Plate XII. 



* Ostrea munsoni sp. nov. 



Tliree figures showing one view of an adult form and two views of 

 medium-sized specimen. The older specimen shows larger valve on top 

 exposing portion of lower valve at pallial margin. Both sides of the 

 smaller specimen are shown, the smaller valve at the up])er right-hand 

 corner of the plate and the larger valve at the lower left-hand corner. 



