in a cave
Percival Clarke's birth name is Perceval Clark.
Percival Gibson was born in 1893.
Thomas Percival was born in 1740.
Percival Ewens died in 1961.
Percival Hussey died in 1944.
After the boy's had mocked Percival's report of seeing the beast, by telling him no large animal could live on such a small island, Percival gave them pause for thought when he told them that the beast came from the sea.
in a cave
Percival is unable to respond to Jack's question about the beast due to his state of shock and trauma. He only cries and cannot provide a coherent answer.
When Percival speaks, he is unable to remember where the beast comes from and becomes overwhelmed with fear. He struggles to articulate his thoughts and eventually breaks down due to the intensity of his emotions.
He says in comes out of the ocean at night. :P
the sea
His address.
Phil & percival (pages 84, 86, & 88)
Percival Wemys Madison (one of the littluns) first says the beast comes from the water.
in a house
Percival says that the beast comes from the sea. To help the whole situation, at this point the boys see a shark out in the water. Maurice pipes up that his dad said there are still unknown creatures in the sea. Then Maurice unhelpfully adds that it could be a squid. All the boys start arguing about whether a squid can come on land or not until Ralph silences everyone.
During the assembly in chapter 5 Ralph attempts to settle the issue of the beast once and for all and convince the boys that it does not exist. He has two littluns who claim to have seen it brought forward. The littun Phil's claims to have seen the beast are quickly dismissed, as it seems likely that he simply mistook Simon for the beast. Unfortunately Ralph's plan backfires when Percival Wemys Madison is told that there is nowhere on the island that a beast could hide he drops a bombshell. Speaking through Piggy and then Jack he tells the boys that the beast comes from the sea.