PLATE IXa. 



(Figures 1-27 by R. P. Whitfield.) 



Legend. D. Deltidium, pedicle-valve. p. Pedicle muscle. 



C. Deltidium, brachial valve. a'. Anterior adductors. 



t. Teeth. a. Posterior adductors, 

 b. Dental sockets. r. Diductors. 



c. Crural plates. v. Vascular sinuses. 



X. Crural bases. 



Genus EAFINESQUINA, gen. nov. 



Page 281. 



Kafinesquina deltoidea, Conrad. 



Fig. 1. The exterior of a pedicle-valve J showing its regular convexity and deep anterior deflection, the 



radiating stria; of snbequal size, and the concentric corrugations. 

 Fig. 2. Profile of the same specimen ; sliowing the regular convexity from umbo to anteiior margin. 



Trenton limestone. J acksonhurg, N. Y. 

 Fig. 4. An impression of the exterior surface nf the brachial valve ; showing its subtriangular outline as 

 usually developed in this species, and the flattened, scarcely concave circumbonal area. 

 Trenton limestone. MiddlevUle, N. T. 

 This figure is from the original specimen used by Mr. Conbad, and is the subject of the drawing 

 by him reproduced in Paleontology of New York, Vol. I, plate xxxiA, fig. 3/. That figui-e, 

 however, gives the valve a convexity which it does not possess. For further illustration of the 

 species, the other figures on the plate cited may be consulted. 



Genus STROPHOMENA, Raeinesqub (de Blainville). 



Page 245. 



Steophomena Conradi, sp. nov. 



Fig. 3. View from the brachial valve ; showing the reversed convexity of the valves, and the fasciculate 

 sui-face striae without concentric i-ugae. 



Trenton limestone. Jaclcsonburg, N. Y. 



Stkophomena nutans, James (Meek). 



Fig. 5. The exterior of a brachial valve. 



Fig. 6. The interior of a iiedicle-valve ; showing the characlei' of the muscular impressions and vascular 



markings. 

 Fig. 7. The central cardinal poi-tion of the brachial valve ; showing the bilobed cardinal process, the 

 curved crui'al plates, and the muscular impressions. X 3. 

 Hudson River group. Oxford, Ohio. 

 For other illustmtions, see Palteontology of Ohio, Vol. I, i3late vi, fig. 1. 



Strophomena planumbona, Hall {^S. rugosci, Eatiuesque). 



Fig. 8. An enlargement of the cardinal process and crural plates. X 2. 



Fig. 9. The corresponding portion of the opposite valve ; showing the irregularly crenulated character of 

 the surface of the teeth. X 2. 



Hudson River group. Oxford, Ohio. 



Strophomena filitexta, Hall. 



Fig. 10. The interior of a brachial valve ; showing the cardinal process, muscular area, and the elevated 

 median ridges of the vascular system (?). 



Hudson River group. Waynesville, Ohio. 



Fig. 11. The interior of a pedicle-valve ; showing the limitation of the muscular area by an elevated bor- 

 der, which is continuous from the dental plates. 



Fig. 12. Exterior of a brachial valve ; showing the tendency to plication of the surface. 



Fig. 13. A cardinal view of a specimen I'etaining both valves, and showing the i-esupination of the shell. 



