'PLATE XX—Continued. 
RAFINESQUINA, gen. noy. 
Rafinesquina alternata, Conrad. 
(See Plate VIII.) 
Fig. 27. The interior of a brachial valve, with sharply defined anterior and posterior adductor scars, and 
showing faint traces of recurving vascular sinuses. 
Fig. 28. The interior of a pedicle-valve, in which the muscular scars have their normal character. 
Hudson River group. Cincinnati, Ohio. 
Fig. 
Fig. 
Fig. 
STROPHEODONTA, Hall. 
Page 284. 
Stropheodonta profunda, Hall. 
(See Plate XIII, figs. 1-5.) 
An internal cast of the pedicle-valve; showing the broad flabellate diductor 
and enclosing a rather broad pair of adductors. 
An enlargement of the muscular area of the brachial valve. X 11- 
The surface striae. X 2. -vlP 
Niagara limestone. 
rs, meeting in front 
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 32a. Outline profile of the same specimen. 
Trenton limestone. Trenton Falls, N. Y. 
Fig. 33. Outline profile of figure cited. 
