DENTAL IUM'. TOOTH-SHELL. 39 
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 lend, 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. 
Eg. 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 
line 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 nqt 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, much longer in proportion to the breadth, and 
I are faintly but evidently striate on the lower part only. 
. 
8 . Dentalium imperforatum. Imperforated Tooth-shell. 
Walker , f. 15. 
Shell slender, slightly curved, whitish, transversely stri¬ 
ate j the larger end a little contracted at the margin: the 
smaller end clqsed, 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- 
s ate longitudinally, open at the larger end, with the oppo- 
s site end closed and obtuse: length an inch 5 diameter at the 
1 open end the eighth of an inch. 
f e? Two 
