EXPLANATION OF PLATE VI. 



Pagp. 

 CAROlOMOIiPHA MlSSOUUIENSIS ,. 277 



Fig. 1. View of the right valve of a specimen of the usual size and form. 

 2. Cardiual view of the same iudividual. 



SkUGEWICKIA ? CONCAVA 276 



Fig. 3. View of a right valve, as obtained by a gutta-percha impressiou in the natural mold. 



AVICULOPECTEN CURTO-CAEDINALIS 273 



Fig. 4. View of the specimen described, enlarged to twice the natural size. 

 AVICULOPECTEN Webeeensis 273 



Fig. 5. View of a left valve, showing the strongly alternating coarser and finer striiB. 



AVICULOPECTEN PAKVULUS .' , 274 



Fig. 6. View of a left valve, enlarged to three times the natural size, showing the strong 

 elevated primary rays, with finer ones between. 



Myalina Permiana 276 



Fig. 7. View of a cast of a right valve, showing the usual form. The outline at the beak 

 shows the extreme of other specimens. 



Myalina aviculoides 275 



Fig. 8. View of an internal cast of a left valve, with the impression of the extended beak 

 showing. in the matrix. 



Goniatites Kixgii. 279 



Fig. 9. Lateral view of a specimen of medium size, showing the deep umbilicus. 



10. View of the opposite side of a similar individual, showing more distinctly the surface- 



markings. 



11. Profile view of the specimen fig. 9, showing the great width of the shell. 



12. Sectional view, showing the proportional size of the volutions and depth of the um- 



bilicus. 



13. Profile view of a smaller iudividual, the outer volutions broken away to reveal the 



lines of septa. 



14. Profile of a septum from the latter, enlarged. 



C yrtoceras cessator 278 



Fig. 15. Lateral view of the specimen described, showing the curvature of the tube and the 

 strong aunulations. 



Pentacrinus asteriscus 1 280 



Fig. 16. Enlarged view of a disk referred with doubt to this species. The figure is enlarged 

 two diameters. 



Spirifera (Spirip^erina?) Alia 281 



Fig. 17. View of a ventral valve, showing the characters described. 

 Spikifekina Homfrayi? 281 



Fig. 18. View of an imperfect dorsal valve referred to this. species. 

 Edmondia Myrina 283 



Fig. 19. View of an imperfect left valve. 

 Astarte arenosa ». 297 



Fig. 20. View of a specimen of a left valve, enlarged. 



21. Viewof a fragment of rock containing several individuals, including the above. The 

 species is placed with some doubt on this plate among the Triassic forms. 



Terebkatula Humuoldtensis , 282 



Figs. 22-23. Dorsal and profile views of a specimen, showing strong plications on the front 

 of the valve. 

 24. Dorsal valve of another iudividual nearly destitute of the plications. 



