EXPLANATION OF PLATE LXIII. 



Figs. 1-4. CYRTIA INEXPECTANS n. sp p. 383 



1. Posterior view showing the cardinal area with covered delthy- 

 ris. A wax impression from the natural mould of the holo- 

 type. 2-4. Posterior, pedicle and lateral views of an im- 

 perfect internal cast of a pedicle valve, the holotype. (W. 

 M., No. 381.) 



Residual chert, Springfield, Missouri. 



Figs. 5-8, SPIRIFERELLA PLENA (Hall) p. 412 



5-7. Pedicle, brachial and posterior views of a nearly perfect 

 specimen. (W. M., No. 7053.) 



Burlington limestone, Quincy, Illinois. 



8. View of the interior of a pedicle valve showing the strongly 



developed dental lamellae. (W. M., No. 7548.) 

 Burlington limestone, Burlington, Iowa. 



Figs. 9-10. SPIRIFERELLA LATIOR n. sp. p. 414 



9. View of a nearly complete pedicle valve, the holotype. (W. 



M., No. 13566.) 



Burlington limestone, Springfield, Missouri. 



10. View of the interior of an incomplete pedicle valve. (W. 

 M., No. 13570.) 



Burlington limestone, Osccola, Missouri. 



142 



