REPORT ON FOSSIL FISHES. D9 
Canobius politus, sp. nov. Traquair. 
Pl. V. figs. 14-16. 
Description.—The specimens of this form, none of which have the caudal 
fin perfectly preserved, represent a small fish of from 24 to 3 inches in length, 
and of somewhat deeply fusiform proportions, the dorsal and ventral margins 
being pretty evenly and elegantly curved. The greatest depth of the body, 
midway between the head and the dorsal fin, is # inch to 1 inch; the length of 
the head is contained approximately twice in the distance between the tip of 
the snout and the commencement of the dorsal fin, and thrice as far as the 
commencement 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 
rounded or elongated tubercles. The snout forms a rounded prominence over 
the mouth, and behind it is placed the orbit, of considerable size. The suspen- 
sorium is only very slightly oblique in its direction; the operculum and inter- 
operculum are nearly of equal size, and where their external ornament is seen 
it consists of more or less concentric ridges. The shape of the preeoperculum 
cannot be made out. 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 forward 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 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 nearly absolutely smooth on 
their exposed surfaces, only on the back, near the middle line, do we observe a 
few grooved striations; and the flank scales of some specimens show some faint 
indications of obsolete ridges, passing with a slight obliquity from before back- 
wards 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 one specimen 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 slightly in front of the anal; both are of 
the usual acuminate form, with tolerably delicate rays, which are smooth, 
