THE MAGAZINE 



OF 



NATURAL HISTORY 



FEBRUARY, 1840. 



Art/ I. — View of the Fauna of Brazil, anterior to the last Geo- 

 logical Revolution. By Dr. Lund. 



(Continued from Page 8). 



The greater proportion of these caves have their entrances so 

 disposed, that rain-water penetrates into them, either in the 

 shape of casual or periodical floods, or else in that of con- 

 stant streams. This water has often no other outlet than 

 the fissures in the floor of the cave; but it not unfre- 

 quently pursues its course quite through, and escapes by an- 

 other aperture. The rain-water necessarily brings with it soil 

 and organic remains, which it is highly necessary to distin- 

 guish from the older deposits of the same kind ; and fortu- 

 nately this is no very difficult point. The dry bed of former 

 floods is often so distinguishable that it cannot easily escape 

 notice. A channel, often so deep in the soil as to expose the 

 rock, and strewed with sand and boulders, admits of no 

 doubt ; and in it besides are often found shells of recent Mol- 

 lusca, branches, roots, and leaves of trees, &c. 



When this proof is wanting, the condition and contents of 

 the soil itself will serve to characterize it. Should it be loose 

 and light, of a grey or black colour; — or if it contain the 

 slightest trace of vegetable remains, uncarbonized ; — then 

 there can be no doubt of its recent origin, even in the rare 

 contingency of our not being able to discover the passage by 

 which it has entered, which is usually easy enough to per- 

 ceive. Where these distinguishing marks are all absent, the 

 determination becomes more difficult. In some caverns I 

 have seen alluvial deposits in which no trace of vegetable re- 

 mains could be detected, and which notwithstanding, if they 

 have not been introduced at late periods by water, have at 



Vol. IV.— No. 38. n. s. h 



