176 GASTEROPODA OF THE INFERIOR OOLITE. 



Genus — Ceeitella, Morris and Lycett, 1851. 



" Shell tarrited, spire acute, subulate, volutions flattened, their margins usually 

 sulcated; the last whorl large, aperture lengthened and oblique, canal very short ; 

 columella smooth, rounded, and slightly reflected at the base; outer lip thin.*' — 

 ' Gt. Ool. Moll.,' p. 37. 



This is so essentially a Batlionian genus that it is hardly necessary to say 

 much regarding it in this Memoir. It is well known that Piette in 1856-57 

 (' Bull. Soc. Geol. France,' 2 me ser., t. 13, p. 592, and t. 14, p. 558) constituted 

 the genus Tubifer to receive a group of shells from the Bathonian of the 

 Ardennes, which are, on the whole, very similar to the Ceritellse of Morris and 

 Lycett. Fischer (' Manual,' p. 684) regards Tubifer as a subgenus of Ceritella, 

 having the form of an Actxon, the last whorl cylindrical and strongly developed. 

 Cossmann (op. cit., p. 108) does not regard Tubifer as being even a subgenus. 



In the Great Oolite of Minchinhampton, where alone Ceritellge can be regarded 

 as at all abundant, two very distinct sections may be noted, viz. species which 

 have the shell perfectly smooth, such as C. unilineata and C. Sowerbyi, and those 

 which are sculptured longitudinally as in C. conica. An impressed line on the 

 shoulder of the whorls is a frequent characteristic of the smooth species, but 

 appears to be absent in Ceritella acuta. 



In the Inferior Oolite of this country Ceritella is extremely rare, and none of 

 the forms attain even to the size of the little shells from Bathonian beds. Lycett 

 (' Proc. Cottes. Nat. Club,' vol. i, p. 80, pub. 1853) describes Ceritella sculpta 

 and Ceritella tumidida from the Inferior Oolite of Gloucestershire. These I have 

 not seen, nor are they mentioned in the lists of the ' Handbook to the Cotteswold 

 Hills ' published in 1857. As far as my present opportunities extend I have not 

 been able to determine any species of Ceritella from the Inferior Oolite of the 

 Cotteswolds, though there are some small forms in the "Lower Limestone" of 

 the Stroud-Nailsworth district which rather suggest this genus, but these are 

 too imperfect for description. However, since the physical resemblance of these 

 beds to the Minchinhampton beds is considerable, we may expect to find Ceritella 

 in them. The Lincolnshire Limestone seems to be the only part of the Inferior 

 Oolite which has hitherto yielded Ceritella. A few specimens have been found at 

 Weldon and at Ponton. These most resemble the smooth species with sulcated 

 margins, such as C. Sowerbyi. The body- whorl is cylindrical, and the general 

 aspect of the shells so much like that of certain forms of Nerinxa that it has 

 been found necessary to cut sections for the purpose of ascertaining the internal 

 structure. With considerable variety as to width there seems too much general 

 resemblance to constitute more than one species. 



