CANOBIUS POLITUS. 179 



The shape is fusiform, the dorsal and ventral margins being pretty evenly and 

 elegantly curved. The length of the head is contained approximately twice in the 

 distance between the tip of the snout and the commencement of the dorsal tin and tin ice 

 up to the origin of the caudal. 



The cranial roof-bones are ornamented with comparatively coarse ridges, frequently, 

 and in some specimens more than others, becoming broken up into round or elongated 

 tubercles. The snout forms a rounded prominence over the mouth, and behind it is 

 placed the orbit, of considerable size. The suspensorium is only very slightly oblique 

 in its direction; the operculum and suboperculum are nearly of equal size, and when 

 their external ornament is seen it is more or less of a striated character. The maxilla 

 apparently resembles that of the preceding species in form, having a short, broad 

 posterior portion passing into a narrow tapering process which runs forwards below the 

 orbit. The mandible is short, stout, and straight, and ornamented with longitudinal 

 and oblique ridges, which are somewhat finer than those on most of the other bones of 

 the head; on its margin several minute sharp conical teeth may be distinguished. 



The scales (figs. 15, 16) are of moderate size, largest and least oblique on the front 

 of the flank, and diminishing in size posteriorly and towards the dorsal and ventral 

 margins. Along the belly, between the pectoral and anal fins, the scales are also low 

 and narrow ; but those along the middle line of the back are not specially large or 

 prominent, excepting a few just in front of the dorsal fin. Over nearly the whole of 

 the body the scales are almost smooth on their exposed surfaces — only on the back 

 near the middle line do we observe a few grooved striations, while on the flank- 

 scales of some specimens we also observe some faint indications of obsolete ridges passing 

 with some slight obliquity from before backwards and downwards. The posterior 

 margins of the scales of the side of the body are, as far back as the tail-pedicle, marked 

 with tolerably well-marked denticulations. 



In the type specimen (fig. 12) a small pectoral fin is visible, but unfortunately its 

 state of preservation is not such as to render a minute description warrantable : remains 

 of the ventral are also seen midway between the pectoral and anal. The dorsal fin 

 commences only very sliijhtlv in front of the anal; both are of the usual acuminate 

 form, with tolerably delicate rays, which are smooth, distantly articulated and dichoto- 

 mising towards their terminations; well-developed fulcra are seen along their anterior 

 margins. The caudal fin is well seen in figs. 13 and 14 ; it is of the usual heterocercal 

 deeply divided contour, and its rays are similar in character to those of the dorsal and 

 anal. 



Observations. — This species is evidently very closely allied to the preceding, from 

 which it may, however, at once be distinguished by the smoothness of its scales and by 

 the greater coarseness of the ornament on the cranial roof-bones, which, moreover, 

 always partakes more or less cf a ridged character; the suspensorium seems also more 

 nearly vertical in its direction. 

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