PLATE XX— Continued. 



RAFINESQUINA, gen. nov. 



Page 231. 



Rafinesquina altbrnata, Conrad. 



(See Plate VIII.) 



Fig. 27. The interior of a brachial valve, with sharply defined anterior and posterior adductor scare, and 



showing- faint traces of recurving- vascular sinuses. 

 Fig. 28. The interior of a pedicle-valve, in which the muscular scars have theij- normal character. 

 Hudson River group. Cincinnati, Ohio. 



STROPHEODONTA, Hall. 



Page 284. 



Stropheodonta profunda, Hall. 



(See Plate XIII, figs. 1-5.) 



Fig. 29. An internal cast of the pedicle- valve ; sho-wing the broad flabellate diductor scars, meeting in front 



and enclosing a rather broad pair of adductors. 

 Fig. 30. An enlai-gement of the muscular area of the brachial valve. X 1^. 

 Fig. 31. The surface strise. X 2. 



Niagara limestone. Near Milwaukee, Wisc(msin. 



STROPHOMENA, Rafinesque (de Blainville). 



Page 245. 



Strophomena Conradi, sp. nov. 



(See Plate XIa, fig. 3.) 

 Fig. 32. The profile of a specimen showing only the upper or brachial valve. 

 Fig 82a. Outline profile of the same specimen. 



Trenton limestone. Trenton Falls, N. Y. 

 Fig-. 33. Outline profile of figure cited. 



