EXPLANATION OF PLATES. 



PLflTB 23. PAGE 



PENTREMITUS ALTUS, N. Sp. (Rowley.) 64 



FIG. 1. — Side view of the type speeimen. 

 FIGS. 2-3. — Side and ventral views of a specimen, 

 doubtfully referred to this species. 



AOROCRINUS CASSEDAYI. Lyon. Rowley. 65 



FIG. 4. — Side view of a broad speeimen. 

 FIG. 5. — Anal view of a longer specimen. 



AOCROCRINUS CASSEDAYI. Var. Ctarkstownensis, 65 



N. Var. (Rowley.) 



FIG. 6. — Basal view of the type specimen. 



AOROCRINUS DEPRESSUS, N. Sp. (Rowley.) 65 



FIG . 7. — Basal view of the type specimen. 



STROPHOSTYLUS AMPLUS, N. Sp. (Rowley.) 66 



FIG. 8. — Side view of the type specimen. 



NATICOPSIS DUBIA, N. Sp. (Rowley.) 66 



FIGS. 9, 10-11. — Side and top views of the type specimen. 



PLATYSTOMA NIAGARENSIS. HaU. Rowley. 67 



FIG. 12. — Side view of a 4ev<^y coiled specimen. 



SPIRIFERINA HORIZONTALIS. N. Sp. (Rowley.) 67 



FIGS. 13-14. — Brachial and pedical views »£ the type 

 specimen. 



FIG. 1.5. — Side view of the same to show the horizon- 

 tal character of the cardinal area. 



FIG. 36. — View of the inside of the pedical valve. 



