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THE POPULAR SCIENCE MONTHLY 



HiSTOKiCAL Connections of the Geoups of Gymnospekms : 1, Cycadofilicales ; 

 2, Cordaitales ; 3, Bennettitales ; 4, Cycadales ; 5, Ginkgoales ; 6, Conlferales ; 7, 

 Gnetales. 



chiefly from material obtained from the Coal-measures. Although the 

 two groups are equally ancient, so far as our records go, having been 

 recognized well into the Middle Devonian, it is quite evident from com- 

 parative structures that the Cycadofilicales are the more primitive, and 

 presumably the more ancient. Whether they are actually the most an- 

 cient seed plants or not, they are at least the most primitive seed plants 

 of which we have any knowledge. 



The presence of this great group of primitive seed plants (Cycado- 

 filicales) in the Paleozoic was obscured for many years by the impres- 

 sion that they were ferns. A very large percentage of the Coal-measure 



