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 ex- 

 tending 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 descrip- 

 tion, save that the skin of the male, when viewed with the light 

 falling along it lengthwise, is plainly seen to be marked with nu- 

 merous 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 supposi- 

 tion 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 IMiiller 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 symme- 

 trical 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 late- 

 rally 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 ver- 

 tically grooved below, crowned with graduated denticles, asymme- 



