GASTEROPODA. 97 



aperture, we prefer to regard it as a Bulla. 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. bul- 

 latus; a third shell, which more nearly approximates in form to our species, is the 

 Bulla Hildesiensis, figured by Roemer, (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 disintegrating 

 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 5^ lines, diameter of the cavity 2 lines. 



Locality. A superficial excavation one mile east of Minchinhampton. 



Fam il// — Act^e o n i d ^g . 



Cylindrites — Nov. yen. 



Action sp., Sow., If Orb. 



Testa subcylindricd vel ovatd, spird parvd ; anfractibus plerumque plants, maryinibus 

 acutis, anfractu ultimo cylindraceo, aperturd elonyatd, superne linearis, in/erne inteyrd 

 et rotundatd; columella ad bash/ cortortd, labro dextro tenui ddbasim crassiori. 



Shell smooth, subcylindrical or ovate ; spire small ; whorls usually flattened, with acute 

 margins ; the last whorl cylindrical ; aperture lengthened ; linear 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 Actaeon (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 Actaeon. 

 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 Actseon most of the species are 

 transversely striated or punctato-striate. 



Mr. Sowerby, in the description of Actceon 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 Actaeon, but differs in general form, and 



