285 



volutions are not much raifed, but feparated by a fine line i 

 colour cinereous, marked with fine, approximate, undu- 

 lated lines of brown ; fometimes of a purplifh hue, that 

 cover the whole fhell in a longitudinal direftion : aperture 

 angulated; umbilicus fmall, but deep. Size at the bafe 

 five-eighths of an inch diameter; height the fame. Young 

 fhells are more flattened, or at leafl are broader in pro- 

 portion to their height; but the apex is always produced 

 and pointed. 



This is a very common fpecies on moft of our fliores, 

 but has frequently been confounded with the next, though 

 fo efientially different. 



Do61or PuLTENEY has certainly fallen into this error, 

 in making the T. cinerarius of Pennant, and the umbi- 

 licalis 3.nd cincreus of Da Costa the fame. 



Animal very like that of the T. crajfus, but pa'er; ten- 

 tacula and cirri, or feelers on the fides of the body, rather 

 lefs annulated, the former in fome points of view appear 

 flightlv ciliated: on the forehead a fcalloped membrane 

 divided in the middle. In a very pretty drawing executed 

 by Mr. Henry Boys, we perceive four flender filaments 

 en one fide of the body and three on the other; but in all 

 thofe we have examined there were only three on each 

 fide; and were deilitute of the plume, obfervable in the 

 animal of T. crajfus. It is probable tliefe cirri on the fides 

 may belong to the whole of this genus. 



Troch us 



