FISH. 119 
Mr. Darwin’s collection contains no less than three species of this new genus, 
differing but slightly from each other. Two are from the most southern parts of 
South America, the third from New Zealand. 
1. Mesires MACULATUS. Jen. 
Puate XXII. Fig. 4. 
M. viridescenti-fuscus; dorso et lateribus maculis crebris, hic et illic confluentibus, 
nigris ; ventre niveo ; pinnarum radits nigro-punctatis. 
Bl62D 10:5 Aig- iG. 16; &és- POD Vice 
Lone. unc. 2. lin. 8. 
Form.—Slender and very much elongated. Body anteriorly subcylindrical, compressed behind. 
Greatest depth not more than one-eighth of the entire length: thickness about three-fourths of 
the depth. Head rather depressed, about one-sixth of the entire length. Snout short and 
rounded ; mouth at the extremity; the gape moderate, not quite reaching to beneath the an- 
terior angle of the eye. Lower jaw ascending a little to meet the upper, and, when the mouth 
is open, appearing rather the longest. Intermaxillary 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. Teeth 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 longi- 
tudinal 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 of minuter ones, down the 
middle of the vomer; none, however, on the palatines or pharyngeans. Eyes rather large, 
their diameter contained about three and a half times in the length of the head, distant 
scarcely one diameter from the end of the snout. The nostrils appear to consist of only a 
single aperture in front of the eye, in the neighbourhood of which, and also above the eye, are 
several large pores. The opercle and subopercle taken together approach to an oblong form, 
the posterior margin being straight and nearly vertical: the subopercle is not much developed, 
nor very distinct. Gill-opening very large, the membrane thick, with six rays, deeply notched 
beneath, and not fastened down. The whole skin is perfectly smooth and naked, invested 
with mucosity. No 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. 
The dorsal and anal are opposite to each other, and both placed very far back, almost at 
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 length; but the anal being longer 
than the dorsal, it extends nearer the caudal. The form of these fins is much as in the genus 
Cobitis. The 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. The vent is just before the anal. The ventrals 
arise from about the middle of the entire length, the distance from their insertion to the com- 
mencement of the anal being twice their own length. The 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. 
