PLATE 22. 
Page 
Fig. 1 a - t. Strophodonta beckii. 191 
1 a. A young individual in which no corrugations are developed. 
1 b, c. Two specimens exhibiting the extremes of form in the extension of the hinge-line, and 
showing the beginning of the development of the corrugations. 
1 d. A specimen showing the corrugations more strongly. 
1 e. An individual of full size, in which the corrugations are well developed. 
If, g. Dorsal and ventral sides of an entire individual. 
1 h. Profile view of the preceding specimen. 
1 i. An old specimen where the corrugations are much stronger and closer than usual. 
1 k, l, m. The interiors of several ventral valves, showing the area, crenulated hinge-line, 
muscular and vascular impressions, etc. 
1 n. Area of the ventral valve. 
1 o, p. Enlargement and profile of the striae. 
1 r. A portion of the area enlarged, showing the striated surface and crenulated margin. 
1 s, t. Portions of the casts of the ventral valves of two different individuals, showing some 
slight difference in the character and strength of the impressions. 
