139 



Echinospherites Bed. The massive, pure, dove-colored strata of the 

 Stones Eiver limestone are followed in Maryland by dark blue argillaceous 

 cobbly limestone which is never over 50 feet in thickness. In fresh out- 

 crops, such as in the railroad cut at Pin^sburg Station, Maryland, this 

 limestone appears quite massive, but close inspection shows thin, shaly 

 seams dividing the main mass of the rock into dark blue strata. Upon 

 weathering these strata give rise to rounded pieces much resembling cobble 

 stones. This feature is especially characteristic of the Echinospherites 

 bed, although other divisions of the Chambersburg limestone exhibit 

 similar strata. 



This bed contains a few highly fossiliferous bands which have yielded, 

 in Pennsylvania outcrops, a fauna of about 27 species shown in the fol- 

 lowing list published by Ulrich. Of these the ball cystid Echinospherites 

 is the most abundant and its remains may be found at almost every out- 

 crop of the bed. Brachiopods and bryozoans of Black River types are 

 associated with this cystid, although specimens are much less abundant. 



Numerous exposures of this bed occur in the line of outcrop from 

 Pinesburg Station northward through Wilson to the State line, the best 

 places for fossils being in the Western Maryland Railway cut at Pines- 

 burg Station and the bluffs overlooking Conococheague Creek at Wilson. 

 In southern Pennsylvania excellent exposures of this bed are found in the 

 railroad cut at Kauffman and one mile northwest. Excepting the charac- 

 teristic fossil Echinospherites, the fauna of this bed seems most closely 

 allied to the upper Black River Decorah shale of the Mississippi Valley 

 and for this reason its age is placed as late Black River. The species in 

 the following list marked with an asterisk have been found in Maryland : 



Fauna of the Echinospherites Bed, Chambersburg Limestone 



Licrophycus cf. L. ottawaense 



Lockeia sp. 



*Receptaculites occidentalis Salter 



Ischadites sp. 



Orocystites ? sp. 



tiapJianocrinus ? sp. 



*Echinosphcrites aurantium americanum Bassler 



*Helopora spiniformis Ulrich 



