EXPLANATION OF PLATE XL. 



Page 



FIG. 1. Spirifera marionensis 78- 



la. Dorsal aspect. (Mus. Mo. Geol. Sar.j 



Ib. Same of another specimen. (Same cabinet.) 



Carboniferous? Louisiana, (Kinderhook) limestone. 



FIG. 2. Spirifera keokuk 81 



Dorsal view . (Keyes collection . ) 



Carboniferous, Keokuk limestone. 

 FIG. 3. Spirifera forbesi 80 



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



Carboniferous, Burlington limestone. 



FIG. 4. Spirifera parryana 77 



4a. Ventral aspect. 



4b. Djrsal view of same. 



Devonian, Hamilton limestone. 



FIG. 5. Spirifera camerata 8S 



5a. Dorsal view. 

 5b. Dorsal aspect. 

 5c. Ventral valve. 



Carboniferous, Coal Measures. 



FIG 6. Spirifera lineatoides 80 



Dorsal aspect of an exfoliated specimen. (Mas. Mo. Geol. Sur ) 

 Carboniferous, Burlington limestone. 



FIG. 7. Spirifera sp .? 



Dorsal aspect. (Keyes collection.) 



Carboniferous, Kinderhook shales. 

 FIG. 8. Syringothyris plenus 88 



Side vie w . ( Keyes collection . ) 



Carboniferous, Burlington limestone. 



FIG. 9. Spiriferim kentuckensis 86 



9a. Posterior view. 

 9b. Ventral view. 



Carboniferous, Coal Measures. 



FIG. 10. Syringothyris carteri 87 



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

 Carboniferous, Burlington limestone. 



