INDEX TO THE GENERA.

Referring to Plates and Figures.

Achatina, [XXIV.] 24.

Aclis, [XIV.] 23, 25.

Acmæa, [X.] 22, 23.

Acme, [XXIV.] 26.

Adeorbis, [XI.] 25.

Akera, [XX.] 16.

Amphispira, [XX.] 14, 15.

Ancylus, [XXI.] 14-17.