88 JURASSIC, OR 
Var. a. Plate 18, figs. 2 a-b. 
A. mundus. Strachey, MSS. 
Tliis differs from the normal form in its wider umbilicus, 
the diameter of which amounts to one-fourth that of the 
shell. The two fragments in the collection are those of 
larger shells than any of the normal form, and although 
ornamented with the denticulate ridge on the inner whorls, 
the outer whorls are smooth and rounded on the ventral 
surface. 
[Since this was in type, the figures have been corrected (as far as the 
state of the lithographic stones would allow), in conformity with Prof 
lllanford’s instructions.—J. W. S.] 
