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. 



J. Mesites maculatus. Jen. 



Plate XXII. Fig. 4. 

 M. viridescenti-fuscus ; dorso et lateribus maculis crebris, hie et illic confluentibus, 

 nigris ; ventre niveo ; pinnarum radiis nigro-punctatis. 



B. 6 ; D. 10 ; A. 16; C. 16, &c. ; P. 12 ; V. 7. 

 Long. 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. 



