98 



The Middle Devonian Deposits of Maryland 



]/(orhijnclnis lim.Hare and L. iiiijsid are especially diagnostic of the Mar- 

 cellns. 



Lithologically the sediments closely resemble the Marcellus shale of 

 New York, consisting chiefly of dark or black, carbonaceous, fissile shale. 

 Tliin beds of limestone are also present as in the corresponding formation 

 in New York, altlioiigh this is a less conspicuous feature in the deposits 

 of Maryland. These facts fullv establish the ]\[arcellus age of the beds. 



The age of the blue fissile shales that lie between the strata containing 

 the Marcellus fauna and the beds carrying the Hamilton fauna is open 

 to question, no fossils having been observed in them up to the present. 



Marcellus Species 



3 



s 



a 







a 



as 

 W 



a 



C 



O 



1 



u 



o 



BRACHIOPODA 



Auibocoeli a vii'Kiniana Prosser 





+ 

 + 



+ 

 + 



+ 

 + 





Stroplialosia truncata (Hall) 



+ 



+ 

 + 

 + 



+ 

 + 



+ 





Camarotoecliia prolifica Hall 





Liorlivnchns li raitare ( Vanuxem) 





Liorliynchus cf. mysia Hall 





PELECYFODA 



Buchiola restrostriata (Von Buch) 



+ 



Nuciila corbulifoimis Hall 



+ 



PTEUOPODA 



Styliolina fissureUa (Hall) 



+ 







Prosser has included them in the Hamilton memlier, while Kindle refers 

 them to the Marcellus member. Lithologically they probably resemble 

 the ]\Iarcellus beds more closely than they do the overlying Hamilton 

 shale which, in general, is not fissile, but blocky, and breaks into irregu- 

 hiT, many-sided fragments. 



Hamilton lilEMBER * 



The rocks overlying the Marcellus shale of the Romnev formation and 

 extending northeasterly from northern West Virginia across Maryland 

 and Pennsylvania to New York have been much more frequently corre- 



' Contributed by Charles S. Prosser. 



