Gymnolsemata, the sub-class of Bryozoa belonging to the group Ectoprocta (q.v.), including the three most important orders, the Cyclostomata (q.v.), Ctenostomata (q.y.), and Cheilostomata (q.v.). The main character of the sub-class is that the arms around the mouth are arranged in a circle instead of a horse-shoe, as is the Phylactoleemata. With the exception of the one genus Paludicella, they are all marine.