PLATE LXVI— Ck)ntinued. 



CoNCHiDiuM Greenii, sp. nov. 



Figs. 20-22. Profile, cardinal and ventral views of a specimen somewhat restored about the margins ; 

 showing the short, ventricose valves and fine, duplicate plication. 

 Niagara dolomites Near Milwaukee, Wisconsin. 



CoNCHIDIUM, tjJJ. 



Fig. 23. An internal cast of the pedicle-valve of a probably undescribed species ; showing the character 

 of the plication and the length of the median septum. 

 Niagara dolomities. Hawthorne, Illinois. 



CONCHIDIUM CRASSIPLICA, Sp. IIOV. 



Figs. 24, 25. Dorsal ami profile views; showing the ovate form of the shell, the subequally convex valves, 

 short and depressed beak of the pedicle valve and the coarse, duplicate plication of the 

 surface. 



Niagara group. Prohahl i) from the vicinity of Louisville, Kejitucky. 



