314 VIEW OF THE FAUNA OF BRAZIL 



cies in the genus Mus of that former period, from which I 

 deduced the conclusion that we have no ground for beheving 

 this number to have been in reality less than it now is. The 

 fossils of this family are found under the same conditions as 

 those of the rodents ; the bones of the smaller kinds entering 

 into the composition of the fine osseous breccia, while those 

 of the larger species are intermixed with the bones of those 

 animals that have constituted the food of the beasts of prey.' 



Family of Bats, 



All the families we have hitherto considered, have either 

 exhibited to us a greater abundance both of genera and spe- 

 cies, in the former than in the present period, or have at least 

 allowed room for the supposition that they were not inferior 

 in this respect. It is otherwise with the family we now pro- 

 ceed to examine. Notwithstanding the most careful search, 

 I have not yet been able to discover the least trace of any 

 animal of this family in the sediment of the last great deluge 

 in this district ; and, as far as my information extends, the in- 

 vestigations of scientific men in the old world have been 

 equally unsuccessful. We might thus seem authorized to 

 conclude, that this family was really wanting in the pre- 

 existent fauna. I must, however, draw attention to several 

 circumstances that show the necessity of caution, before we 

 come to a positive decision on this point. Of all mammals, bats 

 are the least exposed to the attacks of predatory beasts ; and 

 we therefore could hardly expect to meet with their remains 

 among those of the animals that have served for their food. 

 It would, on the other hand, appear probable that they should 

 be the prey of owls, through whose instrumentality many of 

 the other bones have been introduced into our caves. 

 I have, however, shown, in my former communication, how 

 very small a quotient (only 1 per cent.) their bones consti- 

 tute in the composition of these heaps. If to these consi- 

 derations we add the fact that this family has left traces of its 

 existence in a still more ancient period of the world, in the 

 gypsum of Montmartre, we surely see that we must not, with- 

 out a very strong amount of proof, agree to so extraordinary 

 a result, as such an alternating appearance, disappearance, 



» I possess a molar tooth of a large animal, which differs in its form 

 from the molars of all predaceous animals, and most nearly approaches 

 the hindmost teeth of Didelphis. Until I am fortunate enough lo obtain 

 more fragments of this remarkable animal, I abstain from guessing at its 

 proper place in the system. The tooth seems to belong to an animal of 

 the size of a large wolf. 



