PLATE XIII -Continued. 



PeNTAMEEUS (PenTAMERELLA?) VENTRIC0SU8, HaLL 



:Page 382. 



Figs. 18-21. Dorsal view, profile, cardinal and front views of a medium-sized individual of the 

 species, showing slight indications of plications on the mesial fold and sinus. 



Pentamerus multicostatus. Hall. 



;Page 381. 



Figs. 22-24. Dorsal view, profile, and cardinal views of an internal cast of this species, preserving 

 the impressions of the costse on the anterior margin. 



