PLATE I. 



I'AGE. 



Lix(;i;la Covingtonensis fi7 



Fig. 1. View of the exterior of tlie veutial (0 valve, as obtained bj' a gatta-iiercba cast from the 

 matrix. Enlarged to 2 diameters. 



LiNGULELLA CiNCINNATIENSIS 67 



Pig. 2. View of the doisal .side of a specimen, imperfect in the lower part, .showing the beak and area 

 of the vential valve. 

 3. View of a shell, somewhat restored, to .show the general form as seen in other individuals. 



Trematis MILLEPUNCTATA 70 



Fig. 4. Uorsal side of a specimen from Cincinrati, Ohio, showing the general form of tlie shell and 

 some of the external pnnctre around the margin. 

 5. Ventral .side of thr sauip specimen, .shoeing the slit in the posterior margin, 

 fi. Pc otile of the same, showing the relative iiroportion of the vah es and curvature of the beak. 

 7. Iiiterior of a ventral valve, apparently of the same species. All the tigures are enlarged. 



Trematis punctostriata 70 



Fig. 8. View of a ventral valve from the soft shales at Cincinnati, showing the punctate stria^ over 

 a i>art of the surface. 

 9. Ventral valve from the same locality. From the cabinet of XJ. P. James, Esq. 



Leptobolus lepis 69 



Fig. 10. Interior of a dorsal valve, greatly enlarged, showing muscular inpressions, itc. 



11. Interior of a ventral valve, showing mnscular impres.sions and cardinal area. Enlarged. 

 The specimens were from the cabinet of U. B. Dyer, Esq. 



Schizo("raxia filosa 73 



Fig, 12. View of a shell of Strophomena aUernata, t'> which there are five individuals of this species 

 adhering, three of which show r.-niains of the upper valve, and all of them more or less of 

 the lower or attached vah'e. Natural size. 



13. Enlarged view of an upper valve, ime of a sroup of three individuals attached to S. alternata. 



14. Eidargenunt of an upper valve, from which the shell has been removed, showing the ii iis- 



cular iiMi)ressions. The specimen is attached to a valve of Utropluimenn alternata. 



15. Enlaigiiniiit from the ventral valve, seen near the right side of fig. li, sliowing the thicken- 



ing of the margins of the notch. 



Crania l.i^lia 75 



Fig. 16. View of the inner valve of Strfiptorhynchvs plnnvmbona. R.. with four .s])ecimeDS of this 

 species attached. 



Crania scabiosa - 74 



Fig. 17. View'of a specimen of Strojjhonwna alternata, from Cincinnati, Ohio, with a group of these 

 shells adhering. 



Orthis clytie 75 



Fig. 18. View of the inteiior of a ventral valve. 



19. View of the exterior or dorsal side of an entire shell. These figures are from the original 

 specimens of the species. 



Orthis ella 76 



Fig. 20. Dorsal view of one of the original specimens of the species. (See Pal. Ohio, Vol. I., p. 105.) 



Orthis Jamesi 77 



Fig. 21. View of the dorsal side of the largest of the type specimens of this species. 

 22. Profile view of the same. 



Tellinomya levata 82 



Fig. 23. View of the hinge of an imperfect specimen of this species. Enlarged. 



Tellinomya pectunculoides 81 



Fig. 24. View of the interior of a specimen from the cabinet of C. B. Dyer, Esq. Enlarged. 



Lyrodesma Cixcinnatiensis 82 



Fig. 25. Enlarged view of the interior of a right valve, showing the character of the hinge. Cabinet 

 of C. B. Dver, Es(|. 



