PLATE XIII. 



Barrandella Areti, Hall. 



Page 369. 



Figs. 1, 2, 3. Dorsal, profile and ventral views; showing the strongly plicated 

 fold and sinus on brachial and pedicle-valves respectively, and the sharp 

 plication of the lateral slopes, x 2. 

 Clinton group . Rochester, N. Y. 



SlEBERELLA ROEMERI, Hall, 



Page 370. 



Fig. 4. Dorsal view of an individual of rather large size; showing the charac- 

 teristic plication of the sinus and lateral slopes and their obsolescence in 

 the umbonal region . 

 Upper Silurian. Perry county , Tennessee . 



Capellinia mira, Hall 

 Page 368. 



Fig. 5. Cardinal view of a pedicle-valve; showing the suberect beak and wide 

 delthyrium . 



Fig. 6. Ventral view of the same specimen . 



Figs. 7, 8. Cardinal and ventral views of a normal example; showing the pre- 

 dominant convexity of the brachial valve, the smooth surface and the 

 position and extent of the internal plates. 



Fig. 9. A brachial valve, showing the length of the septal plates . 



Figs. 10, 11. Ventral and profile views of a specimen in which the umbo of 

 the pedicle- valve is abruptly depressed. 



Fig. 12. Cardinal view of another example . 



Fig. 13. Profile of a normal individual. 

 Niagara dolomites . Near Milwaukee, Wisconsin. 



Rensselaeria Catuga, Hall. 

 Page 370. 

 Figs. 14, 15. Dorsal and ventral views of a specimen which retains most of the 

 shell and shows the fine plication of the valves. 

 Oriskany sandstone . Cayuga, Ontario . 



400 



