118 



OHIO FOSSILS 



Sphaerodoma (fig. 340) has a large body whorl, as compared with the 

 last 3 genera. The spire is sharply pointed as compared with the next 2 

 genera. Several species of Sphaerodoma are common. 



The most conspicuous character of Phanerotrem a is the crinkled ap- 

 pearance of the axial ornamentation. The shell is wide and the 

 aperture large. P. grayvillensis (fig. 341) is common in some 

 beds. 



Bulimorpha minuta (fig. 342) of the Conemaugh is a very 

 small shell with fine, straight axial ornamentation. The body 

 whorl is large, as in Phanerotrema grayvillensi s but size alone 

 is sufficient to separate the two. 



Several Pennsylvanian species are placed in the genus 

 Pleurotomaria (see fig. 264) which may not be a Paleozoic genus 

 at all. For lack of a better generic assignment, we are leaving 

 these species in Pleurotomaria . They are small forms with rather low spire and 

 strong spiral ridges. One species is common and several others are rare. 



Fig. 340 



Fig. 341 



Fig. 342 



Fig. 343 



In Soleniscus (fig. 343) the aperture and spire are almost equal in length. 

 The genus is distinguished from Pleurotomaria by the absence of spiral ridges. 

 Several species are common in some beds. 



CEPHALOPODA . This class of the Mollusca is represented sparingly in 

 the Pennsylvanian of Ohio. Only a few species can be called common. The 



existing fossil remains represent only a small fraction of the forms that lived in our Pennsyl- 

 vanian seas for they belong to a large number of species, almost all represented by rare 

 individuals. 



Unklesbay (1954) has summarized the distribution of American Pennsylvanian cephalopods. 

 His paper contains several lists for Ohio formations. Miller and Sturgeon revised the ammo- 

 noids and nautiloids in several papers which are noted under these groups. 



Our nautiloid cephalopods include both straight and coiled forms. Two straight forms 

 are recorded as common: " Qrthoceras " rushense (fig. 344) of the Conemaugh, almost 

 certainly belongs in some other genus, not as yet determined; and Pseudorthoceras knoxense 



_______ (fig. 345) of the 



t TY"\ ' I M TTMTTrrm Pottsville. 





Fig. 344 



Fragments of coiled cephalopods (fig. 

 346) are not uncommon in our Pennsylvanian 

 but their identification requires more detailed 

 Flg - 345 description than could be given here. The 



nautiloids have been revised by Sturgeon (1946) and Sturgeon and 

 Miller (1948). The ammonoid cephalopods of the Ohio Pennsylvanian 

 are likewise rare and varied. The species have been revised by 

 Miller and Sturgeon (1946). 



Fig. 346 



