182 DESCRIPTION OF SHELLS. 
divided into large compressed tubercles, the lower half transversely sulcated 
with tuberculated ridges between the furrows ; all the whorls alike. 
A large shell between Cer. gigantewm and Cer. Cornu-copie ; it is a much 
rougher shell than the former, and unlike the latter, is uniformly sculptured 
throughout its length, and increases regularly, not more rapidly, as it grows 
older. 
It is a curious fact, that a third large species of Cerithium should be found at 
a place which already possesses the two above-named large species, found at 
distant localities in France, and at no other place in England. I first noticed it 
in Mr. Bowerbank’s Collection. 
Cerithium hexagonum. 
This sometimes occurs very large. 
Cerithium cancellatum. (Tab. IX. fig. 22.) 
Spec. Cuar.—Turrited, subulate ; whorls convex, numerous, longitudinally 
costated ; costz arched, crossed by three sharp ridges on each whorl. 
Five times as long as wide. 
Somewhat like Certthium clavus, Lam., but longer and with more convex 
whorls ; it appears to be extremely rare. 
Cerithium marginatum. (Tab. VI. figs. 4 & 5.) 
Spec. Cuar.—Turrited, conical or subfusiform, longitudinally and trans- 
versely striated, hence imperfectly granulated; upper edges of the whorls pro- 
minent, bordered with obscure tubercles. 
Width 2, length 5. 
By seven or eight transverse striz and numerous lines of growth, the surface 
is irregularly divided into rows of flattened tubercles, the upper of which is the 
largest and forms a kind of margin to the whorls. This species is rather ob- 
scurely marked in consequence of the specimens being in a bad state of preser- 
vation, and having their surfaces worn. 
Cerithium semicoronatum, C. semigranulosum, C. muricoides, and C. wnisulcatum 
are in Mr. Edwards’s Cabinet. 
Cerithium nudum, C. variabile, and C. emarginatum, have also been found at 
Bracklesham. 
