Incurrent and radial canals are interconnected with the help of prosopyles in syconoid type of sponges. Incurrent canals open outside through dermal ostia and lead into adjacent radial canals through minute openings called prosopyles. In adults, they are simple intercellular spaces. The radial canals open into central spongocoel through internal ostia or apopyles. Spongocoel opens to exterior through an excurrent pore called osculum.