DENTALIUM. TOOTH-SHELL. S& 



very obtuse, not truncate, but rounded, with an oval per- 

 foration : length an inch; breadth at the larger, extremity 

 two tenths of an inch ; at the smaller end one eighth. 



The outline of this shell very much resembles that of 

 the D.-labiatum.; but its polished surface, rounded termi- 

 nation at the smaller end, and the want of the projecting 

 lip, strongly mark its distinction. We believe it to be very 

 rare, as we have yet been able to obtain two living speci- 

 mens only, both of them dredged up at Torbay. v. v. 



7- Dentalium semistriatum. Semistriated Tooth-shell. 

 Fig. 68. 



Shell very slender, tapering to a very fine point, glossy, 

 transparent, a little curved, open at both ends, quite smooth 

 on the upper part, the 'lower part marked with numerous 

 fine longitudinal striae, which are very distinct at the point, 

 but grow fainter towards the middle and at length totally 

 disappear : color clear white, with a pale rufous tinge at the 

 smaller end : length more than an inch ; diameter at the 

 larger end not the twentieth part. 



Two specimens of this new and very delicate species 

 were found near the Pigeon-house, in Dublin bay. They 

 are much more transparent than the last, much thinner in 

 substance, mueh longer in proportion to the breadth, and 

 are faintly but evidently striate on the lower part only. 

 v. m. 



$. Dentalium imperfqratuia. Imperforated Tooth-shll. 



Walker, f r 15. 



Shell slender, slightly curved, whitish, transversely stri- 

 ate j the larger end a little contracted at the margin ; the 

 smaller end closed, and furnished with a small round pro- 

 tuberance : length the eighth of an inch. 



In Falmouth harbour : very rare. 



9. Dentalium clausum. Closed Tooth-shell. 



Shell slender, slightly tapering, nearly straight, semi- 

 transparent, horn -color or yellowish-white, irregularly stri- 

 ate longitudinally, open at the larger end, with the oppo- 

 site end closed and obtuse : length an inch ; diameter at the 

 open end the eighth of an inch. 



2 Two 



