OllTHIS (DaLMAN^LLA.) SUPER8TE8, Hall. 



Page 341. 

 Figs. 15, 16. Dorsal and profile views of the exterior. 

 Fig. 17. The interior of the brachial valve, showing cardinal process, adductor 



scars and vascular sinuses . 

 Fig. 18. An internal cast of the pedicle:valve; showing traces of the vascular 

 sinuses . 

 Chemung group . Hoivard, N. Y. 



Orthis Holstoni (Safford), Hall. 

 Page 339. 

 Figs. 19, 20, 21. Ventral, profile and cardinal views of the type specimen. 

 Trenton horizon . Near Knoxville, Tennessee. 



Obthis (Schizophoeia) senecta, Hall. 

 Page 342. 

 Fig. 22. The exterior of a pedicle- valve; showing the depression over the 



pallial region . 

 Fig. 23. An internal cast of a pedicle- valve; showing the diductor and 

 adductor scars . 

 Clinton group. Reynctle's Basin, N. Y. 



Orthis (Rhipidomella) Oweni, Hall. 



Page 341. 

 Fig. 24. The interior of a brachial valve. 

 Fig. 25. The exterior of a brachial valve. 

 Fig. 26. The interior of a pedicle- valve. 

 Waverly group. Button-mould Knobs, Kentucky. 



Stuophomena Conradi, Hall. 



Page 343. 

 Fig. 27. Doi'sal view, showing the reversed convexity of the valves, and the 

 fasciculate striae . 



Fig. 28. Outline profile of the same specimen. 

 Trenton limestone . Jacksonburg, N. Y. 



Fig. 29. Profile of a brachial valve . 



Fig. 30. Outline profile of both valves of the same specimen. 

 Trenton limestone. Trenton Falls, N. Y. 



SXROPHOMENA WiNCHELLI, Hall. 



Page 344. 

 Fig. 31. The exterior of a brachial valve, showing its great convexity and the 

 fine filiform radial striae of "the surface . 

 Trenton limestone. Clifton, Wisconsin. 

 Fig. 32. The interior of a brachial valve. 

 Trenton limestone. Janesville, Wisconsin. 



Fig. 33. The interior of a pedicle- valve, showing the character of the muscu- 

 lar area and the submarginal thickening of the shell. 

 Trenton limestone. Clifton, Wisconsin. 



381 



