FAUNA OF THE HELDERBERGIAN 



Table of the Helderbergian Fauna 



289 



Lichas (Conolichas) bigsbyi Hall. 4820 



" " pustulosus Hall. 486i, 4950. 



" (Arges) consanguineus Clarke 



f Acidaspis tuberculata (Conrad). 4949 



{Dicranurus) liamata (Conrad) 



Lepidocoleus polypeialus Clarke 





> 



C 



6 





5 

 i— i 





cs 

 s 

 s 

 s 

 s 

 s 



397 





X 



17 







56 



64 



74 



40 



c£ 



el 



o3 



MX) 



Ch 



22 



ORISKANIAN SUBDIVISIONS 



Slratigraphic names applied to the Oriskanian. — The Oriskany formation 

 was noticed by Eaton, who named it " Shell Grit." During the progress 

 of the New York Geological Survey it was studied in detail, and was 

 known as the " White sandstone," or the "Grey Brachiopodous sand- 

 stone." In 1839 Vanuxem gave it its present name from Oriskany falls. 

 Clarke has called its fauna the " Hipparionyx Fauna," which practically 

 comprises all that was known as the Oriskany prior to 1892. In Penn- 

 sylvania, the Oriskany is called division " Number 7 ; " in Maryland and 

 Virginia, the " Monterey formation ; " in northern Alabama, the " Frog 

 Mountain sandstone ; " in western Tennessee, " Camden chert; " and in 

 southwestern Illinois," Clear Creek limestone." In northeastern Canada 

 the formation is present in divisions 7 and 8 of the " Gaspe limestone," 

 and it may also continue into the lower portion of the " Gaspe sand- 

 stone." Possibly the formation has received other names, but no par- 

 ticular pains has been taken to collect them, since the first geographical 

 name is the Oriskany of Vanuxem. 



General character and distribution of the Oriskanian. — In a general way, 

 it may be said that the Oriskany formation extends with many interrup- 

 tions along the eastern and northern flanks of the Helderberg mountains 

 of New York. Along the northern side, the Upper Oriskany only is 

 known to be present, exceedingly variable in thickness, but never more 

 than 30 feet, diminishing in volume and resting westwardly upon the 

 successive lower horizons of the Helderbergian and finally on the Siluric. 

 In the region of Cayuga lake it is sparingly present, and is practically 

 absent west of Ontario county, the Corniferous or Onondaga then rest- 



XLII— Bull.^Geol. Soc. Am., Vol. 11, 1899 



