PLATE 12. 
Puge 
Figs. 1-5. Strophodonta demissa. 81 
1, 2. Dorsal and ventral views of a small individual. 
3-5. Dorsal and ventral views and profile of a larger specimen. This individual is the largest 
one observed in the Corniferous limestone. 
Figs. 6-8. Strophodonta ineqtjistriata. 93 
6, 7. Dorsal and ventral views"of a specimen of ordinary size. 
8. Profile of a larger and very gibbous specimen. 
Figs. 9-11. Strophodonta patersoni. ?. 89 
9. A ventral valve of a specimen of ordinary size, but more convex than usual. 
10. A profile of the preceding specimen. 
11. An enlargement of the striae from the same shell. 
Fig 12. Strophodonta inequiradiata. 87 
12. The cast of a ventral valve which may belong to this species. 
Figs. 13-15. Strophodonta perplana. ... 92 
13. A young individual corresponding in size and character to the original of S. crenistria 
as described in the Geol. Report of the 4th District. 
14. A dorsal view of a large individual of the same species. 
15 A cast of the ventral valve of the same species in chert, from Indiana. 
Figs. 16-18. Strophomena rhomboidalis. 76 
16. An individual with numerous regular undulations. This is of the type of S. undulata, of 
Yanuxem’s Geol. Report of 3d District. 
17. A specimen with few strong undulations. 
18. A cast of the ventral valve showing few undulations. 
