306 BATS. 



During the daytime these bats repose in caves or hollow trees, whence they 

 issue forth for their nightly blood-sucking. It appears that when they have 

 selected a victim for attack, they either settle down on or hover over the part 

 to be operated on ; and then proceed to shave away a thin portion of skin by a 

 razor-like action of the sharp upper incisor teeth, by which the blood is caused to 

 ooze from a number of the small capillary vessels, and is then sucked up by the 

 mouth and swallowed. From their structure, it is probable that blood constitutes 

 their whole diet. 



The fact that certain bats in South America were veritable blood-suckers 

 has been long known ; our first information dating from a period soon after the 

 conquest of that country. Great uncertainty prevailed, however, for a lengthened 

 period as to which particular species of the large family of vampires w r ere the 

 real culprits ; and the question was not finally decided till, during the voyage of 

 the " Beagle," Mr. Darwin had the good fortune to see a desmodus caught in the 

 very act. His account has been quoted over and over again, almost ad nauseam, 

 and we shall refrain from repeating it here ; merely mentioning that the bat in 

 question which was the common blood -sucking vampire was caught by one 

 of the great naturalist's servants actually sucking the blood from the withers 

 of one of the camp horses. Thus was set at rest for ever 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 subsist 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 

 includes, 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 

 characteristic 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 Palaeotheres and Anoplotheres. And it is, there- 

 fore, manifest 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 Tertiary 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. 



