170 EXPLANATION OF PLATES. 



PLATE VII. 



Fig. 1.— EXOGYRA AEIETENUM. 



Fig. 1 a. Upper valve, exterior view. 

 1 h. Upper valve, interior. 

 1 c. Lower valve. 



1 d, e. Two views, same specimen. 



FiQ. 2.— EXOGTKA FOLIACEA. 



Fig. 2 a. Upper valve, exterior surface. 



2 b. Upper valve, interior surface. 



Fw. 3.— GEYPHiEA PITCHEEI. 



Fig. 3 a. Lower valve, exterior surface. 



3 b. View of upper side of shell, with valves attached. 

 3 c. Profile of large valve. 



3 d. Large valve, variety navia. 

 3 /. Upper valve, exterior view. 



3 g. Upper valve, interior view. 



FiQ. 4.— GRYPILEA L^:;VIUSOirLA. 

 Fig. 4 a. Lower valve. 



4 b. Profile of same. 



PLATE VIII. 



Fig. 1.— EXOGYRA MATHERONIANA. 

 Fig. 1 a. Lower valve. 



1 b. Anterior view. . . 



Fm. 2.— EXOGYRA FRAGOSA. 



Fig. 2 a. Lower valve, exterior view. 



2 b. Lower valve, interior view. 



Fso. 3.— EXOGYRA TEXANA— varietj. 



PLATE IX. 



Fig. 1.— EXOGYRA COSTATA— variety. 



Fig. 1. Exterior view of specimen fig. 3 of the preceding plate. 



Fio. 2.— EXOGYRA COSTATA. 



Fig. 2 a. Exterior view of lower valve. 

 2 b. Interior of lower valve. 



PLATE X. 



Fia. L— EXOGYRA COSTATA. 

 Fig. 1. Exterior view of the lower valve, showing the obsolescent character of the costae. 



