PLATE 18 . 
Fig. 1 a - i. Strophodonta yaristhiata, var. arata. 
1 a - d. Ventral valves of several specimens where the shell is more or less exfoliated, the last 
one being almost free from adhering shell. 
1 e,f, g. Profile views, showing the convexity of several individuals. 
1 h. The surface showing the ridges and striae. 
1 i. A portion of a cast of the interior, which preserves the ridges, but shows no intermediate 
striae. 
Fig. 2. Lept^ena concava. 
2 a, b. Ventral and dorsal views of a specimen of this species. 
2 e, d. Profile and cardinal views. 
2 e. Enlargement of area, foramen, etc. 
‘If. Enlargement of the surface, showing the finer longitudinal and concentric striae. 
Fig. 3. Strophomena radiata. 
3 a. The ventral valve. 
3 b, c, d, e. Oasts of specimens of this species. 
