GASTEROPODA. 97 
aperture, we prefer to regard it as a Bu//a. Upon comparing approximate forms it will 
be found that the figure of the base and cavity of the vertex is much wider than in 
C. pyriformis; the cavity is much more contracted and deeply excavated than in C. du/- 
Jatus; a third shell, which more nearly approximates in form to our species, is the 
Bulla Hildesiensis, figured by Roémer, (Verst. Nord. Ool. Geberges, t. ix, fig. 26,) in 
which, however, the form appears to be more elongated and the aperture more expanded 
towards the base. 
Our shell would seem to be rare; we have obtained it in one small excavation only, 
about 100 feet above the Fullers-Earth, in concretionary sandstone: the dismtegrating 
action of frost has enabled us to detach two specimens, and we have vainly endeavoured to 
extricate several others from a matrix harder than themselves. 
Axis 7 lines, transverse diameter 53 lines, diameter of the cavity 2 lines. 
Locality. A superficial excavation one mile east of Minchinhampton. 
Family—ACTEHONIDE. 
Cyrinprites—WJVov. gen. 
ACTON sp., Sow., D’ Ord. 
Testa subcylindricd vel ovata, spird pared ; anfractibus plerumque planis, marginibus 
acutis, anfractu ultimo cylindraceo, apertura elongatd, superne linearis, inferné integra 
et rotundatd ; columelld ad basim cortortd, labro dextro tenui ad basim crassiort. 
Shell smooth, subcylindrical or ovate ; spire small; whorls usually flattened, with acute 
margins ; the last whorl cylindrical ; aperture lengthened; lmear above ; rounded and 
entire at the base; columella rounded, twisted near to the base, and slightly directed 
outwards ; right lip thin, but thicker at the base. 
The cylindrical figure, flattened and nearly concealed volutions, their acute margins, 
the linear aperture and columella directed outwards at the base, are the characters which 
entitle this group to be separated from Acton (Tornatella Lam.), and constituted a new 
genus, it is in fact a Pyramidella in all but the basal notch ; some of the species will be 
found to approach to the Cones, others the Bulla, in each case more nearly than to Acton, 
Species of this genus also occur in the Inferior Oolite, but they are perfectly distinct from 
those which are here described. 
All the species of this genus have smooth shells ; in Actacon most of the species are 
transversely striated or punctato-striate. 
Mr. Sowerby, in the description of Acfeon cuspidatus, remarks, “So novel is the 
contour of this little shell, that it is with difficulty compared to any before known; it 
agrees, however, with the essential characters of Actaon, but differs in general form, and 
