Regents of the University of Michigan
Animal Diversity Web: Phylum Mollusca (Mollusks)
A great, detailed description of mollusks. Discusses parts of their external and internal anatomy and their functions, and lists several characteristics of mollusks. Tabbed pages include pictures, specimens and classification.
Regents of the University of Michigan
Animal Diversity Web: Gastropods
An overview of the many types of gastropods, slugs and snails found around the world. Included is a large bank of photos of the various species and their classification information.
Other
Wonders of the Sea
Good general description of the phylum with subordinate descriptions in each of the classes.