Prosobranchs are the largest subclass of gastropods. Most species are marine, but many freshwater species and a few terrestrial forms are known. Prosobranchs have an operculum (lacking in pulmonates), and most have a spirally coiled shell (in a few, the shell is cup-shaped or tubular). The head includes eyes that are located on tentacles. The mantle cavity is anteriorally directed and near the head.
Prosobranchs include such familiar gastropods as conchs, whelks, limpets, periwinkles, oyster borers, and coweries. They are divided into three Orders, Archaeogastropoda, Mesogastropoda, and Neogastropoda.
Hickman, C.P. and L. S. Roberts. 1994. Animal Diversity. Wm. C. Brown, Dubuque, IA.
Brusca, R. C., and G. J. Brusca. Invertebrates. 1990. Sinauer Associates, Sunderland, MA.
Phil Myers (author), Museum of Zoology, University of Michigan-Ann Arbor.