320 REPORT ON THE STATE CABINET. 



This species differs from E. coralifera of New York in its genei^al broad 

 trianeular form, absence of mesial elevation on the dorsal valve, and 

 undefined sinus on the lower part of the ventral valve ; in the finer 

 reticulations, as well as the flattening of the interspaces. From E. 

 reticulata it differs in the finer and more elongate pits and entire absence 

 of mesial fold ; although that species sometimes has a scarcely-defined 

 fold, yet the reticulation is always much coarser. 



Geological Formation and Locality. — In rocks of the age of the Niagara 

 or Lower Helderberg, Tennessee. 



