PLATE XVIII 



PAGE 



Figs. 1, 2. RINGICULA CLARKI Gardner n. sp 400 



1. Dorsal view. X 3. 



2. Ventral view. X 3. 



Monmouth formation, Brightseat, Prince George's County. 



Figs. 3, 4. ACTEOX LINTELS (Conrad) 397 



3. Dorsal view. X 3. 



4. Ventral view. X 3. 



Monmouth formation, Brightseat, Prince George's County. 



Figs. 5, 6. AVELLAXA PIXGUIS Gardner n. sp 406 



5. Dorsal view. X 2. 



6. Ventral view. X 2. 



Monmouth formation, Brightseat, Prince George's County. 



Fig. 7. AVELLAXA I.IXTOXI Gardner n. sp 406 



Dorsal view. X 2. Monmouth formation, 2 miles southwest of Oxon 

 Hill, Prince George's County. 



Figs. 8, 9. HAMIXEA CYLIXDRICA Gardner n. sp 409 



8. Ventral view. X 2. 



9. Dorsal view. X 2. 



Monmouth formation, Brightseat, Prince George's County. 



Figs. 10, 11. CYLTCIIXA RECTA Gabb 411 



10. Ventral view. X 3. 



11. Dorsal view. X 3. 



Monmouth formation, Brightseat, Prince George's County. 



Fig. 12. MORKA XATICELLA Gabb 465 



Squeeze of mold of exterior. Matawan formation, locality unknown. 



Fig. 13. MOREA MARYLAXDICA Gardner n. sp 466 



Ventral view. X 2. Monmouth formation, 2 miles southwest of Oxon 

 Hill, Prince George's County. 



Figs. 14, 15. PALADMETE CANCELLARIA (Conrad) 413 



14. Ventral view. X 2. 



15. Dorsal view. X 2. 



2y 2 miles south of Dumas, Texas, U. S. National Museum. 



