PLATE 30. 



Fig. 1. 496. 1. Myalina mytiliformis. (Pag. 100.) 



1 a. The right valve of this species somewhat compressed, and having the anterior expansion broken off in 



part. 

 1 b. The right valve of another specimen, less compressed than the preceding. 

 1 c. A specimen preserving both valves, which are partially open along the cardinal line. The lower portion 



of both valves is broken off. 



1 d. The left valve of the preceding specimen, compressed so that it appears much narrower than its natural 



form. 



Fig. 2. 497. 20. MoDioLOPsis ovatus. (^^"- ^^^■) 



2 o. The left valve of a specimen of ordinary size. 



2 b. The right valve (imperfect) of a large individual. 



Fig. 3, & 4 a. 498. 21. Modiolopsis subcaeinatus. (P'^g- ^01-) 



3 o. A young individual of this species. 



3 6, c. The right valves of two individuals of medium size. 



3 d. The left valve of an older individual. 



4 a. This individual has nearly the same form as figs. 3 b and 3 c, but is more compressed, and concentric 



folds arc not at all conspicuous. 



Fig. 4 b. 499. 9. Tellinomya elliptica. ( Pag. 102.) 



Fig. 5. * Cypricakdia? (M. s.). (Pag. 10.9.) 



5 a. View looking upon the cardinal line. 



5 !>. Lateral view of left valve, which is crushed, showing the outline of the right valve beyond. 



