OF THE ORGANIC 1 FOSSILS. 445 



shown the difficulty of determining the marine or 

 terrestrial origin of fossil fishes. As to the other 

 error, all strata were formerly thought to he of marine 

 origin : and thus were all fishes, in partieular, formerly 

 supposed to be of the same nature; whenee, if found 

 accompanying terrestrial remains, transportation was 

 inferred, under either or both errors. And recent 

 observations have not been free of the same mistakes 

 and the same false inferences. The "bituminous marl 

 slate" was an error of the former kind, of the Freyberg 

 school: the supposed marine stratum is a fresh water 

 one. At Claris in Switzerland, ferns occur with 

 fishes, and the latter must therefore belong to fresh 

 water. Former observations had determined that 

 marine and fresh water fishes existed with vegetables in 

 the strata of CEningen, and thus were formed false and 

 impossible theories respecting this deposit. If I am 

 right respecting the versatility of fishes, the fact as 

 to some of these species may still be true, or there 

 may be marine fishes in these strata: the very Triglae 

 quoted may exist in it, though the specimens seemed 

 to me more than doubtful ; and yet this deposit is but 

 a part of the antient bed of the lake of Constance. 

 And this illustrates the other source of error. 



I may therefore conclude. There is no proof of trans- 

 ported fossils, under any other circumstances, or from 

 any other causes, than those which I have explained; 

 and I hope that I have shown how these can be distin- 

 guished. But the distinction demands acute geo- 

 graphical observation, even more than geological 

 knowledge ; and hre have observers especially failed. 

 Of the Mosaic deluge in particular, I have no hesi- 

 tation in saying, that it has never been proved to 

 have produced a single existing appearance of any kind, 



