PLATE 36. 
Fig. 1. 208. 9. Modiolopsis aviculoides. (Pag- 161.) 
1 a. 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. 
2 6. A similar specimen, with obscure radii, having the anterior wing more extended. 
2 e. The opposite valve of a specimen of similar form as the last. 
2 d. 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.) 
4 a. Left valve of a very symmetrical specimen. 
4 b. Right valve of a larger specimen. 4 c. 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. 
4 (I. 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 b. Left valve, retaining a portion of the shell, which is- beautifully ornamented by radiating and concentric 
striae. 
5 c. Anterior profile view of a single 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 c. Profile of the anterior extremity, showing a kind of lunule below the beaks. 
Fig. 7. 215. 4. Ambonychia undata. 
7 o. Right valve of a specimen which is imperfect on the lower side 
7 b. 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 i. Profile view from the posterior side. 
Fig. 9. 217. 6. Ambonychia? (Pag. 167.) 
9 a, b. View of the single valve, and profile of the same. 
(Pag. 165.) 
