PLATE 80. 
Fig. 1. 346. 3. AvICULA INSUETA. (Pag. 291.) 
1 a. A specimen, natural size. 1b. A portion of the surface enlarged. 
Fig. 2. 347. 4. AvICULA DEMISsSa. (Pag. 292.) 
2a. A large perfect specimen, which is more elevated than usual. 
26. The impression of a smaller specimen in sandstone. 
Fig. 3. 348. 5. AvicuLA? DESQUAMATA. (Pag. 292.) 
3a, A specimen, natural size. 3b. An enlarged portion of the surface. 
Fig. 4. 349. 7. AMBONYCHIA RADIATA. (Pag. 292.) 
4a, 6. The right and left valves of different specimens of this species. 
4c. A smaller individual, with the radii distinctly marked, and more than thirty in number. 
4d. A young specimen, with the radii finely marked. 4e. A portion of the surface enlarged. 
4 f. A cast of the interior of the right valve : the posterior slope shows a straight, well defined, impressed 
line. 
4h. Profile view of a specimen preserving both valves. 
4%. Lateral view of the same. The difference in form between this and the preceding specimens is due to 
pressure. 
47. A large specimen incrusted at its base with a coral, of which an enlarged portion is givenin 4 g. (The 
letter is omitted on some of the plates.) 
4k. Enlarged portion of the surface, showing the same structure as 4 e. 
41. An impression of a part of the valve of a very large and strongly ribbed specimen. 
Fig. 5. 350. 8. AMBONYCHIA CARINATA. (Pag. 294.) 
5 a. Left valve of this species. 
= 
3) 
6. Profile view, showing both valves. The apparent inequality of the beaks is produced by a slight displace- 
ment from pressure. 
