54 MOLLUSCA FROM THE CRAG. 



striae I presume are the fine lines of growth, more especially visible where the shell 

 has lost part of its outer coating. I have figured two individuals, both of which are 

 rubbed and worn. 



3. PLEUROTOMA CARINATA. Biv. Tab. VI, fig. 2, a, b. 



PLEUROTOMA CARINATUM. Bivonce in Philip. Enum. Moll. Sic. vol. ii, p. 1/6, t. 26, fig. 19, 1844. 



PI. Testa fusiformi, turritd ; anfractibus septem, Itevissimis, subangulatis, carinatis, 

 superne concavis, infra convexis ; aperturd ovatd ; canali elongatd ; labro acuto. 



Shell turriculate and fusiform ; volutions smooth, with a prominent keel about the 

 middle, concave above the keel, convex below it ; aperture ovate ; canal elongated, and 

 rather broad. 



Axis, f of an inch. 



Locality. Cor. Crag, Gedgrave. 

 Red Crag, Sutton. 



I have but one specimen from each formation. These shells have about eight 

 volutions, with the keel a little above the centre of the whorl. Dr. Philippi describes 

 his shell as having a prominent and elevated keel. In the Crag specimens it is only 

 sharply angulated, being, perhaps, worn at that part. The position of the sinus is not 

 distinctly defined in either of my specimens. Probably it was a little above the 

 keel. 



4. PLEUROTOMA SEMICOLON (?). /. Sow. Tab. V, fig. 3, a b. 



PLEUROTOMA SEMICOLON. J. Sow. Min. Conch, t. 146, fig. 6, 1816. 

 COMMA. - t. 146, fig. 5. 



PL Testa elongato-fusiformi, turritd; anfractibus numerosis conveccis, superne concavis, 

 medio nodulosis ; transversim striatis vel cingulatis, prope suturam granulatis ; aperturd 

 elongato-ovaid ; canali angustd. 



Shell elongate and fusiform, variable, whorls convex, covered with striae or bands ; 

 spire crenulated, aperture elongate, outer lip curved ; canal rather variable in length. 



Axis, f of an inch. 



Locality. Cor. Crag, Gedgrave. 

 Red Crag, Sutton. 



I have but a few specimens of this species in good preservation. It appears, how- 

 ever to correspond with one of the varieties of that variable and well-known shell 

 from Barton and Bracklesham, where it is abundant. This is one of the few Eocene 

 shells that may be considered as having lived on to the Crag period. The sinus of our 

 shell is situate in the upper and most projecting part of the volution, at which place 

 there are two rows of nodules ; these are carried up the spire like the marks of punc- 

 tuation which suggested the name to Mr. Sowerby. The Crag species appears a variety 

 of P. semicolon ; there is one ridge near the suture, above the concave part of the 



