_Form._—The body is moderately compressed, its greatest thickness being somewhat more than one half of its depth. Its profile is oblong, tapering more toward the tail, which is nearly cylindrical: its greatest depth is at the ventrals, and rather exceeds one-fourth of the total length, caudal included.
The head constitutes two-sevenths of the total length, and its height, at the eye, is equal to one-half its length from the tip of the snout to the point of the gill-cover. The forehead is flat, but appears depressed, owing to the convexity of the nape. The snout is a little convex. The orbits are lateral, distant more than one of their own diameters from the tip of the snout, and more than two diameters from the point of the gill-cover. The jaws are equal. The mouth descends on it runs backward, its posterior angle being under the centre of the orbit.
_Teeth._—The intermaxillaries, lower-jaw, knob of the vomer, and edge of the palate-bones, are covered with very small, straight or slightly-curved, densely-crowded teeth (_en velours._) The vault of the palate, posterior part of the vomer, and the pointed tongue, are smooth.
_Gill-covers._—The preoperculum is narrow; its upper limb rising vertically forms a right-angle with the lower one; and its edge is armed with small spinous teeth, those on the lower limb being directed forward. The bony operculum terminates in a narrow sub-spinous point, beneath which there are three denticulations, with grooves running backward from them. An acute-pointed membranous flap prolonged from the margin of the suboperculum conceals these parts in the recent fish. The edge of the interoperculum and posterior part of the suboperculum are minutely denticulated. The edges of the humeral bones are slightly grooved and denticulated, the denticulations being more obvious in some individuals than in others.
_Scales._—There are sixty scales on the lateral line, and twenty-two in a vertical row between the first dorsal and centre of the belly. The scales are rather small, their bases truncated and furrowed to near the middle (_striées en éventail_) by six grooves corresponding to eight minute lobes of the margin. A narrow border of the outer rounded edge is very minutely streaked, producing teeth on the margin, visible under a lens. The length and breadth of a scale, taken from the side, are about equal, being two and a half lines. A linear inch measured on the sides or belly, longitudinally, contains twelve scales, the scales on the belly having, however, less vertical breadth. On the back an inch includes seventeen or eighteen. The asperity of the scales is perceptible to the finger, when it is drawn over them from the tail toward the head. The lateral-line is thrice as near to the back as to the belly, and is slightly arched till it passes the dorsal and anal fins, when it runs straight through the middle of the tail. It is marked on each scale by a tubular elevation, which is divided irregularly by an oblique depression.