A subclass of Platyhelminthes comprised of parasitic flatworms characterized by displaying digenesis or by having alternation of generations.
Organisms belonging to this group usually have two suckers, one ventral and the other one oral. They are generally parasitic and the adult forms are common in the digestive tract of their vertebrate hosts. Many species are known to occur in human hosts. These species may be divided into schistosomes (Schistosoma spp.) and non-schistosomes (e.g. Fasciola hepatica).
Word origin: From Dis – double, Genos – race