A. Guyanensis. The Guiana Ampullaria.
Globular, thick, with unequal longitudinal striæ; covered with brown epidermis; inside golden colour.
A. rugosa. The rough Ampullaria. Pl. [21], fig. 3.
Species dextral.
A. Guinaica. The Guinea Ampullaria.
Species sinistral.
A. carinata. The carinated Ampullaria.
Species sinistral, with a very large umbilicus, spirally carinated.