DISPERSAL OF SHELLS. 
The | Dispersal of Shells | An Inquiry into the Means of | Dispersal aarnty 
by Fresh-water | and Land Mollusca | By | Harry WALLIs KEw, F.Z.S. | 
with a Preface od Alfred Russel Wallace, LL.D., F.R.S., ete | with 
illustrations. | London | Kegan Paul, Trench, Triibner & Co., Ltd. | . . | 
1893. [International Scientific Series, Vol. 75, crown 8vo., cloth, xiv. +201 
pages, price 5s. 
THIs volume of a series which includes a large number of most 
interesting and valuable works upon an unrestricted variety of 
scientific subjects, is distinctly of a more practical a and of a less 
he 
a collection of hitherto isolated facts now brought into juxtaposition, 
is calculated to be of the utmost possible use to any who may fee 
tempted to enter the field of speculation, with a view of arriving at 
a knowledge of the causes which bring about the dispersal of 
mollusca, 
e book consists of nine chapters. The first is devoted to 
fresh-water shells and to the anomalies in local distribution which 
they present. A number of instances are given on reliable authority 
to show how quickly even isolated pieces of water and new ponds 
receive their molluscan denizens. The second chapter deals with 
the various means of dispersal which have been placed on record, 
and numerous instances to show the tenacity of life which materially 
assist the bivalve mollusca in their involuntary migrations from place 
to place. The ‘transplantation’ of bivalves is dealt with in the 
third chapter, mostly recording their attaching themselves to insects, 
amphibians, birds, etc., and so obtaining their means of transit. 
The transplantation of univalves follows in the fourth chapter, in 
which it appears that operculated mollusca share to some extent the 
numerous. In the fifth chapter, the tenacity of life manifested by 
land shells is demonstrated by the citation of numerous striking 
examples. The means of dispersal of land mollusca are dealt with 
in the sixth chapter, and those of slugs in the seventh. The 
influence of ocean currents, of rivers and floods, of wind and of 
various animal agencies find due mention, fortified by numerous 
recorded instances. The dispersal of fresh-water and land mollusca 
by man—sometimes voluntarily, but mostly unintended by him— 
finds a place in the eighth chapter, and the ninth, a lengthy one, 
deals with the fresh-water and land mollusca which have been 
introduced into the British Islands by human agency—reviewing at 
April 1894. 
