They are both ventricose, thin, inflated shells, with large body-whorls and crenulated lips.
It is much like the Venus shells in form, but the margins are not crenulated.
crenulated: Having a series of notches; marked as with notches, as the indented margin of a shell.
The clouds were in rounded bunches and each bunch was crenulated.
Leaves deltoid, wider than long, crenulated all round, both sides smooth from the first; leafstalk compressed; buds glutinous.