PLATE 27. 



Fig. la, b. 472. 6. Avicula emacekata. ( Pag. 83.) 



Fig. 2. 473. 7. Avicula rhomboidea. (Pfig- SI.) 



2 a. A large individual, in which the anterior wing is loss prominent than usual. 

 2 6. A smaller specimen. 



2 e. A young specimen, having the length nearly equal to the height. 



2 d. The posterior portion of another specimen, having the strise more perfectly preserved and the angle of 

 the wing more extended. 



Fig. 3, 12. 480. 1. Pyrenobiceus cuneatus. ( Pag. 87.) 



3. This specimen, though differing to some extent inform, I have referred to the same species. It retain.s 

 the shell, which is thintly striated, the beak remarkably elevated, and the anterior extremity abruptly 

 rounded. 



12 a, b. The casts of opposite valves of specimens nearly of the same size. 



12 c. The cast of a large individual, showing several prominent folds parallel to the lines of growth. 



Fig. 4. 479. 1. PosiDONiA? alata. ( Pag. 87.) 



Fig. 5, 6. 474. 19. Modiolopsis subalatus. (Pag. 84.) 



6. A fragment of slate, with figures of the right and left valve. 

 6 a, b. Figures of the right valve of two specimens of Large size. 



Fig. 7. 475. 6. Tellinomya lata. ( Pag. 85.) 



Fig. 8, 9. 476. 7. Tellinomya MACHiERiFORMis. (Pag. 85.) 



8 a. The left valve of an individual of ordinary size. 8 6. The right valve of a large individual. 



8 c. The right valve of a smaller individual. 



8 d. A small portion of the surface much enlarged, showing the concentric strise. 

 9. (Cypricardia angvsta, Geol. Kep. 4th District, pag. 76, fig. 6.) 



Fig. 10, 13. 477. 8. Tellinomya curta. (Pag. 86.) 



Fig. 11. 478. 4. Orthonota ctjrta. ( Pag. 86 ) 



11 a. The right valve of a specimen of natural size and proportions. 

 11 6. A specimen of the left valve, narrowed by pressure. 



