Two dark heads kept in advance of the others. "Madge," warned a voice, "we must not go too far out. Remember, we promised Jenny Ann. My, but isn't this water glorious! I feel as though I could swim on forever." A graceful figure turned over and the moonlight shone full on a happy face. The two swimmers moved along more slowly. "Nellie, Lillian!" Madge called back, "are you all right? Do you wish to go on farther?" Phil and Madge floated quietly until their two friends caught up with them. "I feel as though I could go on all night at this rate," declared Lillian Seldon. Eleanor put her hand out. "May I float along with you a little, Madge?" she asked. "I am tired. How wide and empty the ocean looks to-night! We must not get out of sight of the lights of the 'Merry Maid'." "There is no danger!" scoffed Madge. "Look out!" cried Phil Alden sharply. She was swimming ahead. She saw first the sails of a small yacht making across the bay with all speed to the line of the shore that the girls had just quitted. "Let's follow the boat back home," suggested Madge. "We can keep far enough away for them not to see us. It will be rather good fun if they take us for porpoises or mermaids, or any other queer sea creature." "Don't run into that Noah's ark that we saw anchored in the creek this morning, Roy," came a shrill voice from the deck of the yacht. "I saw half a dozen women going aboard her this afternoon laden with boxes and trunks--everything but the parrot and the monkey. It looked as though they meant to spend the summer aboard her." "Perhaps they do, Mabel," a man's voice answered. "The 'Noah's Ark' is a houseboat. It looked very tiny for so many people, but I thought it was rather pretty." "Well, we have girls enough at Cape May this summer--about six to every man," argued Mabel crossly. "I vote that we give these new persons the cold shoulder. Nobody knows who they are, nor where they come from. It is bad enough to have to associate with tiresome hotel visitors, but I shall draw the line at these water-rats, and I hope you will do the same." "She means us," gasped Eleanor. "What a perfectly horrid girl!" The high, sharp voice on the yacht was distinctly audible over the water. The boat had slowed down as it drew nearer to the shore. "Swim along with Phil, Nellie," proposed Madge. "I am going to have some fun with those young persons. I don't care if I _am_ nearly grown-up; I am not going to miss a lark when there's a chance. I have that rubber ball that Phil and I brought out to play with in the water. Watch me throw it on their yacht. They'll think it's a bomb, or a meteor, if I can throw straight enough. I am going to settle with them this very minute for the disagreeable things they just said about us and our pretty 'Merry Maid.'"