In chapter 2 of lord of the flies who is missing?

At the begining of the chapter, while Ralph and Piggy are bathing in the pool Ralph asked "Where's everybody?" Ralph specifically refers to Samneric and Bill, which would indicate that he believed that there were at least five boys in his group, including himself. Piggy pointed beyond the platform and replied "That's where they have gone. Jack's party." So in fact all that actually remained of Ralph's group were Ralph and Piggy. By the morning after the party, and the killing of Simon, Samneric had rejoined Ralph's group.