Note 266 — ON PARASITES IN GENERAL. (continued 6)
Reading edition
The cercaria is the characteristic larval stage of the Trematodes, and corresponds to a cysticercus or cysticercoid, though there is the important difference that the cercaria has an enteric cavity. According to some observers the enteron is represented by the frontal sucker of some Cestodes, and by the rostellum of the majority of others.
The sporocyst and redia are regarded as intercalated stages, viz., as cercariæ exhibiting pædogenesis, i.e., development of young by a parthenogenetic process from individuals (i.e., cercariæ) not yet adult.