40 0ENTALIUM. TOOTH-SHELL 
Two specimens only of this species have as yet occurred 
to us, both of them collected on the Calves Islands, in the 
•west of Ireland. The size, the longitudinal strife, and the 
want of the contraction at one. end and the knob at the 
other, sufficiently distinguish it from 1). imperforatnra. tr.». i 
The difficulty of procuring living or very perfect speci¬ 
mens of the several species of this family, has no doubt 
contributed much to their obscurity. In all our specimens 
of what we consider to he the true D. Entails, the aperture , 
at the pointed extremity is oval, with a small slit down the j 
hack or convex side; and in our most perfect specimen, . 
just below the orifice at the smaller end, is a circular 
groove, as if it had been indented by a tight ligature. 
10. Dentalium glabrum. Smooth Tooth-shell. 
Montagu , p. 497- 
Shell curved, of equal diameter at both ends, glossy 
white, quite smooth ‘ 7 one end open, the other closed 
rounded and slightly margined : length hardly a line. 
On the Devonshire coast, and North Britain : rare, v.vl 
11. Dentalium Gadus. Hakes Tooth-shell. 
Montagu> pi. 14. f. 7- 
Shell slender, tapering to a fine point, slightly curved,' 
open at both ends, narrowed at the larger end beneath 
which it is inflated: color white, glossy, and quite smooth: 
length about three eighths of an inch. 
In the ocean, brought up with the sounding lead. v. v. 
12. Dentalium Trachea. Windpipe Tooth-shell. 
Montagu , pi. 14. f. 10. 
Shell a little tapering, curved, marked with regular 
strong rounded transverse ribs or annulations, not con¬ 
tracted at the larger end ; the smaller end closed, truncate, | 
and furnished with a small round protuberance: color j 
rusty-brown, paler towards the smaller end: length abore 
the eighth of an Inch 
It differs from the last, in being more curved, in its co¬ 
lor and strong ribs, and in having no contraction at the top. 
On Milton sands : very rare. 
DONAX. 
