REPORT OP THE STATE PALEONTOLOGIST 1901 663 



the north, the Levis channel on the east, the Chazy bay on the 

 west side of the Quebec barrier. Though the Chazj bay ex- 

 tended some distance up the Ottawa vaHe^-, there was no com- 

 munication between the Atlantic and Mississippian seas at this 

 time, a great land area to the west of the bay atfording effectual 

 separation. 



Communication between the Atlantic and the Mississippian 

 seas occurred at least once besides the Normans kill, Utica, and 

 Bevonic connections just mentioned. We refer to the communi- 

 cation that probably began during late Upi^er Cambric and 

 either continued through or was revived during Beekmantown 

 time. 



Basis for more exact faunal and phyletic studies. We have pointed 

 out the Paleozoic periods when the Atlantic and .Mississippian 

 seas were separated from each other and also when they were in 

 communication. The relations of the Mississippian sea to the 

 Arctic, northern Pacific and Gulf of Mexico remain in great part 

 yet to be determined. Reliable data are difficult to secure, yet 

 they are not so few as to discourage the hope of ultimate suc- 

 cess. When the more essential facts are known, paleontologists 

 will learn to discriminate between the foreign and indigenous 

 elements of our fossil faunas, and incidentally these new facts 

 will throw much light on general geology and organic evolution. 

 They will not then be so likely to arrange heterogenous specific 

 elements as members of one line of descent, nor will they be 

 so eager to identify or throw together species and genera that 

 better and fuller information may prove to represent even dif- 

 ferent lines of development. The species and genera may have 

 much in common, but the investigator will pause and look care- 

 fully into their derivation, both biologic and geographic, before 

 he will feel justified in pronouncing them identical. In short, 

 we shall secure more critical, and therefore more reliable results, 

 and these will bear sound fruit, not only in the domain of pure 

 biology, but also in stratigraphic geology. The farther we pro- 

 gress along the lines indicated, the more exact will our corre- 

 lations become. Indeed, even extra-continental correlations are 

 not beyond approximate exactitude. 



