66 



4. Two tiles with young oysters in second year. 



5. Two tiles after " detroquage " or separation 



of the young oyster from the tile. 



6. Series of young oysters a few months old 



adhering to various shells. 



7. Series of young oysters 1 year old. 



8. Series of young oysters 2 years old. 



9. Series of marketable Dutch oysters. 

 10. Series of very large old Dutch oysters. 



IT. III. Oyster Bearing and Fattening at Mar- 

 ENNES, in west of France. 



1. Series of green oysters from Marennes. 



2. Photographs of the " Claires " at Marennes. 



3. Specimens of the vegetation from the Claires 



(consisting of Cladopliora and other Algoe 

 covered with Diatoms, &c.). 



4. Specimens of the deposit from the floor of 



the Claires. 



H. IV. Diseased Conditions, and Experiments on 

 Oysters and other Shell-fish. 



1. Oysters shells eaten into by the Sponge 



Gliona celata. 



2. Oyster shells completely buried in the Sponge. 



3. Oyster shells with mud between laminae of 



shell. 



4. Injured oyster shells. 



5. American oyster from Fleetwood suffering 



from the green disease. 



6. A normal healthy green Marennes oyster for 



comparison with the last. 



7. Oysters which have been trephined in order to 



investigate the green disease. 



