Wikipedia
Tricladida
Tricladida (triclads) is an order of turbellarians, a group of free-living flatworms. They are also known as planarians, although this common name is also used for a wide number of free-living platyhelminthes.
The triclads are characterized by triply branched intestine and anteriorly situated ovaries, next to the brain.
Today the order Tricladida is split into three suborders, according to their phylogenetic relationships: Maricola, Cavernicola and Continenticola. Formerly, the Tricladida was split according to habitats: Maricola, which is marine; Paludicola, which inhabits freshwater; and Terricola, which is land-dwelling.