PREVIOUS TO THE LAST GEOLOGICAL REVOLUTION. 53 



witness of the fact, the multitudes in which they are found in 

 certain caverns, must seem perfectly incredible. There are 

 caverns, commonly called '' Lappas dos Morcegos," that is, 

 bat-caverns, which are rendered almost impassable by these 

 creatures. Their liquid excrement covers considerable sur- 

 faces of the walls and floor, rendering the latter so slippery 

 that it is hardly safe to cross it where at all inclined; and 

 besides, the strong ammoniacal odour exhaled is enough to 

 stifle the intruder whom science has lured into these murky 

 labyrinths. I have seen considerable spaces of the roof so 

 thickly covered with bats, that they appeared matted toge- 

 ther ; and when disturbed, the universal flutter agitates the 

 air so much as to extinguish the lights. Nor is it only in the 

 living state that they are found, but dead or dying they are 

 also seen hanging from the roof by their hind legs ; while 

 their remains are strewed over the floor in every stage of de- 

 composition. 



In these caves I have discovered some species of the ge- 

 nera Phyllostoma, Molossus, Glossophaga, Vespertilio, and 

 others ; but the most abundant by far is a new geims, which, 

 from its peculiar dental system, is not only far removed from 

 the other genera of this family, but even stands alone in the 

 order Mammalia. Of this very remarkable creature I hope 

 soon to forward a description and drawings. 



As the bats hold the first place among the living inhabit- 

 ants of these caves, so is it the family of rodents which have 

 left the greatest number of recent bones there. And as the 

 bones of the Rodentia form no inconsiderable portion of the 

 fossil remains ; — and the species of this family at present ex- 

 isting in these parts being besides very imperfectly known ; 

 — it will be advisable to offer a short sketch of them : pre- 

 mising that in their enumeration, as well as in that of all 

 others that may follow, I strictly confine myself to those 

 which, either from my own observation, or from the reports of 

 trustworthy witnesses, I know to be inhabitants of the dis- 

 trict in which these caverns are situated. * 



' Brazil embrace?, witliin its extensive boundaries, great varieties of cli- 

 mate and other physical conditions. In the southern provinces, most of 

 the tropical forms, both of animals and vegetables, disappear, and are re- 

 placed by new ones. There is scarcely less difference observable in com- 

 paring the interior highlands with the narrow tract which extends along 

 the coast, and is bounded by a high, wooded, wall of rock. Fortius reason 

 I have not been able to confine myself to mere political divisions. And be- 

 sides, as it is an indubitable truth that the extinct animals have in general 

 lived in the spots where their remains are now found, a geographical com- 

 parison of existing and extinct animals must necessarily be confined to the 

 district where the latter occur. 



H 3 



