Art. XXIII.—A New Species of Shark.
[Read before the Philosophical Institute of Canterbury, 1st December, 1920; received by Editor, 31st December, 1920; issued separately, 20th July, 1921.]
On the 12th June, 1920, Mr. C. W. Sherwood, of New Brighton, presented to the Canterbury Museum a small shark which he had found on the New Brighton beach. It is considered to be a new species of Scymnodon, a genus of small sharks living in deep water, and. is named after its discoverer.
Scymnodon Bocage and Capello, 1864.
Scymnodon Bocage and Capello, Proc. Zool. Soc., 1864, p. 263. Zameus Jordan and Fowler, Proc. U.S. Nat. Mus., vol. 26, p. 633, 1903. Scymnodon Tate Regan, Ann. Mag. Nat. Hist., ser. 8, vol. 2, p. 48, 1908.
Dermal denticles (fig. 1) pedunculate, with 3 parallel keels, each ending in a point, the central keel being the longest.
Distance from mouth to snout less than half the distance between snout and first gill-opening (proportion 9: 23). Nostrils oblique, distance between them three-fifths of preoral length of snout. Length of anterior labial fold about equal to its distance from the symphysis.
Anterior dorsal fin shorter than the 2nd, length of its base three-tenths of the distance between it and the 2nd dorsal. Anterior end of 1st dorsal distant from the snout by nearly half the total length of the fish. Posterior extremity of pectorals falls short of the anterior end of the 1st dorsal by more than its own length. Posterior extremity of claspers reaching to vertical from half-way along free posterior border of 2nd dorsal.
Total length, 803 mm. Colour dark brown, with two submedian lighter areas extending from below the gill-openings to the ventrals. Angles of gill-openings tipped with dirty-white, posterior angle and posterior border of pectorals with narrow dirty-white margin. The spines of the dorsal fins are scarcely discernible rudiments embedded in the fin.
This species differs from Scymnodon squamuiosus (Gunther)* in its shorter snout, the wider space between the nostrils, the more posterior position of the 1st dorsal, and the brown colour A median dorsal silvery blaze extends from level with the spiracles to level with the hinder end of the base of the pectorals; it is caused through the denticles of the area being slightly raised and without the brown pigmentation of the other denticles, and is possibly not a natural condition.
Type in the Canterbury Museum.
The specimen is a male; its claspers are 1.8 in. long, and bear subterminally a curved sharp claw 0.6 in. long.
[Footnote] *Centrophorus squamulosus Gunther, “Challenger” Deep-sea Fishes, p. 5, pl. ii, fig. B, 1887.