the upper part, marked below with numerous longitudi- 

 nal striae which are very distinct at the point, but grow 

 fainter towards the middle, and at length totally disap- 

 pear ; clear white with a pale rufous tinge at the 

 smaller end. 1,1. Breadth at larger end, 0,048. Dublin 

 Bay. 



D. IMPERFORATUM. Walker, f. 15. Mont. p. 496. 

 D. p. 1068. Adams t. 14. /. 8 Turt. D. p. 39. 

 Lin. T. 8. p. 238 ORTHOCERA. T. P.p. 237. Slender, 

 slightly curved, whitish, transversely striated, the 

 larger end a little contracted at the margin, the smaller 

 end closed and furnished with a small round protube- 

 rance. $. Kent and Cornwall. 



D. CLAUSUM. Turt. D. p. 39. Slender, slightly 

 tapering, nearly straight, semi-transparent, horn colored 

 or yellowish white, irregularly striated longitudinally, 

 open at the larger end, with the opposite end closed and 

 obtuse. 1. at larger end ^. Calves Island, W. 

 Ireland. 



D. GLABRUM. Mont. p. 497. Turt. D. p. 40. 

 Lin. T. S.p. 239. D. MINUTUM. D. p. 1068. An 

 Lin 1264 ? CAECUM. G. Flem, Edin. Ene. 7. p. 67. t. 

 204. /. 7. ORTHOCERA. G. F. p. 237. Cylindric, 

 arcuated, smooth, glossy, white, perfectly smooth ; 

 aperture orbicular,, the other end closed, rounded, sub- 

 marginated. 0,0833... 0,0 167. Not uncommon at 

 Biddeford Bay and Barnstaple, Devon. 



