ACLis. 223 



dorsally occupies about three-fourths of the length ; if 

 examined ventrally, scarcely one-third ; the apex is mo- 

 derately pointed. The sculpture consists of extremely 

 numerous but not crowded, fine, and somewhat curved, 

 longitudinal costellae, whose broader intervals are crossed 

 by still finer close-set spiral strise, which latter likewise, 

 under the microscope, appear to be elevated. The base, 

 which is not compressed, but gradual in its slope, is 

 rounded, and in fresh individuals is not smooth, but ex- 

 hibits a continuation of the preceding sculpture, of which 

 the spiral lines are the more manifest : there is no perfora- 

 tion of the axis. The aperture, were it not for the interrup- 

 tion of the body, would be oval ; it occupies about one-fifth 

 of the entire length of the shell, and fully one half of the 

 basal diameter. The outer lip is simple, acute, and well 

 rounded in front ; the pillar is simple, gently curved, and 

 not distinctly reflected. The ordinary length is at most 

 the seventh of an inch. 



The animal is unknown. 



S. Devon (S. H.) ; Falmouth, Sandwich, Tenby, Swan- 

 sea, and adjacent bays (Jeffreys); Scarborough (Bean); 

 Northumberland (Alder); Cork harbour, and elsewhere, in 

 Ireland (Thompson). 



A. NiTiDissiMA, Montagu. 



Aciculate, smooth or with microscopic spiral striulae : no longi- 

 tudinal sculpture. 



Plate XC. fig. 6, 7. 



Tuibo nitidisslmus, MoNT. Test. Brit. vol. ii. p. 299, pi. 12, f. 1. — Maton and 

 Rack. Trans. Linn. Soc. vol. viii. p. 175. — Tiirt. Conch. 

 Diction, p. 217. 



TiirrilcJla nilidissivui, Fleming, Brit. Animals, p. 304. — Brit. Marine Conch. 

 p. 190, f. 17 (badly). 



