1. Eight species of Cuban bat trematodes have been examined, and their excretory system established. 2. In Urotrema scabridum Braun a small V-shaped excretory bladder and the flame cell formula 2[(2+ 2+2) + (2+2+2)] were ascertained. This enabled us to affiliate the family Urotrematidae to the Microphalloidea sensu Odening (1964) within the suborder Plagiorchiata. A new key to the families of the Microphalloidea is given. 3. The genus Ochoterenatrema characterized by a pseudogonotyl is divided into the two subgenera Ochoterenatrema (with pretesticular vitellaria) and Morenodendrium n.subgen. (with posttesticular vitellaria). Both subgenera have a V-shaped excretory bladder and the flame cell formula is 2[(2+2+2) + (2+2+2)], as stated for the species O. (O.) diminutum (Chandler) and O. (M.) pricei (Pérez Vigueras) n.comb. 4. Keys for determinating all known species are given together with the description of a Parabascus and two Postorchigenes species. The flame cell formulas tally with all the hitherto known formulas of both genera: 2[(2+2+2) + (2+2+2)]. 5. The species Limatulum solitarium Pérez Vigueras is regarded preliminarily as valid, all Cuban findings of Limatulum are attributed to it. The flame cell formula is 2[(2+2+2)+(2+2+2)]. 6. In the fish-eating bat Noctilio leporinus mastivus a Pygidiopsis species (Heterophyidae) occurs, the flame cell formula of which is 2[(2+2+2) + (2+ 2+2)].