, are
several large pores. T he opercle and subopercle taken together approach to an oblong form,
the posterior margin being straight and neatly v ertical; the snboperclc is not much developed,
nor very distinct. Gill-opening very large, the membrane thick, with six rays, deeply notched
beneatli, and not fastened down. T he whole skin is perfectly smooth and naked, invested
with mucosity. N o appearance of any lateral line, unless a fine dark streak be so called, passing
along the middle of the sides, and dividing them into two equal parts,
Tho dorsal and anal are opposite to each other, and both placed very far back, almost ot
the extremity of the body. They commence In nearly the same vertical line, a very little
anterior to the commencement of the last third of the entire len g th ; but the anal being longer
than the dorsal, it extends nearer the caudal. T he form of these fins is much as m the genus
Cobitis. T he dorsal has the first three rays simple, the rest branched; the anal also has the
first three simple, the first very short. Caudal about one-eighth of the entire length, with a
shallow notch, the principal rays branched. T he vent is just before the anal. T he ventrals
arise from about the middle o f the entire length, the distance from their insertion to the com m
encement of the anal being twice their own length. T he pectorals are small, and rather
narrow, equalling about two-thirds the length of the head or hardly so much ; they are attached
low down, but not quite so low as in the genus Cobitis.