176 GASTEROPODA OF THE INFERIOR OOLITE. 
Genus—CrriteLta, Morris and Lycett, 1851. 
“ Shell turrited, 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 Bathonian 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. Géol. France,’ 2™ sér., t. 138, 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 Ceritelle 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 Ceritellz can be regarded 
as at all abundant, two very distinct sections may be noted, viz. species which 
have the shell perfectly smooth, such as CO. wnilineata and OC. 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 
(‘ Proce. Cottes. Nat. Club,’ vol. i, p. 80, pub. 1853) describes Ceritella sculpta 
and Ceritella tumidula 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 lke that of certain forms of Nerinzxa 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. 
