LAND AND FRESH WATER MOLLUSCA.
175
their habits and distribution," by the late J. Gwyn Jeffreys, F.R.S.
(1862-9), which is still the standard manual on the subject. It is pub-
lished by Van Voorst, price, with plates uncoloured, £4. (The Land
and Freshwater species are comprised in Vol. I., price 12s., and Vol. V.,
plates, £1 12s., or coloured, £2 17s.) Other very useful works are :
Dr. Gray's edition of Turton's "Manual of the Land and Fresh-
water Shells of the British Islands" (Longmans & Co., 1857, with
coloured plates, 15s., but now to be had cheaper at Wesley's and
Wheldon's); Rimmer's "Land and Freshwater Shells of the British
Islands" (Allen, 1880, 10s. 6d., plates); Tate's "British Mollusks"
(Hardwicke, with coloured illustrations, 6s.); and last, but not least,
Mr. Harting's own "Rambles in Search of Shells, Land and Fresh-
water" (Van Voorst, 1875, coloured plates, 7s. 6d.), in which the
species are grouped in accordance with the soils they frequent, and
which will be found to be a most useful guide to the beginner in
conjunction with the other works mentioned. A very valuable
series of papers will be found in the "Journal of Conchology"
(Leeds, Taylor Bros.), the editor of which is preparing an exhaustive
Monograph of British Land and Freshwater Mollusca, treating fully
of their variation, structure, and development.—Ed.]
Discussion.
At the delivery of the above address at the Field Meeting in the forest (ante
page 167) the following remarks were made :—
Professor Meldola, F.R.S., hoped that the practical effect of the address would
be a considerable increase of our knowledge of the distribution and habits of this
class of animals in Essex by the efforts of the members themselves, in response to
Mr. Harting's appeal. He believed that very little had been done in tracing a
connection between the variation of the colour, etc., of shells and their environment
and peculiar habits. Judging from the large range of variability which was shown
by many species of mollusca, he thought that some interesting results might be
thus arrived at. Collectors should note carefully the nature and colour of the soil,
the plants and places of rest upon, and in, which the shells were found, so as to
determine whether any and what advantages in concealment and protective resem-
blances were to be traced to the colour variation so frequent, for instance, in the
genus Helix, Such enquiries had been found to be most fruitful by students of
other classes of animals, and there was no reason to suppose that the Mollusca
were wanting in those means of escape from enemies which had been detected so
commonly in other invertebrata.5 He might also remind members that we had
in Essex a considerable extent of sea-board, and he suggested that the marine
and estuarine mollusca of our Essex coast should not be neglected by collectors
living in suitable localities.
Mr. Walter Crouch, F.Z.S., said that Mr. Harting was about right in his
estimate of the number of species of land and freshwater molluscs in Britain ;
5 Mr. R. M. Christy called attention to a supposed case of "protective resemblance" in the
genus Clausula at a meeting of the Club on December 16th, 1382. "Proceedings E. F. C.,''
vol. iii., p. 92.—Ed.