FOSSIL BATS 309 



camp horses. Thus was set at rest forever the long vexed question as to which 

 was the true blood-sucking vampire. It may be observed, however, that whereas 

 it is now certain that the present group is the only one of which the members sub- 

 sist entirely on a diet of blood, yet it is possible that, as already mentioned, some 

 of the javelin-bats or their allies, may, on occasions, vary their ordinary food 

 with it. 



FOSSIL BATS 



From the exigencies of space our account of the bats has been somewhat brief ; 

 but it may serve to show what an extensive assemblage of animals it really in- 

 cludes, and how different from one another in habits, as well as in details of 

 structure, are many of its members, though all bats agree very closely in their 

 general plan. This conformity to a common structural standard is as fully charac- 

 teristic of the few fossil bats with which we are at present acquainted, as it is of 

 their modern allies ; the whole of them belonging to living families, and a large 

 proportion to existing genera. At the comparatively early period when the Upper 

 Eocene strata of the Paris basin were deposited, leaf -nosed bats, as well as typical 

 bats nearly allied to the living noctule, had already come into existence, and have 

 left their remains buried in the rocks alongside those of strange extinct hoofed 

 Mammals, such as the Palseotheres and Anoplotheres. And it is, therefore mani- 

 fest that if we ever succeed in discovering the ancestral forms from which bats have 

 been derived, it will be in rocks of far greater age than those of the Paris basin, 

 which belong to the lower portion of the Teritary period of geological history. It 

 is, indeed, within the bounds of probability that bats have existed as such from a 

 period as remote as the one during which the English chalk was deposited on the 

 floor of an ancient ocean. 



