EXPLANATION OF THE PLATES. 537 
PLATE XVIII. 
* The figures marked are /eft valves. 
Unionide. 
Page 
1. Unio littoralis, Drap. }. Auvergne ....... Gedepbdoceann 108 
2. —— (Monocondylea) Paraguayanus, D’Orb. 4. S. America 434 
aeearala ambigua, lam. 24. RK. Amazon......2 seeecnesen 434 
4, Hyria syrmatophora, Gronov. 3. S. Americaf .......... 434 
peeladina exotica, Lam. 4%. ‘Africa, R. Nilo .....0....08005 435 
6. Mycetopus soleniformis, D’Orb. 2. S. America, R. Parana 435 
7. Aitheria semilunata, Lam. 4. Senegal ..........cceeeeee 435 
Chamide. 
8. Chama macrophylla, Chemn. }. Antilles ...........:.... 437 
9. —— left valve wrrveccecees i ayeveletarateveree lees SOM 
10. Diceras arietinum, Lam. 4. Coral Oolite, France ........ 439 
11. —— ————\§_ eft valve. ..recceseseccesccevsseescsess 439 
12, (Requienia) Lonsdalii, J. Sby. 4. Neocomian, Spain 
—Brit. iasdon oomucnsopaauases Geel trond O tecid Cloiso-d'O es 439 
Hippuritide. 
23, Caprotina striata, D’Orb. U. Greensand, France .......... 451 
14, WEG OGUBE. tin Me atc re S che atss 6 aise alti herde oReeiee 451 
Tridacnide. 
15. Tridacna squamosa, Chem. 3. Bombay.................. 452 
16. Hippopus maculatus, Lam. 4. N. Australia.............. 452 
Cardiade (part). 
17. Lithocardium aviculare, Lam. }. Eocene, Paris.......... 454 
Cyprinide (part). 
18: Cardilia semi-sulcata, Lam. Amboina.........cesee.--se 469 
19 *Megalodon cucullatus, J. Sby. 3. Devonian, Hifel........ 469 
j The animal of Hyria has two siphonal orifices. 
