100 



OHIO FOSSILS 



Fig. 247 



Dictyoclostus , another 

 productid, also has one 

 convex and one nearly flat 

 valve. It is separated 

 externally from Buxtonla 

 by its continuous radiating 

 ridges which are interrupt- 

 ed in Buxtonia. Several 

 species of Dictyoclostus 

 are common in the Cuyahoga 

 and Logan. Very large 

 forms from the Logan are 

 likely to be D. bovis (fig. 

 247). 



Rhipidomella (fig. 248) has a thin shell with one slightly convex and one almost flat valve. 

 The radiating ornamentation is distinct but fine and thread-like. Rhipidomella resembles 

 Schuchertella and Schellwienella but has a shorter hinge line. Two species 

 of Rhipidomella are common in some beds of the Cuyahoga and Logan. 



Syringothyris is distinguished from Spirifer , which it resembles in 

 general outline, by its very high cardinal area. Species of this genus are 

 among the largest of our Mississippian brachiopods. Several species 



Fig. 248 



Fig. 249 



have been recorded from Ohio. S. typus (fig. 249) is common in the Logan. 



Spirifer has a strong sinus and fold, as in Syringothyris , but a lower cardinal area which 

 is characteristic. Two species are found in our Mississippian rocks; the commoner one is 



S. centronatus (fig. 250) of 

 the Logan. S. striatiformis 

 (fig. 251) is common, in the 

 Cuyahoga. 



Fig. 250 



Fig. 251 



