shows. Shell-less slugs have the mantle fully visible. The dorsal surface of the mantle is called the notum, while the ventral surface of the mantle is called the hyponotum. In the family Philomycidae, the mantle covers the whole back side of the body. See also Mollusc shell, which is formed by the mantle Siphon, which is a part of the mantle in some groups of molluscs References Mollusc anatomy Cephalopod zootomy