The oyster is ovoviviparous; that is, it retains its eggs until they are partly matured.
Some of the dinosaurs may have been ovoviviparous, like some modern serpents.
ovoviviparous: when living young are born from eggs which are hatched in the body of the parent.
Descending a little lower, we come to the oviparous and ovoviviparous tribes.
Coenogonous: oviparous at one season of the year, ovoviviparous at another, as in Aphididae.
Producing eggs that hatch within the female's body. Some fish and reptiles are ovoviviparous. Compare oviparous, viviparous.