120 TESTACELLA SCUTULUM, SOWERBY.
When examining gravel pits and sections I have very frequently
taken away with me a sample of the smaller stuff for examination at
home, and I found the proportion of Lower Greensand chert in these
samples was as follows :—
These figures seem to show that in pre-glacial or early glacial
times there was a considerable flow of water from the south towards
the north, unless indeed it can be shown that this chert came from
the Lower Greensand of the north.
I am not, however, at present able to find any record of such a
rock occurring in the Lower Greensand north of London, but the
matter requires further investigation.
TESTACELLA SCUTULUM, SOWERBY.
THE specimens of this worm-eating slug, recently exhibited at a
meeting of the Essex Field Club,1 have furnished the material
for some experiments and called forth a paper in the "Zoologist" from
our member, Mr. W. M. Webb, F.L.S.,2 dealing with the way in
which this highly specialised mollusc catches and swallows its prey.
The first part of the paper is taken up by a review of the pre-
vious accounts of the matter, which, however, tend to the formation
of somewhat exaggerated and indefinite ideas on the subject. A
description is then given of the writer's experiments ; he found that
certain stimuli, such as the touching of the retracted anterior end of
the slug by a living earthworm, or with a camel's hair brush, or again
with a drop of water in the case of Testacella maugei, Fer., gave rise
1 Essex Naturalist, vol. vii. (1893), p. 46.
2 On the Manner of Feeding in Testacella scutulum, by Wilfred Mark Webb, F.L.S, Staff
Demonstrator in Biology to the Essex County Council, "Zoologist," vol. xvii. (1893), pp. 251-
289, plate 1.