9148 Mollusks. 
so long overlooked it. Can you on your visit take a strong wedge or 
lever and good hammer, and get for the Museum at Oxford and the 
Geological Society a couple of large demonstrative specimens? Are 
the holes equally numerous on all sides of the hill, or on what aspect 
do they more abound? Are the apertures always so much inclined 
downwards that rain water will never lodge in them? Dothey seem 
to have been made by more than one species of snail, and what species ? 
I found them in Cumberland made by small wood snails. 
William Baker to Prof. Buckland. 
May 14, 1842. 
I have now procured [from Cannington Park] some large and good 
specimens of the perforated limestone. The most illustrative speci- 
men shows weather-worn indentations and holes distinct from those 
made by snails. It weighs more than} cwt. Shall I reduce it by 
chipping off the least interesting parts? The effects of the weather 
are seen on the upper surface and sides of the stones, and the opera- 
tions of the snails are from the sides and under parts, commencing 
near the surface of the ground. The holes are unlike those of Pho- 
lade and the boring Mytilide ; they are pretty large at the entrances, 
enlarging and often branching within in very irregular courses and 
dimensions ; their direction is generally upwards, and they sometimes 
pass quite through to the top of the stone in smaller perforations ; 
several holes sometimes run one into the other, and form capacious 
chambers, sufficient for the habitation of many snails. The outer parts 
of the holes are often lined with minute lichens, but within they show 
more and more freshness towards the further extremities, where there 
is generally evidence of very recent operation. These perforations 
are found on all parts of the hill, but more abundantly in blocks partly 
concealed by small bushes and herbage. ‘They are in blocks which 
stand out from the turf, and in those which have been buried by earth 
washed over them by rains. There are none to be found in places 
which are not now accessible to snails, or which have not been so 
recently. Almost all the holes contain either living snails or shells. 
The only species which I have found in them are Helix aspersa and 
nemoralis. The former are the most abundant ; indeed, I believe the 
perforations are made chiefly by this species. On lifting up some 
large flat blocks that snails could pass freely under, and which afforded 
them a snug shelter, I found large accumulations, many hundreds of 
shells and living snails. ‘The under surface of these blocks had large 
