(41) 
from the Quarries on the eastern side of Cat-Down, 
are all Unevalves. 
What is a still more curious circumstance, and 
corroborative of the above remark, Univalvé' and B:- 
valve Shells, in one particular instance, are seen to 
occupy parts of the same hill, although in beds 
perfectly distinct, the one from the other. On the 
South side of Stonehouse Hill, for example, (already 
so often mentioned) Univalves only are found; while 
on the North side, Bivalves exclusively prevail. | 
Besides, the shells from our rocks seem to have 
other characteristic marks, which constitute an appa- 
rently essential distinction between them, and which, 
are too obvious to be passed over in silence. Some 
are of a softer nature than others, are more friable, 
and retain more of that shelly or silky texture, fre- 
quently seen in the decayed shells of the present 
day; which would indicate, that they were of a 
more recent period: some, on the other hand, are 
fine grained, compact, hard, and capable of receiving 
a very high polish; in short, participating most fully 
in the properties and colour of the matter in which 
L 
