is so singular, that 1 hesitated in determining its genus. It has the pro- 

 minences of a murex, the folds of a volute, and the general appearance, 

 with the notch, of a huccinum ; and yet, its other characters and agree- 

 ments, determine its place to be among the cancellariae. He describes 

 two species of this genus as fossils : C. costidata and C. volutdla. 



XIX. Nassa. An oval univalve, the opening terminating inferiorly 

 witli an oblique notch, a little channelled ; the base of the columella 

 hiding the notch, in part, and appearing to be obliquely truncated. 



It does not appear that any fossil shells of this genus are known. 



XX. Purpura. An ovate univalve, its surface being rather rough 

 with spines or tubercles ; the aperture notched, and slightly channeled 

 in the lower part; the columella naked, flat, depressed, and terminating 

 in a point at the base. 



Purpura lapillus, Buccinum lapillus of Linnaeus, is the only species found 

 fossil by Lamarck. 



XXI. Buccinum.. An ovate elongated univalve ; opening oblong, 

 notched in the lower part, and with no canal ; columella convex, full 

 and naked. 



Bruguiere reduced the Linnsean genus Buccinuin, by taking from it 

 the genera terebra and cassis. Lamarck has carried this reduction still 

 further, by forming, with some of the shells, the genera tonna, harpa, 

 nassa, &c. Those shells only are now disposed by Lamarck, under the 

 genus Buccinum, as possess the above characters. 



Buccinum Stromboides, Lam. from Grignon, is distinguishable by its 

 full slightly ribbed lip, which forms somewhat of a stromboidal sinus at 

 its attachment to the spire. This shell in general possesses a considerable 

 polish : and, as in this specimen, Plate V. Fig. 20, it frequently shows 

 some of its original colour. It appears that six species have been found 

 in the environs of Paris : B. stromboides, B. striatulum, B. terebrale, B. de- 

 cussatum, B. bistriatum, and B. clavatulatum. 



B. bistriatum, and B. decussatum, of Lamarck, are, I suspect, both 

 found in the Essex cliff. 



XXII. Eburnct. An oval or elongated univalve, the right edge very 



