GASTEROPODA. 75 



striae or ridges are rather irregular, though generally there is one large and one 

 small one alternately : they are all sharp and angular. The ridges upon recent 

 specimens are also irregular in their disposition, having sometimes fine transverse 

 strice between them. Fig. 9 b is from the Red Crag, resembling the general form 

 of the recent shell. Fig. 9 a is from the Mammaliferous Crag at Thorpe, which I 

 presume to be the same species, although it is more subulate in form, with a 

 deeper suture, and more convex volutions. 



2. Turritella imbricataria. Lam. Tab. IX, fig. 10, a — b. 



Turritella imbricatabia Lam. An. du Mus. vol. iv, p. 216, pi. 37, fig. 7, 1804. 



— Desk. Coq. foss. des Env. de Par. pi. 35, fig. 1-2, and pi. 37, fig. 9-10 



— Nyst. Coq. foss. de Belg. p. 397, pi. 37, fig. 5. 

 Turritella conoidea. J. Sow. Min. Conch, t. 51, fig. 145, 1814. 



— S. Wood. Catalogue 1842. 



T. Testa, elongato-turritd, subutatd ; awfractibus planatis, ad basim subangulatis^ trans- 

 versim stria tis, striis imbricafis, vel subtitissime granulaiis. 



Shell elongate, turreted, and tapering, with flattened volutions, slightly angulated 

 at the lower part ; transversely striated with imbricated or finely-granulated strise. 



Axis, 2 inches. 



Locality. Red Crag, Sutton and Newbourn. 



My cabinet contains about thirty specimens of this shell, which is no doubt the 

 same species as the one so abundant in the Eocene formation, at Barton; my 

 specimens are all more or less rubbed, and may probably be a diluvial introduction 

 from the older bed, although that number is rather large for such a casualty. One 

 specimen is covered with fine and regular transverse strias, which though rubbed 

 show the remains of granulations ; the angular form of the base of the volution 

 appears to be its distinguishing character. Fig. 10 b is from a specimen much 

 worn and eroded, and exhibits a more conical form of volution than the generality 

 of these shells. 



3. Turritella incrassata. /. Sow. Tab. IX, fig. 7, a — d. 



Turritella incrassata. /. Sow. Min. Conch, t. 51, fig. 6, 1814. 

 Turbo triplicatus. Brocchi. Foss. Subapenn. t. 6, fig. 14, 1814. 



- duplicatus (?) t. 6, fig. 18. 



IMBRICATARIUS. - - - - t. 6, fig. 12. 



VERMICULARIS. - - - - t. 6, fig. 13. 



Turritella duplicata. Dubois de Montp. Conch, foss. "Wolhyn. Podol. pi. 2, fig. 19-20, 1831. 

 triplicata. Dnjard. Mem. Soc. Geol. de France, torn, ii, pt. 2, p. 287, 1837. 



— Gi-ateloup. Foss. de Dax (Actes de la Soc. Linn, de Bord.), torn, v, 



p. 161, 1838. 



— Nyst. Coq. foss. de Belg. pi. 37, fig. 7-8, 1844. 



— incrassata. S. Wood. Catalogue 1842. 

 bicincta. .... var. j8, fig. 7 d. 



T. Testa lurritd, anfractibus planulatis ; transversim striatis, cingulos duos vel ires 

 obtusos distantes ferentibus ; c'utyulo iutermedio crassiore, supremo obsoleto. 



