74 MOLLUSCA FROM THE CRAG. 



Sect. HOLOSTOMATA. Flem. 



Turritella,* Lam. 1815. 

 Turbo (spec.) Linn. 



Gen. Char. Shell elongate and turriculate, generally thick and strong, tapering 

 to an acute apex, volutions numerous ; aperture entire, subcircular, or slightly 

 quadrate ; outer lip thin and sharp, somewhat sinuous ; operculum corneous and 

 spiral. 



Shells of this genus are generally well distinguished from those of any other, 

 excepting it be perhaps some aberrant forms of Cerithium ; a more or less emargi- 

 nate base distinguishes the latter genus, although in some species this character 

 is very imperfectly displayed. 



As a genus this is not restricted to any climate, some species being found 

 within the tropics, while others are inhabitants of the coasts of Greenland and 

 Scandinavia, and, according to Mr. J. Sowerby, it appears in the Protozoic rocks 

 (vide Sil. Syst.) ; these shells, however, resemble so much in form those of Mur- 

 chisonia, that unless the specimens are very perfect it would be difficult to distin- 

 guish them. There is, however, a well-marked species from the Greensand for- 

 mation. (Vide Min. Con. t. 565.) 



1. Turritella communis. Bisso. Tab. IX, fig. 9, a — b. 



Turbo terebra. Mont. Test. Brit. p. 293, 1803. 



Turritella communis. Risso. Hist. Nat. des princ. Prod, de l'Europe, iv, p. 10G, fig. 37, 1826. 



— terebra. /. Sow. Min. Conch, t. 565, fig. 3, 1827. 



— — Woodward. Geol. of Norf. p. 44, 1833. 



— LiNNvEi. Desk. Exp. de Moree, torn, iii, p. 146. 



Bujard. Mem. de la Soc. Geol, de France, p. 287, 1837. 



— terebra. S. Wood. Catalogue 1842. 



— communis. Phil. En. Moll. Sic. vol. ii, p. 160, 1844. 



— plebeia. Say. Lyell in Proc. of Geol. Soc. 1845, vol. iv, pt. 3, p. 554. 



T. Testa turritd, subulatd ; anfractibus convewiusculis ; transversim lineatls ; lineis 

 8 — 10, elevatis acutiusculis ; aqualibits, vel inaqualibus, cinctis. 



Shell turriculate and tapering, with very slightly convex volutions ; covered 

 with 8 — 10 fine ridges, sometimes equally distributed, at others rather irregular 

 in size and number ; outer lip sinuous. 



Axis, If inch. 



Locality. Red Crag, Sutton. 



Mam. Crag, Bramerton and Bridlington. Recent, British Seas. 



This shell is given by Professor E. Forbes, in his ' Report upon the Existing 

 Fauna and Flora of the British Isles,' as a Coralline Crag species. I have no 

 specimen from that formation. It is, however, very probable it may have lived 

 in the seas which deposited the Coralline Crag, having been given as a Touraine 

 species by M. Dujardin, and as an American Miocene fossil by Mr. Lyell. The 



* Etyrn. From Tun-is, a tower. 



