KXPI.ANATION OF PLATE VI. 



P.l!;n. 

 CARDIOMOnPHA MlSSOURIENSIS i>T7 



I'ig. 1. View of the riRht valve of a specimen of the usual size auil form. 

 2. Cardinal view of the same iudividual. 



SkDGEWICKIA f CONCAVA 07(; 



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



AVICULOPECTEN CUKTO-CARDINALIS 073 



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

 AVICULOPECTEN Webbrensis 273 



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



AVICULOPECTEN PAKVULUS , O74 



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

 elevated primary rays, with finer ones between. 



MVALINA PeRMIANA 07f, 



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



shows the extreme of other specimens. 



Myai.ina aviculoides 075 



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



showing in the matrix. 



GONIATITES KlNGII 2711 



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 i)roportional size of the volutions and depth of tlie 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 YRTOCER AS CESSATOK 278 



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

 strong annulations. 



Pkntacrinus asteriscus? 280 



Fig. 10. Enlarged view of a disk referred with doubt to this species. The figure is enlarged 

 two diameters. 



Spirifera (Spirikerina?) Alia 281 



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

 Spiriferina Homfrayi! 281 



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

 EdMONDIA MVRl.VA 283 



Fig. 19. View of an imperfect left valve. 



ASTAKTB AREN08A 297 



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



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

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



Tereiiratula Humholdtensis 282 



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

 of the valve. 

 21. Uor.sal valve of another iudividual nearly dostitiite of tlic plications. 



