278 Canadian Record of Science. 



DlSCUSSIOX OF THE PROBLEM. 



From the foregoing it will be seen that the reference by 

 Mr. Fletcher and Dr. Ells of the Eiversdale-Harrington 

 Hiver and MacKay's Head plant beds to the Hamilton 

 would necessitate the existence of essentially Middle Car- 

 boniferous floras in the Middle Devonian. This could be 

 admitted only on absolutely indisputable stratigraphical 

 evidence, such as their occurrence in a continuous 

 normal section, with abundant characteristic Middle 

 Devonian marine fossils in close association or appropriate 

 sequence. Evidence of this character appears to be wholly 

 absent or quite inconclusive. It does not appear that the 

 testimony of the animal fossils from the plant beds differs 

 widely from that of the plants. The contradictions 

 between the correlations by stratigraphy and those of 

 palteozoologists ^ are perhaps less striking only because the 

 evidence of invertebrate fossils is less abundant or is of a 

 class of animals (e.g. Phyllopoda and Anthracomyse) of 

 somewhat uncertain stratigraphical value. 



The grounds for confidence in the palteobotanical evi- 

 dence are strong. The plant remains on either side of 

 the Lower Carboniferous — i. e. in the Devonian and in the 

 Upper Carboniferous — exhibit the same succession of 

 essentially identical contemporaneous floras in New Bruns- 

 wick and in other regions of Nova Scotia as well as in the 

 United States. This presumptive evidence in favor of the 

 contemporaneity or approximate contemporaneity of the 

 floras of the Lower Carboniferous and Pottsville (Millstone 

 Grit) of the United States and Europe on the one hand 

 with the corresponding floras of the Horton and Rivers- 

 dale ])eds of Nova Scotia on the other hand is supported 

 by the geographical relations as well as the conditions of 

 migration. A land stretch of no very great extent, and at 

 limes reduced to a lowland, between the Nova Scotia and 



1 Dr. Ami jilaces the Riversdale beds within the Carboniferous period, but at the 

 base of the Lower Carboniferous. (See Trans. Nova Scotia Inst. Science, Vol. X., p. 171.) 



