Ascidians

a-sid′i-anz, n.pl. a group belonging to the tunicate Mollusca, forming a cla of degenerate survivors of ancestral vertebrates, asymmetrical marine animals with a tubular heart and no feet, of a double-mouthed flask shape, found at low-water mark on the sea-beach.— n. Ascid′ium , a genus of Ascidians: ( bot. ) a pitcher-shaped, leafy formation, as in the Nepenthes . [Gr. as kid i on , dim. of askos , a leathern bag, wine-skin.]