14. MOLLUSCA FROM THE GREAT OOLITE. 
which is cited by that author as occurring both in the Great and Inferior Oolite of 
Normandy. We also possess the same species from the Inferior Oolite of Bridport and 
Gloucestershire. It differs, however, essentially from the original specimen of 4m. discus, 
Sow., described in the ‘ Min. Conch.,’ tab. 12, which has a more regular, sagittate aperture, 
and does not possess the central flattened space, so characteristic of our species. 
Locality. Great Oolite of Minchinhampton, Zycett. In the same formation at 
Ranville (Calvados), Niort (Deux Sevres), Mansigny (Vendée), D’ Orbigny. In the Inferior 
Oolite at Bridport, and near Stroud; Eterville and Moutiers (Calvados). 
We have much pleasure in assigning to this species the name of G. R. Waterhouse, 
Esq., whose arrangement and careful study of the Cephalopoda, contained in the National 
Collection, have materially assisted this branch of Palaeontology. 
Cuass-—GASTEROPODA. Cuvier. 
ORDER— PROSOBRANCHIATA. VW. Edwards. 
CTENOBRANCHIATA, Schweigger. 
Family—STROMBID. 
Prerocera, Lamarck, 1801. 
Shell turrited, ventricose, spire usually short, aperture oval, having a lengthened canal at 
both extremities, outer lip expanded into hollow thickened spies, with an anterior sinus 
separate from the caudal canal. 
Prrrocera 1GNoBinis. Plate III, fig. 14. 
P. Testa parva turbinata; spird breviusculd; anfractibus levigatis, planatis (3—A) ultimo 
obsolete transversim bicarinato; carind superiori obsolete nodosa; cauda brevi. 
Shell small, turbinated, spire short, whorls smooth, flattened (3—4), the last whorl twice 
carinated, the upper carina obscurely nodulous, canal short. 
The great breadth of the whorls, and the obscurely bicarinated last whorl, are the leading 
features. This shell approaches A/aria levigata; but in that species the spire is much more 
lengthened, and the volutions do not become angular, until at least five have been com- 
pleted, it then produces small processes, which are deciduous, and the last whorl does not 
attain any undue magnitude ; but, in the species before us, the fourth volution is large, has 
considerable squareness, but with scarcely any distinct carina. 
Locality. Rare in the planking of Minchinhampton Common. 
