Trematospira Tbnnesseensis, Hall. 

 Page 360. 

 Figs. 17, 18, 19. Dorsal, profile and ventral views, showing the convexity and 

 coarse plication of the valves. 

 Lower Helderberg group. Ferry county, Tennessee. 



Merista Tbnnesseensis, Hall. 



Page 361. 



Figs. 20, 21 . Two views of the exterior of a somewhat elongate example. 



Fig . 22 . Dorsal view of a broader example. 



Fig. 23. The exterior of the pedicle- valve, showing the cavity left by the 

 removal of the " shoe-lifter. " 



Fig. 24. The interior of a pedicle-valve. 

 Kg. 25. The interior of a brachial valve. 

 Lower Helderberg group. Perry county, Tennessee. 



Meristella Walcotti, Hall. 



Page 360. 

 Fig. 26. The hinge-plate, x 3. 



Fig. 27. An internal longitudinal view; showing the position and form of the 

 jugum and one of the spiral cones. 



Fig. 28. The spirals and jugum naturally preserved by incrustation and 

 viewed from the posterior margin. 



Fig. 29. A similar preparation to which a portion of the internal cast of the 

 valves adheres. The specimen is viewed from the dorsal side, and shows 

 the form of the spiral cones and the length of the median septum. 



Figs. 30, 31. Dorsal and profile views of the exterior. 

 Oriskany sandstone. Cayuga, Ontario. 



389 



