84 ruocEKniNGS of the walacological society. 



on the surface of the shell, as its pedestal, secreted by the foot, covers 

 all such irregularities. I cannot help doubting if there is any such 

 connection between the base and the adductors as exists between the 

 latter and the shell. The irregularities of the specimens living on 

 a smooth surface indicate that they are not absolutely fixed to one 

 spot, at least not more than Gadinia or Crepidida wlu'U young. If 

 the adductors were organically attached to the base it would be death 

 to the animal to move." 



I think it has been well worth while giving the above descriptive 

 remarks in extenso for the sake of comparison, if for no other cause. 

 Most probably these two species are descended from a common ancestor, 

 there being so many close points of similitude ; but, while so nearly 

 allied to each other, they are abundantly distinct from the typical 

 section of the genus. 



