PLATE LXVII— Continued. 



Pentamerus oblongus, var. Maquoketa, vai-. iiov. 



Figs. 11, 12. Dorsal and profile \-iews of an internal ca-st of a characteristic example ; showing the ovoid 



and regularly convex valves. 

 Fig. 13. A cardinal view of another individual ; showing the position and e.xtent of the internal plates. 

 Niagara dolomites. Near Diibagite, Iowa. 



Pentamerus oblongus, Sowerliy. 



Fig. 20. The interior of the umbonal portion of a silicified shell ; showing the spondylium and median 

 septum. 



Niagara dolomites. Hillsboiv, Ohio. 



