159 
HELIX ? striatus, 
TAB. CLKXI.—fig. 1, . 
Spec. Cuar. Conical, depressed, subcarinated, 
obliquely striated, a rising band around the 
edge, crossed by arched strie ; columella solid, 
aperture subtriangular. 
ae 
Tver isa great resemblance about the base of this 
shell to the genus Trochus, given it by the prominent co- 
lumella ; in other respects it strongly resembles Helix 
carinatus, (see tab. 10.*) from which it differs in not hav- 
ingan umbilicus, in the greater distance and sharpness of 
its strie, and the strong arched striz upon the band. 
From the Limestone of Derbyshire, collected by Mar- 
tin ; the place of the shell is occupied by granular Carbo- 
nate of Lime, and the inside filled with grey Limestone. 
Had not the general form strongly resembled the 
Helix above mentioned, I might have been induced 
to have placed this as a Trochus, although it does not 
precisely accord with the characters of that genus. I 
might have formed a new genus of the two, to which the 
following species should have been added, did they not 
differ materially from each other in the characters that 
should distinguish it. Besides the aperture is very im- 
perfect in them all. Itis probable that other species may 
be found, and that by their help and that of more perfect 
specimens, the genera they belong to may be determined, 
or the characters of new ones ascertained, and this is the 
more desirable as they appear from their localities to be 
marine inhabitants, rather than land shells. 
* In the description of this the striz are said to be transverse instead 
of oblique by mistake, and the striz upon the lower part have escaped 
notice, 
