186 GASTEROPODA OF THE INFERIOR OOLITE. 



It lias been traced in the Cotteswolds (No. 2 district) as far as Horton Hill 

 (Sodbury), where it occurs in the equivalents of the Upper Trigonia-grit. North 

 of this point it has not hitherto been obtained. 



Genus — Cerithinella, Gemmellaro, 1878. ' Faune Giuresi,' &c, p. 282. 



Shell subulate, conical-elongate, subcylindrical ; whorls numerous, nearly fiat, the 

 surface puckered and ornamented with spiral lines. Aperture quadrangular, with a 

 very short anterior canal. 



The shells described by Gemmellaro under Cerithinella are extremely elegant 

 in form, being externally not unlike some of the more cylindrical Nerinesas, though 

 internally the arrangement is quite different. The spiral system of ornamentation 

 predominates. He describes and figures eight species from the crystalline Lime- 

 stone of Montagne del Casale in Sicily, which appears to be of Liassic or Lower 

 Oolite age. 



We have in the Lower Division of our Inferior Oolite a few extremely elegant 

 Nerinasoid fossils, which display considerable resemblance to the Cerithinellae of 

 Gemmellaro. The chief difference consists in the sutural sulcus being more open 

 in the majority of our specimens. The group also occurs in the Lias, where it is 

 represented by such forms as Cerithium confusum, Tate (' Geol. Mag.,' 1875, 

 p. 205), described from the Spinatus -zone of the neighbourhood of Banbury. 

 Probably also some of the so-called Turritellm of the Lias might be referred here. 

 If I am right in classifying our fossils under Cerithinella, the genus is perhaps 

 more nearly allied to the Turritellidas than to the Cerithiiclge. Placed by Fischer 

 provisionally in the latter family. 



116. Cerithinella Bajocensis, sp. nov. Plate XII, figs. 1 a, 1 b, 2, 3. 



Description : 



Length (estimated) . . .35 mm. 



Width . . . . .7 mm. 



Spiral angle .... 10°— 12°. 



Shell subcylindrical, somewhat turrited ; spiral angle slightly convex at first, 

 afterwards regular. Number of whorls eighteen to twenty, constricted rather 

 below the middle, rising slightly towards the sutural sulcus. The subapicals 

 have two nodular spiral belts, the posterior being the most prominent, and 



