EXPLANATION OF PLATE 63 

 All figures approximately natural size 

 Fig. 1. Zirphaea dentata Gabb. View of left valve. Longitude, 109 mm. 

 Fig. 2. Zirphaea dentata Gabb. Dorsal view of same specimen as figure 1. 

 Fig. 3. Mya dickersoni, n. sp. Eight valve. Longitude, 56 mm. 

 Fig. 4. Mya dickersoni, n. sp. Left valve. Longitude, 51 mm. 



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