286 GEOLOGICAL CONTEMPORANEITY ix 



be synchronous or strictly contemporaneous ; and 

 there are multitudes of accessory circumstances 

 which may fully justify the assumption of such 

 synchrony. But the moment the geologist has 

 to deal with large areas, or with completely 

 separated deposits, the mischief of confounding 

 that " homotaxis " or " similarity of arrangement," 

 which can be demonstrated, with " synchrony " or 

 "identity of date," for which there is not a 

 shadow of proof, under the one common term 

 of " contemporaneity " becomes incalculable, and 

 proves the constant source of gratuitous specu- 

 lations. 



For anything that geology or palaeontology are 

 able to show to the contrary, a Devonian fauna 

 and flora in the British Islands may have been 

 contemporaneous with Silurian life in North 

 America, and with a Carboniferous fauna and flora 

 in Africa. Geographical provinces and zones may 

 have been as distinctly marked in the Palaeozoic 

 epoch as at present, and those seemingly sudden 

 appearances of new genera and species, which we 

 ascribe to new creation, may be simple results of 

 migration. 



It may be so; it may be otherwise. In the 

 present condition of our knowledge and of our 

 methods, one verdict "not proven, and not 

 provable" must be recorded against all the 

 grand hypotheses of the palaeontologist respecting 

 the general succession of life on the globe. The 



