268 C. SCHUCHERT — LOWER HELDERBERG-ORISKANY FORMATIONS 



Upper Coblenz slab tlie equivalent of the Hamilton or Middle Devonic 

 beds. However, the present writer does not mean more than faunal re- 

 semblance, certainly not synchronous equivalence. In any event, the 

 Upper Coblenzian has nothing to do with the Oriskany, but rather with 

 the American Corniferous and Hamilton. These divisions are here re- 

 garded aa members of the American Middle Devonic. 



A very similar result is obtained by examining the plates illustrating 

 11 Die Fauna des Hauptquarzits " of the Hartz, by Kayser * This hori- 

 zon is correlated with the Upper Coblenzian of the Rhine. With very 

 few exceptions the species there illustrated find their nearest relatives in 

 the American Hamilton. A few of'the brachiopods, however, agree best 

 with Corniferous species. 



CONCL USIONS 



If the faunas of the Hercyn (Kayser) and Siegen are the equivalents 

 of the Oriskany. then beds the age of the Lower Helderberg are to be 

 found in the Gedinnian and Taunus, or zone of Spirifer mercuri, in the 

 Rhineland. This fauna, however, is a very small one, and the writer does 

 not feel warranted in making a correlation of value. But the Gedinnian 

 of Germany and France is often correlated with etage F of Bohemia. 

 In any event, the Lower Helderberg has its equivalent in etage F 2 Konie- 

 prussian. It will be shown in the next chapter that the Lower Helder- 

 berg fauna has decided Devonic characteristics and very little of typi- 

 cal, or Murchisonian, Upper Silurian. 



The Hercyn of the Hartz and the Siegen grauwacke of the Rhineland 

 (possibly, also, the Linton slates of the Lower Devonic of England) 

 appear to be equivalents of the Oriskany. Both these faunas have a 

 brachiopod development which unmistakably points to the younger 

 Oriskany, but there is also a facies which finds its nearest expression in 

 America in the older Oriskany. In this connection it may be pointed 

 out that de Verneuil.f after his visit to America, published the view, in 

 1S47, that the Oriskany is Devonic, regarding it as the equivalent of the 

 fossiliferous schists (Spirifer sandstone) of the Rhine. The sediments of 

 the later Oriskany are very coarse, and the older Oriskany is as yet 

 practically unworked paleontologically. Therefore, at present large 

 brachiopods chiefty constitute the known Oriskany fauna. This expres- 

 sion is also seen in the Hercyn and Siegen faunas. On the other hand, 

 the German sediments are less coarse, presenting conditions for a dif- 

 ferent faunal development, while the waters were also probably deeper. 



* Alih. d. k. preuss. geol. Landesanstalt, n. ser., Theil 1, L889. 



t Bull. Sex;. G6ol. de France, 2d ser., vol, iv, 1847, pp. (S4G-709 ; see also Hall's translation, Amur. 

 Jour. Sci., 1848, pp. 177-178, 



