<Ul> <Li> Histotrophic viviparity: the zygotes develop in the female's oviducts, but find their nutriments by oophagy or adelphophagy (intra-uterine cannibalism of eggs or sibling embryos in some sharks or in the black salamander Salamandra atra). </Li> <Li> Hemotrophic viviparity: nutrients are provided by the female, often through some form of placenta . In the frog Gastrotheca ovifera, embryos are fed by the mother through specialized gills . The skink Pseudemoia entrecasteauxii and most mammals exhibit a hemotrophic viviparity . </Li> <Li> Placental viviparity is arguably the most highly developed form of viviparity . Placental mammals, including humans, are the best - known example, but adaptations in some other animals also have incorporated this principle or close analogies . Other examples include some species of scorpions and cockroaches, certain genera of sharks and snakes, and velvet worms . </Li> <Li> Ovoviviparity, a less developed form of viviparity, occurs in most vipers, and in most live - bearing bony fishes (Poeciliidae). However, the term is poorly and inconsistently defined, and may be obsolete . </Li> </Ul> <Li> Histotrophic viviparity: the zygotes develop in the female's oviducts, but find their nutriments by oophagy or adelphophagy (intra-uterine cannibalism of eggs or sibling embryos in some sharks or in the black salamander Salamandra atra). </Li> <Li> Hemotrophic viviparity: nutrients are provided by the female, often through some form of placenta . In the frog Gastrotheca ovifera, embryos are fed by the mother through specialized gills . The skink Pseudemoia entrecasteauxii and most mammals exhibit a hemotrophic viviparity . </Li> <Li> Placental viviparity is arguably the most highly developed form of viviparity . Placental mammals, including humans, are the best - known example, but adaptations in some other animals also have incorporated this principle or close analogies . Other examples include some species of scorpions and cockroaches, certain genera of sharks and snakes, and velvet worms . </Li>

The angus fragile is an example of vivipary