82 THE DEVONIAN AND CARBONIFEROUS. [bull. 80. 



Bussian Permian, the problem of correlation is definite. Both the 

 stratigraphy and the biological evidence indicate that there is no sharp 

 division between the representative of the Pennine Carboniferous sys- 

 tem and that of the Permian system. The division line here must be 

 arbitrarily drawn, and the fact that a system is a local series of forma- 

 tions, and not a universal subdivision of the geologic time scale, be- 

 comes evident. It is in such cases that the paramount importance of 

 the determination of the geographic position of the typical representa- 

 tive of a system is seen, and the only way to make this apparent to all 

 is by all the association of the geographic name with the system. 



