EXPLANATION" OP THE PLATES. .537 



PLATE XVni. 



* Tlie figures marked are left valves. 



JJnionidce. 



Page 



1. "Dnio littoralis, Drap. \. Auvergne 433 



2. {MonocondylcBa) Paraguayanus, D'Orb. \. S. America 434 



3. Castalia ambigua, Lam. \. R. Amazon : 434 



4. Hyria syrmatopliora, Gronov. |. S. Americaf 434 



5.*Iridiila exotica, Lam. I-. Africa, E. Nile 435 



6. Mycetopus soleniformis, D'Orb. 1. S. America, R. Parana 435 



7. -^theria semilunata, Lam. ^. Senegal .• 435 



Chamidce. 



8. Chama macrophylla, Chemn. J. Antilles 437 



9. left valve , 437 



10. Diceras arietinum, Lam. ^. Coral Oolite, France 439 



11. left valve 439 



12. [Requienia) Lonsdalii, J. Sby. \. Neocomian, Spain 



—Brit , 439 



HippuritidcB. 



13. Caprotina striata, D'Orb. TJ. Grreensand, France , , 451 



14. left valve 451 



TridacnidcB. 



15. Tridacna squamosa, Cbem. ^. Bombay 452 



16. Hippopus maculatus. Lam. ^. N. Australia 453 



Cardiadce (part). 



17. Lithocardium aviculare. Lam. \. Eocene, Paris 454 



Cyprinidcs (part). 



18. Cardilia semi-sulcata. Lam. Amboina. 469 



19.*Megalodon cucuUatus, J. Sby. -J. Devonian, Eifel 469 



t The animal of Hyria has two siphonal orifices. 



