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Show 372 MESSRS. MACDONALD AND BARRON [May 28, the snout blunt and rounded ; the nostril crescentic and very near the end of the snout; the eye small, without a nictitating membrane, having a round pupil and bronzed silver iris. The mouth convex, with a wide gape and long corner fold. The seven gill-slits all in front of the pectoral fin, of large size, decreasing posteriorly and extending low on the throat. The single dorsal fin situate intermediate between the anal and ventral fins ; the pectoral fins large and broad; the upper lobe of the tail very long, and notched on the underside near its extremity, the lower lobe very short, with a small lobule. No tail-pits. The colour of the upper parts of the skin in the male fish brownish grey, with a few white spots interspersed among numerous smaller black ones, sprinkled over the back and sides; the belly clouded white. This description applies also to the female, except that on it no white spots were observed. The examination of the preparations of dried skin from specimens of each sex shows that little need be added to Mr. Rayner's description, save that the skin of the male, when viewed with the light falling along it lengthwise, is plainly seen to be marked with numerous transverse zebra-like stripes, and it is also curious to observe that the sites of the white spots, on the skin of the male, are marked by a fewness of scales; and this character is in direct proportion to the intensity of the spots, so that it is not improbable they may be the result of disease. Important and distinctive dental features are revealed by the examination of the jaws of the two sexes of this species, and which, so far as our investigations have gone, have been hitherto unnoticed, though, when the two are seen together, the differences are at once plain and striking. This can only be accounted for on the supposition that the two sexes have not been sufficiently compared together, which is likely from the apparent paucity of the specimens, as Muller and Henle only mention one in Leyden and one in Paris, and the British-Museum Catalogue only includes two stuffed specimens. The figure given in Muller and Henle's work, plate 32, is that of a female, and the teeth there delineated give an exceedingly faint notion of the characteristics of either sex ; the teeth of H. cinereus, represented on plate 35, more nearly resemble those of the female of this species. Teeth of male :-Upper jaw, three central rather crowded symmetrical teeth, somewhat quadrate at the base, with a strong and sharp fang arising straight from the centre of each, the outer ones having a small denticle on one or both sides, absent in the central tooth. The side teeth are similar in shape, but broader at the base, with the central fang directed towards the corner of the jaw, and a well-developed laterally directed denticle on each side; the teeth also, as they recede from the centre, have other little denticles appearing nearer the base, and these amount to three on each border of the last fanged tooth. Lower jaw-one central symmetrical tooth, flat and nearly quadrate at the base, and crowned with six graduated denticles, diverging laterally, three on each side, the side teeth larger, flat, subquadrate, and vertically grooved below, crowned with graduated denticles, asymme- |