EXPLANATION OF PLATE XLYI. 



Page. 



FIG. 1 . Macrodon obsoletus 120 



Right valve. (Keyes collection.) 

 Carboniferous, Upper Coal Measures. 



FIG. 2. Macrodon sangamonensis 121 



Right valve enlarged. ( Hare collection. ) 

 Carboniferous, Upper Coal Measures. 



FIG. 8. Schizodus wheeleri 123 



3a. Side view of cast. (Mus. Iowa State University.) 

 3b. Dorsal aspect of same. 

 3c. Left valve. 



Carboniferous, Upper Coal Measures. 



FIG. 4. Schizodus harii 123 



Left valve. (Hare collection ) 

 Carboniferous, Upper Coal Measures. 



FIG. 5. Astartella concentrica ? 126 



Left valve (Hare collection.) 

 Carboniferous, Upper Coal Measures. 



FIG. 6. Conocardium parrishi 124 



6a. Left valve. (Hare collection.) 

 6b. Dorsal aspect of same. 



Carboniferous, Upper Coal Measures . 



FIG. 7. Astartella vera 125 



Right side . ( Broadhead collection . ) 

 Carboniferous, Coal Measures. 



FIG. 8. Pleurophorus oblongus 125 



Right valve. (Hare collection.) 



Carboniferous, Upper Coal Measures. 

 FIG. 9. Schizodus sp 1. 



Left valve. (Hare collection ) 



Carboniferous, Coal Measures. 

 FIG. 10. Monopteria spl. 



Left valve. (Hare collection ) 



Carboniferous, Upper Coal Measures. 



FIG. 11. Clinopistha radiata . . 124 



lla. Dorsal aspect, 

 lib. Left valve. 



Carboniferous, Coal Measures. 

 FIG. 12. Allorisma costata 128 



Right valve. (Hare collection ) 



Carboniferous, Upper Coal Measures. 



