[99] The classification of the Mollusca adopted in the present chapter is shewn in the subjoined table:
I. ODONTOPHORA.
1. Gasteropoda.
a. Prosobranchiata.
b. Opisthobranchiata.
c. Pulmonata.
d. Heteropoda.
2. Pteropoda.
a. Gymnosomata.
b. Thecosomata.