Plate Page 



1. Genus Triletes 105 



2. Genus Triletes 106 



3. Genus Triletes 109 



4. Genus Triletes 110 



5. Genus Triletes 113 



6. Genus Triletes 114 



7. Genus Triletes 117 



8. Genus Triletes 118 



9. Genus Triletes 121 



10. Genus Triletes and Triletes? 122 



11. Genus Triletes? and Cystosporites 125 



12. Genus Cystosporites 126 



13. Genus Spencerisporites and Calamospora 129 



14. Genus Monoletes and Parasporites 130 



15. Genus Punctatisporites y Reticulatisporites, Renisporites, Densosporites, and seed mem- 



branes 133 



16. Seed membranes, miscellaneous plant micro fossils, and membranes of animal (?) 



origin 134 



TABLES 



Table Page 



1. Comparative data on megaspores of the Triletes hirsutus and T. globosus types ... 41 



2. Geographic locations in Illinois 69 



3. Geographic locations in states other than Illinois 72 



