and South Central Pennsylvania. 427 



and other fossils. (Parastrophia hemiplicata 

 occurs in this zone at Rathbone Brook, New Port, 

 New York State. Fide T. C. White) 20 feet 



b. Thin-bedded, dark limestone with some inter- 

 bedded, coarse-grained layers. Cryptolithus tes- 

 sellatus the characteristic fossil. Trematis 

 terminalis, Platystrophia trentonensis, Calymene 

 senaria and many other fossils present 41 " 



a. Thin-bedded, grey limestone with an abundance of 



Dalmanella rogata, and some other fossils 32 ' ' 



346 feet 



The 400 feet of the Co-burn compare very favorably 

 with the 155 feet (beds c to e, inclusive) of Raymond's 

 section. Since beds f and g are characterized by R. del- 

 toidea, which fossil is absent in the Coburn, it appears 

 as if the shale deposition began earlier in the Pennsyl- 

 vanian province. The lower 72 feet of the New York 

 section (lower Trenton) differ from the Salona in 

 lithology and also in the absence of Brongiartiella tren*- 

 tonensis. The lower Trenton of Kentucky as described 

 by Ulrich (op. cit., p. 1) may be summarized as follows: 



Hermitage formation. — Thinly-bedded to medium-bedded, fine- 

 grained to granular limestone and shale 50 feet. 



Thin, evenly bedded, argillaceous and 

 siliceous, blue layers of limestone, separated by seams of 

 blue or greyish shale 20 feet. 



None of the fossils listed by Ulrich from this formation 

 are particularly characteristic of the Salona. In 

 Foerste's list (13) Cryptolithus is shown to occur in the 

 Hermitage. 



For the present it seems best to refer the Salona to 

 the basal Trenton. Thus the first 234 feet of Raymond's 

 composite section of the New York Trenton is compar- 

 able to the 640 feet of the Trenton group in Pennsyl- 

 vania. The Salona is placed at the base of the Trenton 

 group and the Rodman at the top of the Stones River, 

 but with the admission that this conclusion may be only 

 temporary and is largely dependent upon conditions as 

 found only in the central Pennsylvanian province. 



