DENTALIUM. 455 



seated fissure, evidences an essential distinction. We have 

 compared the two specimens which belonged to Turton, with 

 a perfectly fresh individual, in our own cabinet (the locality is 

 unknown to us) ; and, although the finely tapering posterior ter- 

 mination is uninjured, there is not the slightest appearance of 

 any slit. This species is slender, semi-transparent, moderately 

 arcuated, and of a pure white (stained, however, in one of the 

 Turtonian examples, with pale red at the narrower extremity). 

 It very slowly enlarges from the middle anteriorwards, so that 

 the mouth is not at all dilated ; behind it tapers to a very fine 

 point. Very numerous raised longitudinal lines, that are scarcely 

 equal in breadth to their interstices, occupy about one-third of 

 the shell at its lustreless hinder extremity ; the surface then 

 becomes highly polished and smooth ; but exhibits several obso- 

 lete rings of growth, which prevent it from being quite level. 

 The length of our own largest example was nearly one inch and 

 a quarter ; its breadth at the larger orifice barely exceeded the 

 tenth of an inch. 



An exotic shell, said by Turton to have been taken in Dublin 

 Bay. The D. semipolitum of Broderip and Sowerby {Zoolog. 

 Journ. vol. iv. p. 369,) may possibly prove identical, as the only 

 p>art of the very brief description which does not correctly apply, is 

 the statement, that the stria? occupy one half of the shell. 



D. octangulatum, Donovan. 



Dentalium octangulatum, Donov. British Shells, vol. v. pi. 1 62. — Brit. Marine 



Conch, p. 2 (part only). — Brown, Illust. Conch. 



G. B. p. 117, pi. 56, f. 2. 



„ octogonum, Lam. (ed. Desh.) Anira. s. Vert. vol. v. p. 591, (var.). — 



Desh. Monog. Dent. p. 32 (pi. 2, f. 5, 6!); Encycl. 



Meth. Vers, vol. ii. pt. 2, p. 74. — Sowerby, Zool. Journ 



vol. iv. p. 181. — Sowerby, Conch. Man. f. 2. — Deles. 



Rec. Coq. pi. 1, f. 1.— Chenu, 111. Conch. Dental, pi. 1, 



f. 22. 



„ striat/dum, Turt. Conch. Diction, p. 38 (part only).— Mont. Test. 



Brit. Suppl. p. 155. 

 „ aprinum, Mawe, (not authors) Linn. Syst. Conch, pi. 33, f. 1 . 



An exotic species, said to be Chinese (?); introduced by Dono- 

 van as taken on the sands of Cornwall. The diagnosis of striatu- 



