GEOLOGICAL SPECULATIONS. 



All the others belong to genera still existing in the tor- 

 rid zone. Three of these genera, viz. the rhinoceros, 

 hippopotamus, and elephant, occur only in the old world; 

 the fourth, the tapir, exists only in the new world. But 

 the fossil species have not the same geographical distri- 

 bution : It is in the old world that we dig up the bones 

 of the tapir, and some remains of the elephant have been 

 discovered in the new world. The fossil species includ- 

 ed under the known genera differ sensibly from the 

 present species, and are certainly not mere varieties. Of 

 all the eleven fossil species, the large hippopotamus is the 

 only one which we cannot say with certainty does not 

 belong to the present living species of that genus. The 

 small hippopotamus and gigantic tapir are unquestiona- 

 bly new species ; there is scarcely a doubt of the fossil 

 rhinoceros being a distinct species ; and although the 

 fossil elephant and the little tapir are not so well marked 

 as new species, yet, as Cuvier remarks, there are reasons 

 sufficient to convince the experienced anatomist of their 

 being different from any of the present existing species. 

 These different fossil bones are found almost everywhere 

 in beds of nearly the same kind ; they are often promis- 

 cuously mixed with bones of animals resembling the spe- 

 cies of the present time. These beds are generally allu- 

 vial, either sandy or marly, and always near the earth's 

 surface. It is therefore probable that these bones have 

 been enveloped by the last, or one of the last, catastro- 

 phes to which our earth has been subjected. In many 

 places they are accompanied with accumulations of ma- 

 rine animal remains, and in other places the sand and 

 marl which cover them contain only fresh water shells. 

 Wo have no authentic account of their having been 

 found covered with figetz, or other solid strata contain- 

 ing marine animals, and therefore cannot affirm that 

 they were for a long time covered with a tranquil sea. 



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