LOWER OKISKANY FAUNA OF TENNESSEE 



321 



Anoplia nucleata, Anoplotheca fab ell lies, Eatonia pecidiaris, Spirifer worihen- 

 anus, S. hemicyclas, Megalanleris condoni, Amphigenia curia, and Strophoslylus 

 cancellalus. 



The " Clear Creek limestone " of Illinois is intimately connected with 

 the Helderbergian below, and is not less than 200 feet thick, being fol- 

 lowed by a " quartzose sandstone " from 40 to 60 feet in depth. The latter 

 is probably equivalent to the Upper, or typical, Oriskany of New York, 

 and does not appear to be present in western Tennessee. From Pro- 

 fessor Safford's description of the Camden chert, it is evident that the 

 Lower Oriskany thins rapidly southward. In Tennessee it is about 60 

 feet in thickness, while it is not less than 200 feet thick in Illinois, 

 exclusive of the Upper Oriskany which is entirely absent in the former 

 state. 



The Camden chert fauna contains 32 species, and 6 of these are re- 

 stricted to southern Illinois and western Tennessee. Of the entire fauna, 

 24 species are found either in the Helderbergian or in the Lower Oriskany 

 of other regions, and 20 occur in the Upper Oriskany, or Onondaga. 

 After removing the 13 species common to both the Lower and Upper 

 Oriskany and the 2 restricted forms, 17 remain. Of these 10 occur either 

 in Helderbergian or Lower Oriskany rocks of other regions, while 6 are 

 found in higher beds. This evidence therefore indicates clearly a Lower 

 Oriskany age for the Camden chert of Tennessee and the " Clear Creek 

 limestone " of Illinois, which indication is the more marked because of 

 the absence of such characteristic Upper Oriskany species as Hipparionyx 

 proximuSj Chonosirophia complanata, Spirifer arenosus, Rensselxria cvoides, 

 Meristella lata, Camarotoschia pleiopleura, C. barrandei, or C. speciosa. 



The following is the Lower Oriskany fauna of the Camden chert or 

 Camden, Benton county, Tennessee : 



a 



03 

 M . 



02 O 



A ® 



g © 



o 



<v 



& . 



oq 0> 



Q* 02 



Zaphrentis roemeri Hall ? 26938 



Pholidops terminalis Hall. 26939. ... .- 



Hipparionyx proximus Vanuxem? A very small specimen of this 



species. 26940 



Chonetes mucronatus Hall ? 26941 . . . 



" mdonica Billings. 26942, 26943 



Clionostrophia reversa (Whitfield). 26944 



H* 

 x 



X 

 X 

 X 



O 



* H = Helderbergian ; O = Ouondaga. 

 XLVI— Bull. Gkol. Soc. Am., Vol. 11, 1899 



