BIELBECKS. 
151 
balance of opinion ; and geologists were not justified in coming to a 
positive conclusion. But the occurrence with the elephant and rhinoceros, 
of thirteen species of land and fresh- water shells precisely identical with 
existing types from the neighbouring pools and ditches, must he allowed 
to give more exact and satisfactory evidence. Such a group of mol- 
luscous animals, does not exist together except in a small range of 
latitude, to the north or south of England. Before arriving at the 
parallel of 60° N. many of the species are lost ; others vanish and are 
replaced by new forms before we touch the shores of the Mediterranean ; 
such then are the limits within which speculations as to the ancient 
climate of the northern regions once tenanted by the elephant and 
rhinoceros, must be restrained ; and those who recollect the hairy cover- 
ing of the individuals of these genera found on the shores of the Arctic 
Sea, will probably supply for themselves the obvious conclusion, that 
these animals were fitted by a peculiarity of constitution to support at 
least tlie occasional rigours of a temperate climate. 
Existing species of fresh-water shells, occurring in connexion with 
extinct fossil quadrupeds, have been noticed by Mr. Hugh E. Strick- 
land, under beds of gravel near Cropthorne in Worcestershire ; they 
occur abundantly in an ancient lacustrine deposit near Weimar, and it 
is probable that future research will greatly augment the mass of facts 
bearing on this subject. The ossiferous deposits in Val d’Arno may 
perhaps belong to this period. 
