181 
DENTALIUM medium, 
TAB. LXXIX.—Fig. 5. 
Spec. Cuar. Shell tapering; mouth round; lip 
sharp; tube somewhat trumpet-formed within, 
or broad at the mouth, and becoming suddenly 
small; external transverse striz or lines of 
growth conspicuous. 
SERIE 
Tus shell is rather thicker than most of the species, it is 
gradually thinner near the mouth, the edge of which is 
sharp, giving the inside a trumpet form, while the outside 
__ ts not expanded. 
I am obliged to the indefatigable Miss E. Hill for this, 
among other curiosities peculiar to the green sand from 
Blackdown; and as I believe it to be rare, I have placed it 
here that it may be an hint to those who have opportunity 
to search for better specimens; it is part of a cast in sand, 
which is united together by a siliceous cement. Fig. 5 
shows the cast of the inside; fig. 6 the cast of half the 
outside broken from the other. 
