PLATE 80. 

 Fig. 1. 346. 3. AvicuLA insueta. (Pag. 291.) 



1 a. A specimen, natural size. 1 b. A portion of the surlace enlarged. 



Fig. 2. 347. 4. AvicuLA DEMissA. (Pag. 292.) 



2 a. A large perfect specimen, which is more elevated than usual. 

 2 b. The impression of a sm:Jler specimen in sandstone. 



Fig. 3. 348. 5. AvicuLA? DESQUAMATA. (Pag. 292.) 



3 a. A specimen, natural size. 3 b. An enlarged portion of the surface. 



Fig. 4. 349. 7. Ambonychia radiata. (P^g- 292.) 



4 a, b. The right and left valves of different specimens of this species. 



4 c. A smaller individual, with the radii distinctly marked, and more than thirty in number. 



4 d. A young specimen, with the radii finely marked. 4 c. A portion of the surface enlarged. 



4/. A cast of the interior of the right valve : the posterior slope shows a straight, well defined, impressed 



line. 

 4 h. Profile view of a specimen preserving both valves. 

 4 i. Lateral view of the same. The difference in form between this and the preceding specimens is due to 



pressure. 

 4 ;'. A large specimen incrusted at its base with a coral, of which an enlarged portion is given in 4 g. ( The 



letter is omitted on some of the plates.) 

 4 k. Enlarged portion of the surface, showing the same structure as 4 e. 



4 /. 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. 



5 h. Profile view, showing both valves. The apparent inequality of the beaks is produced by a slight displace- 

 ment from pressure. 



