CYLICHNA. 509 



on the upper half, is utterly devoid of colour. The surface 

 is smooth, or nearly so, but beneath a lens of high power 

 seems covered with most minute and peculiarly densely 

 disposed wavy spiral striulse. The crown is neither sur- 

 mounted by a spire, nor is it (even in the fry) truly umbi- 

 licated, but seems shallowly indented, and filled up, as it 

 were, with a callus. The mouth is so narrow for the greater 

 portion of its length as almost to be linear, but becomes 

 dilated below by the oblique recession of its pillar ; above 

 it is deeply sinuated, and becomes more or less patulous at 

 its anterior extremity, where it is very bluntly and broadly 

 rounded. The acute outer lip runs from above in a nearly 

 straight (not being retuse in the middle) and gradually ad- 

 vancing course, until, after curling inward at the lower 

 medial portion, it suddenly recedes with an abrupt arcuation. 

 The columella is broadly reflected, and bends to the left with 

 a somewhat pliciform twist. Full-sized examples, measure 

 from half an inch to five-eighths of an inch in length, and 

 from two to three lines in breadth.* 



The animal is of a linear shape and entire, of a gamboge 

 yellow colour. Its capital disk is very long, somewhat 

 truncate in front, reflected on the shell posteriorly ; this 

 reflected and slightly bilobed portion we regard as com- 

 posed of the united tentacles ; some way in front of their 

 bases are two very minute and obscure eyes. The lateral 

 lobes are linear and slightly reflected. The foot is not at 

 all produced beyond the shell, all of which is exposed. 



* Mr. Jeffreys informs us that the specimen described as BiiUina producta by 

 Macgillivray (Moll. Aberd. p. 335, copied in Brit. Marine Conch, p. 253), was 

 only the young of this species. The Bulla producta of Brown (lUust. Conch. 

 G. B. p. 57, pi. 19, f. 15, 16) looks like a young individual of this species with 

 the lip broken ; and an Irish shell, supposed to be identical with it (^Thompson, 

 Ann. Nat. Hist. vol. xv. p. 314), is assuredly only a cylindrucea in that con- 

 dition. 



