Final answer:
The two larval stages of barnacles are the nauplius larva and the cypris larva.
Step-by-step explanation:
The two larval stages in the life cycle of barnacles are the nauplius larva and the cypris larva. The nauplius larva is the first larval stage, characterized by three pairs of appendages for swimming. The cypris larva is the final larval stage, which has developed into a fully formed juvenile barnacle ready to settle and attach to a substrate.