370 



so kind as to send me. They were very interesting to our Geological 

 Society (of France) where I showed them, stating that this species is 

 identical with P. spinosus of Bohemia. This is a very important fact, and 

 should have a happy result, that of establishing the relative age of the 

 most ancient formations on the two continents." 



In his note " On the Primordial Fauna^'' (see " Bui. de la Soc. 

 Geol. de France,^' vol. XVII. p. 551,) M. Barrande gives it as his 

 opinion that the P. Bennetti, though differing, from the P. spinosus 

 of Bohemia, belongs to the same group of fossils. 



This being established, let us proceed a little farther and see 

 if previous discoveries and published records permit the exten- 

 sion of the Primordial fauna over some other portions of North 

 America. 



Prof E. Emmons in his geological survey of Lake Champlain, 

 as far back as 1838, recognized below the Potsdam sandstone a 

 series of strata, which he described at length in 1844, and named 

 the Taconic System. The fossils then found by Prof. Emmons 

 were few in number and so badly preserved that some doubts 

 may have been entertained at that time as to their determination 

 and value as characteristic fossils. Nevertheless, his Eliptocepha- 

 lus asaphoides was a Trilobite form so different from those known 

 in the other strata of New York, that a skilful paleontologist would 

 not have let it pass without further inquiry. 



The principal argument of Prof. Emmons was based on strati- 

 graphical and lithological grounds, and the numerous sections 

 and descriptions of rocks accompanying his Taconic system are 

 certainly conclusive, so far as geognostical characters are con- 

 cerned. The paleontologist of the State of New York rejected 

 the Taconic system, and, siding with other opponents of Prof. Em- 

 mons's discovery, in his first volume of the '' Paleontology of New 

 York," (1847,) Mr. James Hall assigns the age of the Hudson 

 River group to the strata of the Taconic system, explaining the 

 difference of lithological characters by metamorphisms, the dis- 

 cordance of stratification and the different thickness of the strata 

 by folding and faults ; the fossils he regards as badly determined. 

 His opinions are not supported by detailed sections, but he refers 

 to the Introduction of his work for explanation, which Introduction 

 as yet remains unpublished. 



