10 



ILLUSTRATIONS. 



PLATE xliv. Lamellibranchs. 



xlv. Lamellibranchs. 



xlvi . Lamellibranchs . 



xlvii. Lamellibranchs. 



xlviii. Gasteropods. 



xlix. Gasteropods. 



1. Gasteropods. 



li. Gasteropods. 



lii. Gasteropods. 



liii. Cephalopods. 



liv. Cephalopods. 



FIGURES IN PART I. 



FIGURE 1. Section at Railroad Bridge north of Fredericktown, Madison county, show- 

 ing contact of Cambrian and Archasan. 



2. Ideal section of the Deposition of the Ozark Rocks 



3. Relation of Saint Louis and " Warsaw " beds at Keokuk, Iowa. 



4. False bedding of Oolite at Ste. Genevieve. 



5. Relation of the Aux Vases Sandstone. 



6. Eocks at Chester ( Illinois ) showing Coal Measure sandstone resting on Kas- 



kaskia limestone and shales. 



7. Line of juncture at figure 6. 



8. Lower Coal Measures resting on Brecciated Saint Louis limestone at Keokuk , 



Iowa. 



9. Plan of Actinocrinus. 



PART II. 



10. Variation of Capnlus equilateralis (from above). 



11. Variation of Capulus equilateralis (from side) . 



