AND LOWER EGYPT. I75 



Gmelin has not then committed a mistake, in 

 describing what he saw, and which, conformably 

 to the more modern observations which you, Sir, 

 produce, he must have seen in the countries which 

 he traversed. On the other hand, it is inconsistent 

 with good logic to impute error to him, when all 

 that can be alleged against him amounts to one or 

 two negative proofs, which are totally insufficient 

 to annihilate one single positive proof. It has ap- 

 peared to me, for some years past, that travellers 

 and naturalists indulged themselves rather too 

 lightly in contradicting their predecessors. This 

 is not the place to examine whether science has 

 gained much from this general tone of criticism ; 

 but it has induced me to insist on M. Gmelin's 

 justification, independent of its connexion with 

 my own. In truth, on the supposition that this 

 observer had carried imposition so far as to paint 

 a quadruped, the forms of which were not such as 

 he had ascribed to it, we should not be the less 

 warranted to affirm that the jerbo of Egypt has a 

 very striking resemblance to another gerboise de- 

 scribed in the Commentaries of the Academy of 

 Petersburgh, under the denomination of alagtaga ; 

 this is all I pretended to say, without presuming 

 to pronounce respecting its reality, any more than 

 respecting the degree of confidence to be granted 

 to the traveller who had described it. 



The 



