360 ^ Report of the State Geologist. 



inside it bears a short but well defined spondylium supported by 

 a median septum, and strong recurved teeth. This structure 

 is unlike that of any other genus. 

 St. Louis group. La Rue^ Kentucky. 



Rhynchospira scansa. 



Plate 9, fig. 2. 



Rhynchospiras scansa, Hall. Palaeontology of N. Y., vol. VIII, pt. 2, expl, 

 pi. 1, fig. 45. 1894. 



Pedicle-valve large, with prominent,, somewhat arched beak, 

 cardinal slopes extending about one-half the length of the shell, 

 anterior margin semioval. Surface with a sharply defined median 

 furrow bearing a single small plication, the lateral slopes having 

 eight or ten broad and rounded plications. Shell known only 

 fron an internal cast of the pedicle-valve. 



Waverly group. McKean county^ Pennsylvania. 



Trematospira Tennesseensis. 



Plate 8, figs. 17-19. 



Trematospira Tennesseensis, Hall. Palaeontology of N. Y., vol. VIII, pt. 2, pi. 

 Ixxxiii, figs. 21-23. 1894. 



Shell small, subelliptical or subcircular in outline. Valves 

 coarsely plicate, the pedicle- valve bearing six, with a small median 

 plication at the bottom if the sinus, the brachial valve having the 

 median fold divided by a low furrow, and with three plications 

 on each lateral slope. Yalves subequally convex. Apex of the 

 pedicle- valve slightly elevated, truncate; deltidial plates coalesced. 

 Surface with distant concentric growth-lines. 



Lower Helderberg group. Perry county, Tennessee. 



Meristella Walcotti. 



Plate 8, figs. 26-31. 



Meristella Walcotti, Hall. Palaeontology of N. Y., vol. VIII, pt. 2, p. 365, pi. 

 xliii, figs. 16, 17; pi. xliv, figs. 6-11, 23, 32. 1894. 



Shell elongate-ovate, valves convex, regular. Pedicle-valve 

 with umbo moderately full and beak incurved ; foramen generally 

 concealed at maturity. Cardinal slopes concave and well delimited 

 by divergent cardinal ridges. Dorsum more or less distinctly ridged 



