90 LAND AND FRESH-WATER MOLLUSKS. 
though living in immediate contact with marine 
conditions, is truly pulmoniferous ; it occurs on 
the rocks at West Comb, in Lantivet Bay, be- 
tween Polperro and Fowey, Cornwall, where it 
was discovered by Mr. Couch. They congregate in 
little groups about a foot or so from the margin 
of the sea where the waves break over them, 
ascending and descending so as to maintain 
their distance as the tides fluctuate. 
A few words more as to the methods by which 
slugs may be preserved :—As regards the inter- 
nal shell, it may be obtained by making a crucial 
incision in the shield, taking care not to cut down 
upon the calcareous plate, which can then be re- 
moved without difficulty. The animals can only 
be conserved by keeping them in some preserva- 
tive fluid; but the great object to keep in view, 
is to have the slug naturally extended. Most 
fluids contract the slugs when they are immersed 
in them. The slugs should be killed whilst 
crawling, by plunging them into a solution of 
corrosive sublimate, or into benzine. Models in 
wax or dough are sometimes substituted for the 
animals. A writer in the Naturalist gives a pro- 
cess for the preservation of slugs, which he states 
to answer admirably, and to be very superior to 
spirit, glycerine, creosote, and other solutions :— 
“ Make a cold saturated solution of corrosive sub- 
limate ; put it into a deep wide-mouthed bottle ; 
