PLATE 36. 
Fig. tf. 208. 9. Mopiouopsis avICULOIDEs. (Pag. 161.) 
1a. A view of the left valve of this specimen. 1 b. Dorsal view of the same. 
Fig. 2. 210. 1. AvicULA TRENTONENSIS. (Pag. 161.) 
2 a. A worn specimen, showing only obscure traces of the radii, with strong concentric ridges. 
26. A similar specimen, with obscure radii, having the anterior wing more extended. 
2c. The opposite valve of a specimen of similar form as the last. 
2d. A large specimen of the left valve, with strong radii. 
Fig. 3. 211. 2. AvicuLA ELLIPTICA. (Pag. 162.) 
Fig. 4. 212. 1. AMBONYCHIA BELLISTRIATA. (Pag. 163.) 
4a. Left valve of a very symmetrical specimen. 
46. Right valve of a larger specimen. 4c. Profile view of the same. The specimen appears to be inequi- 
valve, which is due to the sliding down of one valve below the other, as is clearly shown in the lower 
part of the figure, and in 4 b. 
4d. A portion of the surface enlarged, showing the fine undulating striae, crossed by the concentric lines of 
growth. 
Fig. 5. 213. 2. AMBONYCHIA ORBICULARIS. (Pag. 164.) 
5 a. Right valve of a specimen, showing the muscular impression. 
5 6. Left valve, retaining a portion of the shell, which is beautifully ornamented by radiating and concentric 
striz. 
5 e. Anterior profile view of a singte valve. 6 d. A portion of the shell enlarged. 
Fig. 6. 214. 3. AMBONYCHIA AMYGDALINA. (Pag. 165.) 
6 a. Right valve of this specimen. 6 b. Profile from the posterior side. 
6 ec. Profile of the anterior extremity, showing a kind of lunule below the beaks. 
Fig. 7. 215. 4. AMBONYCHIA UNDATA. (Pag. 165.) 
7 a. Right valve of a specimen which is imperfect on the lower side. 
7b. Profile of the same, looking upon the posterior side. 
Fig. 8. 216. 5. AMBONYCHIA OBTUSA. (Pag. 167.) 
8 a. Right valve of this species. 8 b. Profile view from the posterior side. 
Fig. 9. 217. 6. Amsonycuta? (Pag. 167.) 
9 a, b. View of the single valve, and profile of the same. 
