PENNSYLVANIAN FOSSILS 



117 



Fig. 332 



Fig. 333 



Worthenia is a low-spired, highly ornamented snail with both axial 

 and spiral ridges whose intersection forms strong nodes. W. beedei (fig. 

 332) is the common species. 



Schizostoma ( Euomphalus in older publications) is coiled in one plane 

 and the spire is sunken below the level of the body whorl. J>. catilloides 

 (fig. 333) is common in some beds. 



Pharkidonotus ( Bellerophon in older publi- 

 cations) is one of 3 genera of bellerophontids in 

 which the spire is entirely hidden inside the body 

 whorl (fig. 334)). It is distinguished from 



Euphemites and Patellostium by its strong axial ridges and the lack 



of spiral ridges. Several species are common. 



Euphemites ( Euphemus in older publications) is similar to 



Pharkidonotus in form 

 but it has spiral orna- 

 mentation that is 

 stronger than the axial. 



or more spiral ridges. E. nodocarinatu s (fig. 

 335) has a single spiral ridge on the middle of the 

 whorl and the ridge bears a series of nodes. 



Patellostium is like the last 2 genera in form 



but it seems to combine 



the ornamentation of 



both. The spiral ridges 

 are of two sizes, two large ones separated by three to five smaller 

 ones, and it also has strong axial folds. P. montfortianum (fig. 336) 

 is common; most specimens are crushed but recognizable by their 

 ornamentation. 



Loxonema and the remainder of our Pennsylvanian genera all 

 have a spire that projects above the body whorl. In fact, in Loxonem a Fig. 336 



and several of the following genera, the spire is high and the length 

 much greater than the width. The only common species is L. scitulum (fig. 337) of the 

 Conemaugh. It probably belongs in some other genus but for the present can still be called 

 Loxonema. 



Fig. 335 



Fig. 334 



E. carbonarius has 16 



Aclisina (fig. 338) resembles 

 Loxonem a. One group of species has 

 only spiral ridges, the other has both 

 spiral and axial ones. The species 

 with spiral ridges only can be distin- 

 guished from Qrthonema by the great- 

 er number of spiral ridges (only three 

 in Qrthonema ). Those with axial and 

 spiral ornamentation can be distin- 

 guished from Loxonema by the 

 presence of the latter. Several species 

 of Aclisina are common. 



Fig. 338 



Fig. 339 



The species of Qrthonema can be distinguished from Loxonema and Aclisin a by the 

 character of the ornamentation. O. subtaeniatum (fig. 339) has only 3 spiral ridges on the 

 whorl; O. bilineatum resembles some species of Aclisin a but it has fine axial ridges and only 

 2 spiral ridges near the top of the whorl. Both species are common in some beds. 



