STATE GEOLOGIST 81 



should yield to his judgment. But the shells in question seem 

 to my eyes to belong to Clymenia, and I ean do nothing but 

 regard them as such until I am convicted or positively con- 

 tradicted. 



I cannot doubt that the palaeontological characters and strat- 

 igraphical position of the Marshall sandstone place it conclu- 

 sively above the horizon of the Hamilton Group; and hence I 

 am not surprised that none of the nine species of Goniatites 

 described by Prof. Hall, and referred by him to the Hamilton 

 Group, bear any considerable resemblance to the Michigan 

 fossils under consideration. 



From this group were collected, at Battle Creek, the speci- 

 mens described by R. P. Stevens,* as Leda dens- j mammillata, 

 L. nuculceformis, L. pandorceformis, Nucula Houghtoni and 

 Ohonetes Michiganensis. Not one of the Lamellibranchs has 

 been satisfactorily identified by me, amongst the fossils collect- 

 ed at the same locality. The Nuculoid shells have not the 

 pallial sinus nor posterior elongation required by their assign- 

 ment to the genus Leda; nor, supposing them true Nuculce, do 

 I find their specific characters clearly indicated. Moreover, Dr. 

 Stevens' reference of these fossils to " ochreous shales, belong- 

 ing to the coal measures," because " associated with an Ortho- 

 ceras, a Nau'.ilus and Bellerophon Urei, which is evidently carbon- 

 iferous,'' must undoubtedly be regarded as an oversight. The oc- 

 currence of Glymenia in these rocks establishes their Devonian 

 age, while the Bellerophon supposed to be the one referred to, is 

 quitedistinct from B. Urei of Fleming, which is a dorsally sulca- 

 ted shell, while ours presents no trace of such a character. Still 

 further, B. Urei, even if occurring here, would not identify 

 these roeks with the " coal measures," since the range of this 

 species is from the Upper Silurian to the Mountain Limestone. 



The general aspect of the fauna of the Marshall Group bears 

 some resemblance to that repiesented by the figures of the 

 fossil remains of the Rhenish Provinces of Nassau,f in Ger- 



*Sffliman>s Journal, Vol. XXV, [2] p. 262. 



|Seo Sandberger's Systematische Beschreibung und Abbildung der Versteinerungen dee 

 Kheinischen Schichteusystenis in Nassau. 



