PLATE LXVII— Continued. 



Pentamerus OBLONOU8, vjir. Maquokbta, var. iiov. 



Figs. 11, 13. Dorsal and profile views of an internal cast of a chm-acteristic example ; showing the ovoid 



anil regularly convex valves. 

 Fi^. 13. A cardinal view of another individaal ; showing the position and extent of the internal plates. 

 Niagara dolomites. Near Jhil/uque, Iowa. 



Pentamerus oblongus, Soweihy. 



Fig. 30. The interior of the umbonal portion of a silicified shell ; showing the spondylium and median 

 septum. 



Niagara dolomites. HUlsboro, Ohio. 



i 



