Explanation of Plate XVIII. 



Fig. 1. Camarocystites obconicus 132 



Lateral aspect (Afcer Meek & Worthen.) 



Silurian, Trenton limestone. 

 Fig. 2. Camarocystites shumardi 132 



Basal view of large specimen. (After Meek and. Worthen.) 



Silnriao, Trenton limestone. 

 Fig 3. Echinodiscus kaskaskiensis 133 



(A-fter Hall.) 



Carboniferous, Kaskaskia limestone. 

 Fig. 4. Peniremites elongalus. . '. 133 



Lateral aspect. (Keyes collection ) 



Carboniferous, Upper Burlington limestone. 

 Fig. 5. Pentremites conoideus 134 



Side view. (Mus Mo Gsol. Sur.) 



Carboniferous, Keokuk limestone. 



Pentremites sulcatus 135 



Side view. (Keyes collection.) 



Same from above. 



Carboniferous, Kaskaskia limestone. 



Cryptoblastus melo 139 



Lateral view. (Ei eyes collection.) 



Same from above. 



Carboniferous, Lower Burlington limestone. 



Cryptoblastus kirkiuoodensis 139 



Side aspect. (Wachsmuth & Springer collection ) 



Same from above. 



Carboniferous, Saint Louis limestone. 



Schisoblastus sayi 138 



Side view. (Keyes collection ) 



Same from above. 



Carboniferous, Upper Burlington limestone. 



Granntocrinus norwoodi 140 



A medinm-sized specimen. (Keyes collection.) 



Carboniferous, Upper Barlington limestone. 



Metablastus lineatus 136 



Lateral aspect. (Keyes collection.) 



Carooniferous, Upper Barlington limestone. 



Metablastus ivortheni 137 



A large specimen. (Keyes collection.) 



Carboniferous, Keokuk limestone. 



Metablastus bipyramidalis 137 



Lateral view. (Keyes collection.) 



Carboniferous, Keokuk limestone. 



Orophocrinus stelliformis 141 



Top view. (Mus. Mo. Geol. Sur.) 



Side view of another specimen. 



Carboniferous, Lower Burlington limestone. 



Fig, 



6. 





6a. 





6b. 



Fig. 



7. 





7a. 





7b. 



Fig. 



8. 





8a. 





80. 



Fig. 



9 





9a. 





9b. 



Fig. 



10. 



Fig. 



11. 



Fig 



12. 



Fig. 



13. 



Fig. 



14. 





14a, 





14b 



