' 
24 MOLLUSCA FROM THE GREAT OOLITE. 
Locality. \t would appear to be very rare, and has been found only in the planking of 
Minchinhampton Common ; but with this and other minute shells it is not easy to form an 
accurate notion of their actual numbers. In the Bath Oolite of Langrune, Normandy. 
(Desl.) 
Bracuytrema. JVov. Gen. 
Fusus. Species in part. Awet. 
The Great Oolite shells, which we have placed under this generic designation, present 
characters so much at variance with the received ideas of Fusus, that we have been induced 
to erect them into a new genus, under the name Brachytrema ; the definition of this form, 
whether it be regarded as subdivision of /wsus, or as a distinct genus, is as follows :— 
B. Testa turrita, turbinatd ; anfractibus conveais et costatis, nodulosis, aut cancellatis ; 
labro dextro tenui ; columella rotundatd, levi, ad basin contortd; canali brevi, obliquo. 
Shell small, turreted, turbinated; whorls either costated, nodulated, or cancellated ; 
the last whorl large and ventricose; right lip thin and smooth; columella smooth, rounded, 
twisted near to the base, and reflecting outwards, forming a short oblique canal; aperture 
moderately large, subovate, its length being usually less than that of the spire. 
The general figure of this genus is turbinated, and nearer to Buccinum than Fusus ; it 
has, however, the base and channel of Cerithivm; the short oblique canal and twisted 
columella separate it from Fwsvs, the genus to which the known species have most 
frequently been referred. ‘The following forms may possibly be assigned to this genus :— 
Murex haccanensis of Phillips, the Fusus carinatus of Roemer, the Triton buccinoideum, the 
Purpura filosa, the Murex versicostatus, and the Fusus corallensis of Buvignier, and, pro- 
bably, the Fusus nassoides and the Fusus nodulosus of Deslongchamps. All the species are 
small, the largest scarcely equalling 10 lines in length. 
The Fusus Thorenti V Archiac would appear at first sight to belong to this genus; but 
having examined the original specimens in the collection of Viscomte d’Archiac, we are 
inclined to believe that the figure in the ‘Memoirs of the Geological Society of France’ 
(vol. v, plate 30, fig. 8), is taken from an imperfect shell, which is closely allied to, if not 
identical with, the Zirbo pyramidalis of the same author. 
BRACHYTREMA BUVIGNIERI. Plate V, fig. 7. 
B. Testa conicd, turbinatd, apice obtuso; anfractibus 5 planatis, et costulatis; costis (14) 
longitudinalibus, clatis, lineas transversas numerosas, elatas, distantes gerentibus. 
Shell conical, turbinated, apex obtuse, whorls 5, flattened and costated ; costa longi- 
tudinal, elevated, about 14 in a volution, and impressed by transverse lines: the lines are 
