PLATE 36. 



Fio-. 1. ;208. 9. Modiolopsis aviculoides. (Pag- 161.) 



1 a. A \-iew of the lel't valve nf this specimen. I 6. Dorsal view of the same. 



Fig. 2. 210. 1. AvicuLA TRENTONEKsis. (Pag- 161.) 



2 a. A worn specimen, showing only obscure traces of the radii, with strong concentric ridges. 

 2 b. A similar specimen, with obscure radii, having the anterior wing more extended. 



2 c. 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 ELUPTicA. (Pag. 162.) 



Fig. 4. 212. 1. Ambontchia bellistriata. (Pag. 163.) 



4 a. Lell 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 tlie other, as is clearly shown in the lower 



part of tile figure, and in 4 b, 



4 d. 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 tlie shell, which is beautifully ornamented by radiating and concentric 



strise. 

 .') c Anterior profile view of a single valve. ' 6 rf. A portion of the shell enlarged. 



Fig. 6. 214. 3. Ambonychia amygdalina. (Pag- 165.) 



a. Right valve of tliis 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 tjndata. (Pag. 165.) 



7 a. 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.) 



5 a. Right valve of this species. s b. Profile view from the posterior side. 



Fig. 9. 217. 6. Ambonychia 1 (Pag. 167.) 



y a, b. View nf the single valve, and profile nf the same. 



