( n. pl. )
The highest division, or subclass, of gastropod mollusks, including those that have the gills situated anteriorly, or forward of the heart, and the sexes separate.
( n. pl. )
The highest division, or subclass, of gastropod mollusks, including those that have the gills situated anteriorly, or forward of the heart, and the sexes separate.
Webster's Revised Unabridged English Dictionary. Пересмотренный полный словарь английского языка Webster. 2012