PLATE LXVI—Continued. 
CoNCHiDiuM Geeenii, sp. nov. 
Figs. 20-22. Profile, cardinal and ventral views of a sj^ecimen somewhat restored about the margins; 
showing the short, ventricose valves and fine, dtiplicate plication. 
Niagai'a dolomites. Near Mlhoaukee, Wisconsin. 
CONCHIDIUM, sp. 
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. Haiotlim'ne, Illinois. 
CONCHIDIUM CRASSIPLICA, Sp. IIOV. 
Figs. 24, 25. Dorsal and 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. Probably from the vicinity of Louisville, Kentucky. 
