80 



and rounded; with the margins disjoined in the upper part; and a 

 notch in the right lip. 



As it appeared to be necessary to separate the genus Vis from Bucci- 

 num, in consequence of the turriculated shape of the former shells, so it 

 is necessary to separate Turritella from Turbo, Cydostoma, Pupa, and Sea- 

 laria ; the shells of the genus Turritella having all a notch at the right 

 side of their opening, which is not the case with any shell of the other 

 four genera. 



Turritellites perforatus, Lam. Plate V. Fig. 12, is a very curious 

 species of this genus, the columella being perforated through the whole 

 axis of the shell. This peculiarity exists in the shell here figured : but 

 it does not exactly agree with that which is described by Lamarck ; 

 since its turns are smooth, while those of the shell which he describes 

 have three or four transverse striaB. The difference may be only that of 

 a variety ; or the surface, in my specimen, may be somewhat altered 

 by decomposition or friction. 



In a large fossil shell of this genus, now before me, a very curious cir- 

 cumstance is observable. The shell has been completely fractured 

 across, and afterwards united by that astonishing power of reparation, 

 which is perhaps possessed by all shell-fish. 



Some species of this genus are found in Hampshire, particularly T. te- 

 rebellata, Lam. Turbo terebra, Brand. T. imbricataria, Lam. and Turbo 

 editus, Brand. This latter shell has been found, very fine, in the neigh- 

 bourhood of Selsea, with several other of the same shells as are found in 

 Hordwell Cliff, by Mr. J. Hplloway, of Portsmouth. This gentleman, 

 to whom I am obliged for this information, and for several of these spe- 

 cimens, relates that he also found this shell, with others which I shall 

 have occasion to notice, in a blue mud at the base of Stublington Cliff, 

 between Stoke's Bay and Southampton. 



Among the pyritical shells of the Isle of Portland are frequently found 

 shells of this genus. Impressions of shells of this genus, as well as of 

 the genus -Cerithium, are frequently seen in the Portland free-stone. 



