PLATE 59. 
Fig. 1. 472. 6. Avicula emacerata. ( Pag. 282.) 
1 a. A young individual of this species, having the radiating and concentric striae equally developed. 
1 b. A larger individual : this one is about the ordinary size of the specimens obtained. 
1 c. A large individual, preserving the surface markings in a good degree of perfection. 
1 d. The right valve of this species, showing the plain nearly flat body of the shell, and striated wing. 
1 e. An enlargement of a portion of the surface, showing the character of the diverging and concentric striae. 
Fig. 2. 644. 8. Avicula undata. (Pag. 283.) 
Fig. 3. 645. 9. Avicula subplana. (Pag. 283.) 
3 a. A left valve of ordinary size, where the extremity of the cardinal line is extended slightly beyond the 
width of the shell. 
3 6. A larger shell, where the cardinal line is less extended than the width of the shell. 
3 c. A fragment of shale with the right valves of two individuals, showing a greater extension of the cardinal 
line, and a more distinct wing than in the left valve. 
Fig. 4. 
646. 
10. 
Avicula? orbiculata. 
(Pag. 284.) 
Fig. 5. 
647. 
2. 
POSIDONOMYA? RHOMBOIDEA. 
(Pag. 284.) 
Fig. 6. 
6 a. 
648. 
The shell, natural size. 
22. 
Modiolopsis? undulostriata. 
6 6. A portion of the surface enlarged. 
(Pag. 284.) 
Fig. 7. 
474. 
19. 
Modiolopsis subalatus? 
(Pag. 285.) 
Fig. 8. 
478. 
4. 
Orthonota curta? 
(Pag. 285.) 
