Explanation of Tlate XYIII. 



Page 

 Fig . 1 . Camarocystites obconicu? 132 



Lateral aspect ( 4fcer Meek & Worthen.) 



Silurian, Trenton limestone. 

 Fig. 2. Camarocystites shumardi 132 



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



SiluriaQ, Trenton limestone. 

 Fig 3. Echinodiscus kaskaskiensis 133 



(After Hall.) 



Carboniferous, Kaskaskia limestone. 

 Fig. 4. Peniremites elongatus . . 133 



Lateral aspect. (Keyes collection ) 



Carboniferous, Upper Burlington limestone. 

 Fig. 5. Pentremites conoideus 131 



Side view. (Mns Mo Geol. Sur ) 



Carboniferous, Keokuk limestone. 



Pentremites sulcatus 135 



Side view. (Keyes collection.) 



Same from above. 



Carboniferous, Kaskaskia limestone. 



Cryptobtastus melo 139 



Lateral view. (Iveyes collection.) 



Same from above. 



Carboniferous, Lower Burlington limestone. 



Cryptoblastus kirkivoodensis ; 139 



Side aspect. (Wachsmuth & Springer collection.) 



Same from above. 



Carboniferous, Saint Louis limestone. 



Schizoblastus sayi 138 



Side view. (Kjyes collection.) 



Same from above. 



Carboniferous, Upper Burlington limestone. 

 Fig. 10. Granatocrinus norwoodi 140 



A medium-sized specimen. (Keyes collection.) 



Carboniferous, Upper Burlington limestone. 

 Fig. 11. Metablaslus lintatus 136 



Lateral aspect. (Keyes collection.) 



Carboniferous, Upper Burlington limestone. 

 Fig 12. Metablastus ivortheni 137 



A large specimen. (Keyes collection.) 



Carboniferous, Keokuk limestone. 

 Fig. 13. Metablastus bipyramidalis 137 



Lateral view. (Keyes collection.) 



Carboniferous, Keokuk limestone. 



Fig . 14 . Orophocrinus slelliformis 141 



14a. Top view. (Mns. Mo. Geol. Sur.) 

 14b. Side view of another specimen. 



Cas-boniferous, Lower Burlington limestone. 



Fig. 



6. 





6a. 





6b. 



Fig. 



7. 





7a. 





7b. 



Fig. 



8. 





8a. 





8o. 



Fig. 



9 





9a. 





9b. 



