PLATE 16. 
Page 
Fig. 1 - 8, & 16. Strophodonta yaristriata. 180 
1 a. A young individual slightly convex in the centre towards the beak, and flat at the sides. 
1 6. Profile showing the outline from beak to base. 
1 c. Enlargement showing the stronger elevated striae with the finer intermediate ones, and the 
commencement of other stronger ones in the midst of the finer striae 
2. An individual of the same character, having a greater convexity near the beak. 
3 a. A similar form where the beak or umbo is not elevated, and the whole shell nearly flat. 
3 b. Profile showing the curvature of the shell near the base. 
3 c. Enlargement of striae, showing the fasciculate character. 
3 d. A farther enlargement of the surface, showing the concentric striae. 
4 a. An individual having the character of S. rectilateris. 
4 b. Profile of the same. 
4 c. Profile of an individual having similar characters of surface, with a greater convexity. 
4 d. Enlargement of striae of 4 a, showing the alternating size and frequent bifurcation. 
5 a. The S. imprcssa of Conrad, natural size. 
5 b. Profile of same, showing the abrupt bending or geniculation towards the base. 
5 c. Enlargement of striae, showing the coarser ones with intermediate fascicles of smaller 
ones. 
5 d. A portion of the surface enlarged where partially exfoliated on an impression of the 
exterior surface, showing the impressed lines made by the stronger striae; which is mere¬ 
ly a reverse of fig. 5 d, or of fig. 3c & 3 d. 
G, An individual with coarser striaj than usual, the surface partially exfoliated, and profile of same. 
6 a. The striae enlarged, showing the punctate character of the surface when partially exfoliated. 
7 a, b. Illustrations of the surface of “ Lcptcena indent a”. 
8 a, c. Illustration of the hinge-line, area, vascular impression, etc. of the ventral valve, show¬ 
ing the apparent foramen, which is due to fracture, and has not the regular triangular form 
of Strophomena. 
8 b. Enlargement of hinge-line, teeth, etc. of the dorsal valve. 
16. S. varistriata, var. arata. 
Fig. 9 - 12. Strophodonta planulata. 184 
9 a. An individual of medium size, with the hinge-extremities salient. 
9 b. Profile view of the same. 
9 c. Enlargement of the surface, showing the character of the radiating and concentric striae. 
10. An individual showing some faint concentric undulations. 
11 a. A large individual nearly entire, having the exterior surface slightly weathered, and 
showing the puncta along the strite. 
116. Profile of the preceding specimen. 
11c. Enlargement of the surface, showing the character of the striae and arrangement of the 
puncta. 
12. An individual in which the shell is partially removed, showing obscurely the form of the 
vascular impressions. 
Fig. 13 - 15. Strophomena conradi. 
194 
13 a. The ventral valve. 
15. Ventral view of another individual. 
14. Profile view of the same. 
