PLATE XLVI. 



PAGE. 



Fig. 1. Anomalodonta alata, Meek, sp 638 



Interior of a right valve as shown in a gutta-percha impression of a cast of the in- 

 terior, from the Cincinnati group, near Morrow, Ohio. Specimens of this spe- 

 cies often have the wing more extended than is shown in this figure. 



Figs. 2-3. Anomalodonta plicata, n. sp 638 



Two views of a cast of the interior of a right valve. Middle beds of the Cincinnati 

 group, Covington, Kentucky. 



Figs. 4-5. Byssonychia imbricata, n. sp 635 



The left side and a front view of the largest specimen seen. It is a cast of the ex- 

 terior. Middle bsds of the Cincinnati group, Cincinnati, Ohio. 



Figs. 6-9. Byssonychia grandis, n. sp 631 



6 and 7. The left side and an anterior view of an imperfect and slightly distorted cast 

 of the exterior. Upper beds of the Cincinnati group, Oxford, Ohio. 



8. Cast of the interior of a left valve, preserving the outline perfectly. The convex 



region beneath the umboues, however, has been planed away by exposure to the 

 weather; Clarksville, Ohio. 



9. Anterior view of same showing the broad depression around the byssal opening, 



and other features of the species. 



Fig. 10. Byssonychia acutirostris, n. sp. (See also plate 45, Figs. 8 and 9)634 



A small testiferous right valve. The drawing is not exactly true to nature. The 

 back should be a little narrower and the upper fourth of the anterior margin 

 more distinctly concave. About as in Fig. 3 on p ate 47.) 



Figs. 11-14. Ctenodonta perminuta, n. sp .- 680 



Right and left sides of four casts of the interior, x 6, showing slight variations. Cin- 

 cinnati group, Cincinnati, Ohio. 



