40 DENTALIUM. 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 striae, and the 

 want of the contraction at one end and the knob at the 

 other, sufficiently distinguish it from D. imperforatum. v. m. 



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 

 o( what we consider to be the true D. Entalis, the aperture 

 at the pointed extremity is oval, with a small slit down the 

 back 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,}). 497- 



Shell curved, of equal diameter at both ends, glossy 

 white, quite smooth ; one end open, the other closed 

 rounded and slightly margined : length hardly a line. 



On the Devonshire coast, and North Britain : rare. v. m.. 



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-sheH. 

 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 j the smaller end closed, truncate, 

 and furnished with a small round protuberance : color 

 rusty-brown, paler towards the smaller end : length above 

 the eighth of an inch. 



It differs from the last, in being more curved., in its COT 

 lor and strong ribs, and in having no contraction at the top. 



On Milton sands ; very rare. 



BONAX, 



