60 PREHISTORIC EUROPE. 



There is thus a strong analogy between the deposits at La Celle 

 and Canstadt, as M. Tournouer has pointed out. Their faunas 

 are characterised by the similar proportion of the same elements, 

 and by the presence especially of the extinct Zonites and the 

 Succinea, together with Helix bidens. 



In the Pleistocene fiuviatile deposits of England occur three 

 well-known river-shells, Cyrena fluminalis, Unio littoralis, and 

 Hydrobia (Pahcdina) marginata, which are common also in the 

 beds of the same age in northern France. None of those three 

 species is extinct, but they have all disappeared from the living 

 fauna of Britain. Cyrena fluminalis, indeed, is now no longer 

 a native of Europe, but still lives in the Nile, the Lake of Tibe- 

 rias, and the streams of Cashmere. Unio littoralis is found in 

 the waters of the Seine and the Loire, but Hydrobia marginata 

 has forsaken the rivers of Northern France and retired to those 

 of the south and south-west, and to the Jura and Switzerland. 



We have thus strong testimony furnished by the land- and 

 freshwater-shells as to the former prevalence, during some part 

 of the Pleistocene Period, of a more humid and equable climate 

 than the present ; a climate characterised above all by the mild- 

 ness of its winter. But just as an examination of the old flora 

 has compelled us to admit that the climatic conditions were not 

 continuously genial throughout Pleistocene times, so shall we be 

 led presently to similar conclusions by a study of the mollusca. 



Professor F. Sandberger, who is a well-known authority in 

 the study of land- and freshwater -shells, supplies us with a 

 number of facts, which seem at first to be strongly at variance 

 with the results obtained by MM. Klein and Tournouer. He 

 has recently given an interesting account 1 of certain Pleistocene 

 deposits in the neighbourhood of Wurzburg, in Franconia, from 

 which I take the following list of shells : — 



1. Limneus ti-uncatulus, Mull. ; very rare. Living in Franconia. 

 Europe generally, and Siberia ; in Heligoland it is the only snail. 



1 Verhandl. der physicalisch-medicinischen OesscUclmft in Wurzburg, N. F., 

 Bd. xiv. 1879. 



