PLATE XIII 



PAGE 



Figs. 1, 2. POLYNICES (EUSPIKA) HALLi (Gabb) 499 



1. Dorsal view. 



2. Ventral view. 



Monmouth formation, 2 miles southwest of Oxon Hill, Prince 

 George's County. 



Figs. 3, 4. AMAUROPSIS COMPACTA Gardner n. sp 504 



3. Dorsal view. X 3. 



4. Ventral view. X 3. 



Monmouth formation, McNeys Corners, Prince George's 

 County. 



Fig. 5. MARGARITES ELEVATA Gardner n. sp 506 



Dorsal view of internal cast. X 5. Monmouth formation, Brightseat, 

 Prince George's County. 



Fig. 6. MARGARITES DEPRESSA Gardner n. sp 505 



Ventral view of internal cast. X 5. Monmouth formation, Brightseat, 

 Prince George's County. 



Fig. 7. SOLARIUM MONMOUTHENSIS Gardner n. sp 494 



View of spire. X 2. Monmouth formation, 2 miles southwest of Oxon 

 Hill, Prince George's County. 



Fig. 8. GYRODES PETROSUS (Morton) Gabb 496 



Dorsal view of internal cast with adhering portions of shell. Mon- 

 mouth formation, Brightseat, Prince George's County. 



Fig. 9. EUTREPHOCERAS DEKAYi (Morton) Hyatt 372 



Lateral view of young individual. Monmouth formation, Brooks' 

 Estate near Seat Pleasant, Prince George's County. 



Fig. 10. SPHEXODISCTJS LOBATUS (Tuomey) Meek 388 



Lateral view of one of the earlier whorls. X 2. Monmouth formation, 

 Brightseat, Prince George's County. 



