414 Forty-second Report on the State Museum. 



Kayser's reason (invalidated by Novak) for drawing the line 

 between Silurian and Devonian in Bohemia through the etage F, lay 

 principally in the absence of Goniatites in F r Frech would regard 

 this as indicating a divergence in facies and compared it to the state 

 of affairs frequently apparent in the Eifel; for example, the essential 

 absence of Goniatites in the Galceola beds, and their great abundance 

 in the Wissenbach slates, formations and faunas substantially equivalent. 

 Upon other fauual grounds, the speaker found in F x a conspicuous 

 divergence from the normal Upper-Silurian in the absence of the 

 trilobite genera Ampyx, Gromus, Deiphon, Staurocephalus, Sphcerexochus 

 and in the extremely meager representation of Galymene; further- 

 more a relatively very small per-centage of species are common 

 to E and F, while a greater number pass through from F to G-. The 

 base of the Devonian is, therefore, placed at F, in accordance with the 

 original conception of Beteich and Kayser. Dr. Frech then called 

 attention to the Tentacuhte layers of the zone G 2 , and compares them 

 with the Tentaculiten Seliiefer of Thuringia and Nassau, considering 

 the latter as lowest Middle-Devonian (in accordance with Kayser's 

 determination) and supporting the comparison and equivalence by the 

 identification of Strophomena comitans, Barrande (G 2 ) with S. subtrans- 

 versa Schnur, of the Eifel Middle-Devonian. Evidence of more deci- 

 sive import in regard to the equivalence of G 3 is adduced from the 

 character of the Goniatite facies. Of these fossils, four species are 

 common to G 8 and the Orthoeeras Schiefer of the Rhine (lowest Middle- 

 Devonian, according to Kayser; uppermost Lower-Devonian accord- 

 ing to Koch and Maurer). Frech also regarded the species described 

 by Barraxde as a lamellibranch under the name Zdimir solus as hardly 

 to be distinguished from Uncites gryvhus. The value of this com- 

 parison, however, falls to the ground from the subsequent determina- 

 tion by Novak * that this fossil is a Pentamerus, and it appears to be of 

 the peculiar, elongate, strongly-ribbed type characterizing the Niagara 

 species. P. laqueatus, Conrad. 



Fre- h's subdivision of the Upper Bohemian then took this 

 expression: 



- = Middle-Devonian. 



G, J 



G- g =? Middle-Devonian. 

 F,> = Lower-Devonian. 

 E 2 = Upper-Silurian. 



* Zeitsckr. d. deutsch. geolog. Gesellseh. Vol. XL. Heft, 3, p. 588, 1888. 



