536 NEW YORK STATE MUSEUM 



Scliizocrinus nodosus, Hall 



PacJijtdictya acuta, Hall sp. > 



cf. Esciharopora angularis, Ulrich 



Prasopora sp. 



Dalmanella testudinaria, Dalma/n sp. 



Plectorthis plicatella, Hall ' 



Platyisitrophia biforata, Schlothemi sp. 



Plectambonites sericea, Sowerly sp. 



Rafiniesquina alternata, Emmons (sp. 



Khyncliotrema increbescens, Hall sp. (= inaequivalvis, Castel- 

 noAi sp.) 



Proetus parviusculus, Hall 



Of these species Schizocrinus nodosus indicates the 

 Trenton age in general, while Pachydictya acuta is re- 

 ported by Hall (7 : 75) as " of frequent occurrence in both the 

 lower and central portions of the Trenton limestone ", a state- 

 ment with which Winehell and Ulrich concur in reporting the 

 fossil from the Clitambonites, Fusispira and Nematopora beds of 

 Minnesota (49: 111). Eschar op or a is, according to the 

 same authors, restricted to the Stones river, Black river, lower 

 * and central Trenton beds. Khynchotrema increbes- 

 c e n s, in the restricted meaning (i. e. with the exclusion of the 

 distinct Lorraine form, R. c a p a x, originally included by Hall in 

 this species) is a Trenton form. In the west it occursi in the upper 

 Black river group, lower and middle Trenton (49: cxv) and in 

 Canada it is found in Black river and lower Trenton. It is, 

 hence^ indicative of the lower or middle Trenton age of the Troy 

 beds. Proetus p a r v i u s c u 1 u s was originally described 

 by Hall (14: 223) as occurring "in shales of the Hudson river 

 group, Cincinnati, Ohio ". The correlation of these shales has, 

 however, changed since that time; for Winehell and Ulrich 

 cite the form from the Trenton of the Cincinnati region. Dr 

 Clarke (49: 754) reports it from the base of the Galena shales 

 at St Paul (Clitambonites bed, Winehell and Ulrich, which is 

 lower Trenton). In Canadia it has also been found in the Trenton. 



