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from their ordinary states. My own impression is^ that 

 they have not done so ; and, moreover, that, if they 

 had, our catalogues would have worn a very different 

 appearance to what they now do : for, when once the 

 subject is fairly looked iato and analysed, it is impossible 

 not to be convinced, that the primd-facie aspect of these 

 creatures is eminently beneath the control of the several 

 conditions to which they have been long exposed. But 

 let me not be misunderstood ui the conclusion which I 

 have been thus compelled to endorse, or be supposed to 

 ignore the fact that truly representative species may 

 frequently occur Id countries far removed from each 

 other ; which cannot therefore be regarded as modifica- 

 tions of a common type. I believe, however, that this 

 doctrine of representation, whatever truth it may con- 

 tain, has been too much relied upon ; and that we have 

 been over-ready to take advantage of it (unproved as it 

 is) for the multiplication of our, so called, " specific 

 novelties.^' I suspect, indeed, that actual representative 

 species (if they may be thus expressed) are more often 

 to be recognized on the isolated portions of a formerly 

 continuous tract, than in regions which have been widely 

 separated since the last creative epoch ; and that, in the 

 iastances where beiags of a nearly identical aspect are 

 detected iq opposite divisions of the earth, it is more 

 often the case that members of them have been trans- 

 ported at a remote period (either by natural or artificial 

 means) from their primaeval haunts, and have become 

 gradually altered by the circumstances amongst which 



