GASTEROPODA. 73 



Shell small, subcylindrical, especially the lower half; volutions flat, with three 

 granulated ridges ; apex acute ; canal short, recurved, and nearly closed. 



Axis, T 5 B of an inch. 



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



This species is not by any means rare in the Coralline beds, though I have not 

 yet seen it from the Red Crag. There is, I think, no doubt of its identity with the 

 recent British shell. It has commonly three granulated ridges on the body of the 

 whorl, the middle one of which is generally the smallest ; and sometimes there are 

 only two, with two plain ones on the base of the last volution. The last whorl is 

 rather contracted, which gives a cylindrical form to the lower half of the shell. A 

 kind of canal is formed at the suture by the elevation of the ridges. The mouth 

 is often broken, and several of my specimens show that it has been repaired by 

 the animal. When perfect, the lower part of the outer lip is a little expanded, 

 giving the mouth a subquadrate form, with a deep sinus in the upper part at the 

 suture. The canals are never quite closed at either extremity of the aperture in 

 any of my specimens. 



9. Cerithium geanosum. S. Wood. Tab. VIII, fig. 9. 



Cerithium granosum. S. Wood. Catalogue 1842. 



C. Testa subulato-twritd, sinistrorsd ; apice obtuso ; anfractibus convexiuseulis, trans- 

 versim quadri vel quinque striatis, striis elevatis, taker culato-granosis ; canali brevi, recurvo. 



Shell elongate, turriculate, and tapering ; whorls sinistral, slightly convex, 

 covered with four or five granular ridges, aperture subcircular; canal short and 

 recurved. 



Axis, f of an inch. 



Locality. Cor. Crag, Sutton. 



Red Crag, Walton Naze. 



Imperfect specimens of this shell are by no means rare, but I have nothing 

 that will show the mouth entire. It appears so very different from the figure and 

 description of C. sinistratum , Nyst (Coq. foss. de Belg. p. 541, pi. 42, f. 10), that I 

 cannot imagine the two to belong to the same species, unless the Belgian shell has 

 undergone a material alteration by the removal of the granular ridges. The 

 volutions of the Crag shell are rather more conoidal than convex, with four or five 

 nodose ridges when the shell is perfect ; the lower one rather projecting, with 

 a wider space above the suture : my best specimen has twelve volutions and an 

 obtuse apex. The first two whorls differ from the others in being sharply costated 

 longitudinally, and finely striated transversely. The base in all my specimens is 

 free from striae. When the granules are worn down, the surface of the shell 

 appears regularly cancellated. 



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