In the past, the use of terminology when describing parasitic twins has been somewhat inconsistent. By definition, a parasitic twin is joined to another twin in a certain anatomical location or position on the developed twin's body. The underdeveloped twin is termed the parasite, and the developed twin is termed the autosite. The autosite can have some abnormalities, as well. For the most part, however, it has developed enough that it can live on its own.
Craniopagus parasiticus
Gnathostoma spinigerum
Ancylostoma tubaeforme
Gongylonema pulchrum
Echinostoma revolutum
Dracunculus medinensis
Fannyhessea vaginae
Brachyspira pilosicoli