50 VIEW OF THE FAUNA OF BRAZIL 



least been exposed to its influence. The characters most to 

 be depended on in the latter case, are a very pale dull colour, 

 approaching to ashen-grey; a greater intermixture of sand 

 than usual on the surface, with a diminution in the quantity 

 downwards ; the presence of rolled stones lying loose on the 

 surface ; the absence of saltpetre, and of the stalagmitic coat- 

 ing: — these signs are sufficient to prove that rain-water has 

 gained admission into the caverns, and operated on the soil 

 therein, though it may not have originally deposited the latter. 

 Caverns of this description demand the most careful examina- 

 tion ; for not only might recent bones be covered with soil 

 deposited by the water in its passage, but also, really ancient 

 fossils, which had previously lain in the soil, might be washed 

 out by the same agency, and deposited in places where their 

 origin and age might easily be mistaken. I have seen exam- 

 ples of both these cases ; but I must confess that the great 

 majority of caverns here, present no such difficulties, but in 

 general have a single opening in the perpendicular, naked 

 face of a rock, high above the sunounding soil, and most fre- 

 quently protected by a projecting roof of limestone. A layer 

 of reddish stalagmite is spread, like a carpet, over the soil of 

 the cavern, and serves to mark the boundary between the past 

 and the present. None of nature's devastating forces have 

 here had place ; all lies undisturbed, and in the same condi- 

 tion as when deposited by that mighty catastrophe which 

 closed the curtain over a former world and its inhabitants. — 

 Such is the theatre to which I wish to introduce the reader ; 

 for what this mantle covers — what this soil contains, belongs 

 without exception to that extinct world. 



The nature and condition of the fossils themselves often 

 afford still better means of determining their age. -In by far 

 the greater number of instances they present the following 

 appearances. The bones are entire and uninjured, with their 

 smallest processes and their finest points and edges well pre- 

 served. Their exterior is of a beautiful reddish ochre-yellow, 

 and their fractured interior of the purest white. They are much 

 lighter than recent bones, and so extremely brittle as to crum- 

 ble to pieces if carelessly handled : they adhere closely to the 

 tongue : if exposed to the action of fire, they turn black, and 

 give out, although in a slight degree, a burnt and fetid odour. 

 A portion of the soil in which they have lain always adheres 

 to these bones, either in the form of a fine dust or coating, or 

 as filling up their cavities. When the enveloping soil has been 

 saturated with lime-water, it adheres so closely to the bone 

 that it is impossible to separate the two. More rarely the bones, 

 without losing their uninjured surface, or the pure white co- 



