116 MOLLUSCA FROM THE CRAG. 



C. Testa minutd, cylindricd, arcuatd, crassd, politd ; transversim rugidosd ; antice 

 apertd, marline annulatd; postice oblique truncatd, submucronatd. 



Shell small, cylindrical, thick, strong, andglossy, transversely rugose ; anterior 

 extremity open, margin thickened or annulated ; posterior end with an eccentric, 

 obtusely-pointed clausum. 



Length, \ of an inch. 



Locality. Cor. Crag, Sutton. Recent, Britain. 



This shell is not very abundant. The closed termination is obliquely truncate 

 and obtusely pointed, precisely resembling the recent species in that character, but 

 my Crag specimens are not so deeply or regularly ridged or annulated ; and in ten 

 recent individuals that I possess there is no thickened margin at the anterior or 

 open termination, although they are quite as large, and appear to be full-grown 

 specimens. The greatly enlarged figure represents the posterior termination with 

 its obtuse clausum. 



2. C^icum mammillatum. S. Wood. Tab. XX, fig. 4, a — b. 



CLecum mammilmjm. S. Wood. Catalogue 1842. 

 — var. subulatum, t. 20, fig. 4, b. 



C. Testa tereti, arcuatd, subcylindricd, crassd, lavigaid, politd ; antice apertd, margi- 

 nald ; postice clausd ; clauso mammillato, excentrico. 



Shell tubular, curved, subcylindrical, strong, smooth, and glossy ; anterior 

 extremity open, annulated, or marginated ; posterior extremity with an elevated, 

 mammilliform, projecting, excentric clausum. 



Length, ^ of an inch. 



Locality. Cor. Crag, Sutton. 



Although this species is exceedingly abundant in the Coralline Crag, I have as 

 yet been able to obtain it only from one locality. From its perfectly smooth and 

 glossy exterior, as well as from the elevated and papilliform character of its 

 clausum, I have considered it to be distinct. The shell is thickened a little behind 

 the margin, which is somewhat thin and sharp, and one specimen has what appears 

 to be the remains of coloured bands, as if the shell, when recent, was not quite 

 white. The mammillated and projecting portion of the closed termination is near 

 the outer or curved side of the shell, and stands up prominently to a considerable 

 height. The general form of this species is nearly cylindrical, with the diameter 

 of the closed end almost equal to that of the other, but some specimens are of a 

 subulate or tapering shape, having the diameter of the open end more than twice 

 that of the closed one, which induced me at one time to consider it a distinct 

 species (fig. 4 b), but a slightly tapering form may be also observed in some of the 

 specimens of C. Trachea. The thickened margin is, I imagine, the result of age, 

 and not a specific character. 



