PLATE XX— Continued. 



RAFINESQUINA, gen. nov. 



Page 281. 



Rafinesquina alternata, Conrad. 



(See Plate VIII.) 



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



showing faint traces of recurvingf vascular sinuses. 

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

 Hudson River group. Cincinnati, Ohiti. 



STROPHEODONTA, Hall. 



Page 284. 



STKOPnEODONTA PROFUNDA, Hall. 



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



Kg. 29. An internal cast of the pedicle- valve ; showing the broad flabellate diductor scars, meeting in front 



and enclosing a i-ather bi'oad pair of adductors. 

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

 Fig. 31. The surface striae. X 2. 



Niagara limestone. Near Milwaukee, Wisconsin. 



STROPHOMENA, Rafinesque (de Blainville). 



Page 245. 



Strophomena Conradi, sp. nov. 



(See Plate XI A, fig. 3.) 

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

 Fig 32a. Outline profile of the same specimen. 



Ti-enton limestone. Trento7i Falls, N. Y. 

 Fig. 33. Outline profile of figure cited. 



