PLATE 21, 
Page 
Fig. 1, 2 & 3. Strophodonta cavumbona. 187 
1 a, c. Ventral anti dorsal valves of young specimens. 
1 b, d. The striae in profile, and the surface enlarged. 
1 e. A partial cast of the ventral valve. 
1 /. The dorsal valve partially exfoliated, and showing the crenulations along the hinge-line : 
the striae are rounded and frequently bifurcating. 
1 g. The punctate surface shown where the shell is exfoliated. 
1 h. Profile of the rounded striae of 1 /. 
2 a. The dorsal valve of a well-preserved specimen. 
2 c. Profile of striae, showing the elevations and flat surfaces between them. 
3. A ventral valve, probably of this species. 
Fig. 4. Strophodonta punctulifera. 188 
4 a. A cast of this species. 
4 b. Enlargement of the striae, showing the punctate surface. 
Fig. 5, 6 & 7. Strophodonta leavenwortiiana. 189 
5 a. The dorsal valve, showing obscurely the concentric wrinkles and the punctate surface 
where the shell is exfoliated. 
G a. Interior of the ventral valve. 
6 b. Profile of the preceding. 
6 c. Enlargement of the crenulations of the hinge-line of G a. 
7 a. Interior of a ventral valve. 
7 b. Profile of the same. 
Fig. 8 & 9. Strophodonta radiata. 193 
8 a. A figure of the original specimen, with the shell in part exfoliated. 
8 b. Enlargement of the radiating and concentric striae. 
9 a. A smaller individual from the same locality. 
9 b. Enlargement of surface when the shell is partially exfoliated. 
