PLATK XXV— Continued. 



Genus C5fRTIA, Dalman. 



Page V). 



Cyrtia cyrtiniformis, Hall and Whitfield. 



Fi(t». 26-28. Three views of a normal example ; ehowing the external charactere. 



Ki(f. 39. A cardinal view ; showing the great height of the area. X 2. 



Fig. 30. The central cai'dinal portion of the conjoined valves ; showing the dental plates of the pedicle- 

 valve, the cardinal process and socket-walls of the brachial valve. X 2. 



Vig. 31. The interior of a portion of the brachial valve ; showing the cardinal process, dental sockets and 

 socket-walls, and the subdivision of the muscular area. X 3. 



Vig. 33. A specimen, showing the crura, jugal pi'ocesses and spiral cones. 

 Hamilton group. Bodfford, Iowa. 



Genus SYRINGOTHYRIS, A. Winchell. 



Page 47. 



Syringothyris Hannibalensis, Swallow. 



¥\g. 33. The exterior of a portion of the brachial valve. 



Fig. 34. A cardinal view of the pedicle-valve ; showing the dellhyrial callosity or canaliferous plate. 

 Fig. 35. The articulating apparatus of the brachial valve. X 2. 

 Choteau limestone. Pike county, Missouri. 



