137 



With his description our shell most accurately cor- 

 responds in every particular. " Shell smaller than 

 a barley-corn, oval oblong and rather acute, with a 

 small umbilicus, and the aperture margined." 

 By the term margined, as applied to the aperture, 

 it is here meant, as in some other places, that the 

 margin is continued all round, and not interrupted 

 by the convexity of the penultimate volution. 



In ditches and canals, but very rarely. 



