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■fiance bears to the many difcoverics that have been made, not 

 only of fliells but of horns, teeth, bones, and otiier remains, 

 and even of entire fkeletons, of various land-animals, partly 

 known and partly tmknown, in countries where fimilar living 

 fpecies have never been obferved to exift, and often in cli- 

 mates now wholly unfuitcd to their conftitutions. Thele extra- 

 ordinary facls have been long known, and have long excited 

 the attention, and exercifed the ingenuity, of naturalifts of the 

 moft diftinguiflied talents : But, unfortunately, experience has 

 fliewn that the paths of fpeculation to which they dirctftly lead 

 have too often condudted thefe great men into labyrinths, from 

 which all the efforts of their genius have not been able to 

 extricate them. Hence it would feem, that natural knowledge 

 is not yet fufficiently advanced, nor a fufEcient flock of well- 

 attefted phenomena yet formed, to enable us to profecute fuch 

 extenfive and difficult enquiries with good effedl. On this ac- 

 count, perhaps, thofe who really wifh to contribute to the 

 fubftantial improvement of the fcience, might employ their 

 talents more beneficially, in the humble tafk of colledling fads, 

 and invefligating partial and immediate caufes, than in giving 

 the reins to their imaginations, and foaring in purfuit of vifi- 

 onary theories. Of more remote and general caufes, poflerity, 

 better informed by new fadls and obfervations, in addition to 

 thofe which we now poffefs, may poffibly form a better judgment 

 than we can afplre to, if fuch a judgment really lies within the 

 limits of human attainable knowledge. But, at all events, it fliould 

 not be forgotten, that fpeculations of this kind are regarded by 

 iTicn of the foundeft unJerflaudings, rather as amufements of the 



mind, 



