160 
INOCERAMUS striatus. 
TAB. DLXXXII. —fig. 2. 
Spec. Char. Subglobose, even, concentrically 
striated, the striae accompanied by shallow 
furrows ; anterior side concave, smooth. 
Syn. Inoceramus striatus. Mantell, Geol.Suss. 217. 
t.W.f.5. 
This rare species has not been found sufficiently perfect 
to exhibit all its characters. Its valves, however, appear 
to be equal, and the beaks very short and blunt. Its 
form readily distinguishes it from I. mytilloides, which 
it accompanies in Sussex and Wiltshire. The specimen 
figured is from Heytesbury. I am indebted to the intel- 
ligent author of the u Geology of Sussex” for it. 
INOCERAMUS involutus. 
TAB. DLXXXIII. 
Spec. Char. Subglobose ; valves very unequal ; 
one gibbose, even, with a large incurved beak 
and very hollow sides, the other nearly flat, 
with deep concentric waves ; its margin very 
thick, deflected ; hinge line upon an elevated 
narrow lobe. 
When once this species has been observed, even frag- 
ments are readily recognized, — especially of the larger 
valve, by the smoothness of its surface and convex form ; 
or of the smaller valve, by the strength of the undula« 
tions, their circular disposition, and the long narrow 
lobe of the hinge, that looks as if the margin were rolled 
over. The flatter valve offers the greatest variation of 
