Urnatella, [490], [493], [518]

Urobenus, [388]

Uteriporus, [42]

Uterus, of Leptoplana, [8], [14];

of Planaria, [38], [39];

of Triclads, [40];

of Rhabdocoela, [48];

of Temnocephala, [54];

of Polystomum, [57], [59];

of Diplozoon, [60];