GASTEROPODA. 73 



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

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



Jxis, ^ of an inch. 



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



This specie^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 granidated 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 repaii-ed by the animal. When perfect, the lower 

 part of the outer lip is a little expanded, gi\'ing 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. Certthium granosum. 8. Wood. Tab. VIII, fig. 9. 



Cerithium granosum. S. TVood. Catalogue 1842. 



C. Testa subiilafo-turrifd, sinistrorsd ; apice ohtuso; anfractibus convexiusculis, trans- 

 versim quadri vel quinqite striatis, striis elevatis, tuber culato-granoHis ; canali hrevi, recurve. 



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 descrip- 

 tion 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 wnder space above the 

 suture : my best specimen has twelve volutions and an obtuse apex. The first two 

 whorls differ from the others in being shaqily costated longitudinally, and finely 

 striated transversely. The base in all my specimens is free from striiE. WTien the 

 granules are worn down, the surface of the shell appears regularly cancellated. 



10 



