122 THE ZOOLOGIST. 
present. During the subsequent glacial epoch the whole of the 
British islands, including portions since submerged, were clothed 
in an eternal winter mantle, partly snow and partly in the form of 
glaciers, which moved down from the high to the low lands, 
carrying with them rocks and débris of all kinds to form fresh 
deposits. 
The remains of the animals in question have been preserved 
chiefly in caves or in river deposits. The limestone caverns, in 
which they are found, usually present the following appearances :— 
On the floor there is a bed of calcareous drippings hardened into 
a substance known as stalagmite. Under the latter may be seen 
successive layers of clay and stalagmite of various thickness. Some- 
times the osseous remains are found on the floor of the rock simply 
embedded in the stalagmite. The various levels formed by an alter- 
nation of cave-earth or clay and drippings may represent various 
stages in the history of a cave. For instance, on the surface flint 
tools, fashioned by man, together with bones of the Red Deer and 
Oxen, may be found; in the second layer may be discovered the 
remains of herbivorous quadrupeds and of Lions and Elephants, 
the larger bones showing evident traces of having been gnawed by 
predaceous animals. Under these conditions, it may be surmised 
that the cave was originally a den of carnivorous animals, which 
had dragged in the bones of their prey, until the surface, getting 
gradually covered over by stalagmitic drippings, became eventually 
the resort of man. Of course the absence of traces of his presence 
is no proof that he may not have been contemporary with the lions 
in the second deposit; at the same time, we are not justified in 
admitting his presence unless we find the bones of domestic animals, 
flint tools, or other relics of man mingled in the same stratum. As 
to the age of these two deposits, they may or may not represent long 
periods; much depends on the rapidity or otherwise of the influx 
of the cave-earth, either through rock-fissures or by the aid of 
streams, which convey large quantities of soil into underground 
caverns; whilst the extent of dripping of the lime-water from the 
roof and sides, and its hardening, depend entirely on circumstances ; 
for a cave may get filled to the top in a comparatively short time, 
or its filling may be the work of ages. In either case some covering 
of the bones must take place before they have time to decay, as 
they otherwise would do if left uncovered. It is wonderful how 
little stalagmite is required to preserve a bone; a mere crust, not 
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