1 88 NEW YORK STATE MUSEUM 



The Trilobite bed for which the Lower Oriskany here is specially 

 noted is a dense, dark blue limestone containing many trilobite frag- 

 ments, specially of Dalmanites dentatus and H o m a 1 o - 

 n o t u s V a n u X e m i . The former species is specially abun- 

 dant, whence the name " dentatus fauna " for the Lower Oriskany. 

 It likewise contains a great abundance of Rensselaeria sub- 

 globosa, Chonostrophia jervisensis, Actinop- 

 teria textilis and Loxonema j e r s e y e n s e. It is 

 bounded above and below by an inch of silicious limestone. This 

 bed maintains a uniform thickness of from 4 to 6 inches. 



Upper Oriskany (Spirifer murchisoni zone) 



The upper Oriskany is characterized by dark blue silicious lime- 

 stone and shale, and has an approximate thickness of 150 feet. 

 Chert bands occur more or less frequently throughout the entire 

 formation, but specially in the upper portion. At times these show 

 no traces of any fossils even when weathered ; at other times they 

 are one mass of fossils. Unlike the chert bands of the upper Coey- 

 mans and Lower New Scotland, these fossiliferous bands apparently 

 contain no bryozoa. 



This formation is specially characterized by Spirifer mur- 

 chisoni, Meristella lata, Leptocoelia flabel- 

 lites, Coelospira dichotoma, Actinopteria 

 textilis arenaria, Diaphorostoma ventricosum 

 and Tentaculites elongatus. The lower portion con- 

 tains an abundance of Orbiculoidea jervisensis. This 

 large brachiopod is very noticeable, even at quite a distance from the 

 exposure, as it occurs frequently at right angles to the bedding. 

 The most characteristic fossil is Spirifer murchisoni, and 

 hence the name " murchisoni zone." 



are present. Omitting from the above all species marked questionable, there 

 remain 15 characteristic of the Oriskany or later (Onondaga) and 5 of the 

 Helderbergian. [Safford, J. M. & Schuchert, Charles. The Camden (Tenn.) 

 Lower Oriskany. Am. Jour. Sci. ser. 4? 7:429-32] 



This Camden Oriskany is developed at least as far north as western Mary- 

 land where, according to Schuchert, the lower portion of the Oriskany 

 "recalls the Oriskany of Camden, Tennessee, and points to an older stage 

 than the Oriskany as usually known." [Schuchert. On the Lower Devonic 

 and Ontaric Formations of Maryland. U. S. Nat Mus. Proc. 26 :42o] 



