LAND AND FRESH WATER SHELLS. 
245 
species arc those only which have as yet been no¬ 
ticed as belonging to South Devon, but they are 
those of which I could procure authentic inform¬ 
ation, not doubting at the same time that we claim 
many of those kinds with Cornwall which are now 
ranked pro tempore as peculiar to that county, and 
according to this view of the subject it is but a 
provisional and arbitrary proceeding to mark any 
species as limited to the one county or the other, 
though perhaps many kinds are confined to the 
south-western shores aggregately considered. 
MOLLUSCA. 
CATALOGUE OF THE LAND X FRESH WATER SHELLS OF SOUTH 
DEVON, WITH REMARKS ON THEIR HABITATS, £C. 
The species marked with an asterisk have been found (as regards 
Britain) only in this district, or at most in the county as a 
whole. The nomenclature of Turton’s Manual is adopted. 
(BIYALYE.) 
Cyclas pusilla. — In stagnant pools, running 
water, and spots flooded by rivers. We have a shell 
here, found in the same situations, of a rust colour, 
but differing so little in shape as to be entitled to 
consideration only as a variety of the above. 
Unio margaritiferus_In rapid rivers. Dead, and 
occasionally living specimens are found in the sand¬ 
pits dug in the banks. These specimens are 
always numerous in proportion to the quantity of 
rain which falls in the autumn and winter; the 
violence of the stream being thereby increased, 
the shells are driven into these catch-pits. A person 
