1869.]
DAWKINS—BRITISH POSTGLACIAL MAMMALS.
217
Mr. W. Boyd Dawkins, in reply, admitted that possibly some animals classed as Postglacial belonged also to the Glacial period; but for convenience' sake he had adopted the three divisions in the paper. He saw no necessity for any of the animals being of purely southern origin. He did not identify the Lower Brick-earth of the Thames valley with the other river-deposits, though, from the presence of the Musk-sheep, he was inclined to place them later than at one time he did. The only reason he could give for the absence of Preglacial caves both in England and on the Continent was, that the rocks containing them may have been removed by denudation.
