32 



The three above-mentioned specimens supply the following information regarding the 

 structural characteristics of the species:— 



The fish is small, robust, in general shape fusiform, reaching a length of 59 mm. with a depth 

 in advance of the dorsal fin of 15 mm. The length of the head, including the opercular apparatus, 

 is a little less than one-fourth of the total length. The snout is rounded and projects beyond 

 the lower jaw. The orbit is large and placed far forward. The bones of the head are ornamented 

 with well defined, short vermicular ridges, and tubercles, the former being generally in the 

 direction of the length of the bone. The mandibular suspensorium is nearly vertical, and thus 

 differs from that of Rhadinichthys, which is obhque. The dorsal and ventral fins are triangular 

 and of fair size, the former slightly larger than the latter. In the ventral fin the base is about 

 equal to the anterior and posterior margin. In the dorsal fin the base is proportionately larger 

 and exceeds the posterior height. The dermal rays are delicate and seern to bifurcate distally; 

 they are articulated, with the exception of the principal ones of the pectoral fins, which appar- 

 ently are not articulated, at least proximally. Fulcra occur on all the fins. The anal fin is 

 opposite the dorsal, and the ventral pair is slightly closer to the anal than to the pectorals. The 

 caudal fin is heterocercal and deeply forked, the body prolongation in the upper lobe tapering 

 gradually. The scales are rather coarsely sculptured. The exposed surface of those on the 

 flank, anteriorly, plate XI, fig. 4, is slightly higher than broad, but a little farther back the height 

 and breadth are about equal. Their sculpture consists of two or three delicate but distinct well- 

 defined ridges in the lower half of the surface, parallel to the lower margin, with three to five 

 short, prominent ridges in the upper half of the scale; these latter are directed obliquely back- 

 ward and downward in a somewhat divergent manner, from a slightly raised but ill-defined area 

 confined to the upper, anterior portion of the scale. These short ridges do not, as a rule, reach the 

 posterior margin, and often stop far short of it. The posterior edges of the flank scales are coarse- 

 ly toothed, three or four being the usual number of the denticulations. In passing backward 

 the surface ridges of the scales are reduced in number, as are also the denticulations of the pos- 

 terior margins, plate XI, fig. 6, until posteriorly, in the small diamond-shaped scales of the 

 caudal body prolongation, all trace of sculpture is lost and the surface of each scale is smooth. 

 Enlarged, imbricating scales, plate XI, fig. 7, extend along the median fine of the back, in a 

 single row, from the head to the commencement of the dorsal fin, and from behind this fin to 

 the caudal one, on which they are continued as large fulcra-like modifications, decreasing in size 

 posteriorly. Their sculpture consists of well-marked longitudinal ridges, conforming, in a 

 general way, to the curvature of the lateral margins. On the ventral surface a row of similarly 

 enlarged and ornamented scales occurs between the ventral and anal fins, and between the latter 

 and the base of the caudal, where it gives place to small fulcra on the lower anterior margin 

 of the tail. Similarly enlarged scales appear to be present in advance of the ventral fins as far 

 forward as the pectoral pair, but they are imperfectly seen and nothing definite can be said 

 regarding them. The enlarged dorsal scales are ovoid in outline, broadly rounded in front, 

 and slightly narrower behind. They decrease in size toward the head, the largest ones occurring 

 in advance of the dorsal fin. The ventral ridge scales nearest to the base of the tail are parti- 

 cularly conspicuous. Of the flank scales the largest are those of the lateral fine. Toward the 

 back and belly the flank scales decrease in size, those of three or four rows on either side of the 

 median dorsal row being decidedly smaller, plate XI, fig. 5, with a more sloping posterior border. 



