FOSSIL MAMMALIA. 97 



Old World. The fifth, that of the tapirs, is the only one 

 existing in the two continents at the present day. It is only 

 in the old continent that the bones of the tapir, the rhinoceros, 

 and hippopotamus have been found. In the new have been 

 discovered some bones of the elephant ; the mastodon, in one 

 species, is common to both. 



The species belonging to known genera are distinct from the 

 existing species, and cannot be considered as simple varieties. 

 This point is beyond the shadow of a doubt, as regards the 

 little hippopotamus, the little rhinoceros, the rhinoceros with 

 partitioned nostrils, and the gigantic tapir. It is not quite so 

 obvious in the case of the elephant and the other rhinoceros, 

 but there are more than sufficient reasons to convince the ex- 

 perienced anatomist of the fact. The same conclusion must 

 be extended to the great fossil hippopotamus, and, by analogy, 

 to the fossil horses, although their remains have not yet fur- 

 nished the clearest evidence of specific distinction. 



Such may be considered the osteological result of the re- 

 searches that have been made on the fossil pachydermata ; the 

 geological consequences are these : — 



The different remains of which we have been treating, are all 

 embedded in depositions nearly similar. They are often found 

 in company with the bones of other animals pretty similar to 

 those which exist at present. These depositions are, for the 

 most part, loose and incompact, whether composed of sandy 

 or marly substances, and always more or less approximating to 

 the surface of the soil. 



It seems probable from this, that these bones were enveloped 

 by the last, or one of the latest, revolutions of this globe. 



In a very great number of situations they are accompanied 

 with the accumulated debris of marine animals ; in others 

 these debris are wanting, and, in some places, the sand or 

 marl enveloping the bones contains only fresh-water shells. 



It does not appear, from any account worthy of the slightest 

 credence, that they are ever covered by the regular rocky 



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