Report of the State Geologist. 



419 



that the fauna of the etage F was not divisible except into different 

 -facies. Frech (1886) made the Bohemian a representative of the 

 Devonian series to the top of the middle division, and F the equiva- 

 lent of the Hercynian as lowest Devonian; in 1887 he placed the base 

 of the Bohemian Devonian at E 2 (Hercynian); Barrois (1889) made the 

 Hercynian, with Beyrich and Kayser (1878, not 1880) a lowest Devo- 

 nian fauna, but differed from Kayser (1878, 1880) in regarding it, not 

 as a calcareous facies of the Spiriferensandstein or Coblenzian, but 

 as such a facies of the older Gedinnian, considering the Bohemian G 

 as its equivalent. 



In our own country the succession of Silurian and Devonian faunas 

 is so unbroken that it would be difficult to conceive of a controversy 

 of this nature taking origin on American soil. The real source 

 of the discussion may be found in the conception held by Barrande 

 in regard to the faunal equivalence expressed in the Bohemian 

 "Silurian" basin. While admitting the homotaxy with the Silurian 

 of Murchison, up as far as the top of the etage E (which was to be 

 regarded as the representative of the Wenlock and Ludlow), he looked 

 upon the extensive faunas of F, and G as Silurian, and records of 

 Silurian life and time not preserved within the upper limits of the 

 Silurian as originally consituted. Were the demands of priority to 

 be insisted upon here, as some writers require, these would necessi- 

 tate drawing the dividing line between Silurian and Devonian at the top 

 of E (assuming that to be the proper equivalent of the English highest 

 Silurian) ; but with these considerations aside (and it is very dubita- 

 ble if historical precedence in defining the secular limitations of 

 faunas can be enforced with any logical exactitude), there can be no 

 question that the F, G, and H faunas were correctly referred to time 

 later than that represented in the classical sections of the Silurian, if 

 these faunas do contain a predominance of Silurian types. Although, in 

 determining such a question, there must always be generous allowance 

 for the personal equation in apprehending the diagnostic values of 

 types, we may accept the now essentially united opinions of the European 

 investigators, that these Bohemian faunas do contain a preponderance 

 of Devonian over Silurian types, and probably, also, that the successive 

 culmination of different Devonian types in successive etages, fur- 

 nishes evidence of equivalence, not merely to one Devonian fauna, 

 but to successive Devonian faunas. 



Though not finding in Europe an equivalent of his F, G, H, Barrande 

 believed one to exist in the distant Upper Helderberg faunas of New 

 York, which he ever regarded as of Upper-Silurian age, and evidence 

 of this correspondence in faunas has been amplified by the studies of 



