Pteropoda
in zoölogy, a class of Cuvier's embranchement of sub-kingdom Mollusca. Also, a sub-class of Cephalopoda, in which the mid-region of the foot is drawn out into a pair of winglike muscular lobes, used as paddles. The hind region is often absorbed, but may carry an operculum; the fore region provided with suckers. There are two is sometimes drawn out into tentacles, orders: Thecosomata and Gymnosomata.