PAGE. 



Figs. 32 to 35. ANASTROPHIA (?) HEMIPLICATA, var. ROTUNDA, n. var 383 



32 and 33. Views of the ventral and dorsal valves respectively. 



34 and 35. Profile and anterior views of the same. specimen. Galena shales, near Cannon 

 Falls, Minn. Minnesota Geological Survey collection. 



Figs. 36 to 40. STROPHOMENA INCIJRVATA Sheppard, sp 385 



36. Dorsal view of a very convex specimen in which the striae are nearly of equal size. 



37. Profile view of the same specimen. The dotted line indicates the curvature of 



the ventral valve. Trenton shales, Lanesboro, Minn. 



38. Interior of a well preserved ventral valve, showing the muscular scars, genital 



markings and vascular sinuses. Trenton shales, Minneapolis, Minn. Collec- 

 tion of C. Schuchert. 



39. The interior of a dorsal valve, showing the cardinal processes, dental sockets, 



genital markings and vascular sinuses. Trenton shales, St. Paul, Minn. 



40. Profile outline of a less gibbous specimen than fig. 37. Lower Blue beds, Dodge- 



ville, Wisconsin. Minnesota Geological Survey collection. 



Fig. 41. STROPHOMENA TRENTONENSIS, n. sp 389 



The interior of a ventral valve. Trenton shales, Minneapolis, Minn. Minnesota 

 Geological Survey collection. 



