If one slaughters a wild animal or a bird, but it is found to be terefah, then Rabbi Meir requires him to cover the blood, but the Sages exempt him. Why do the Sages exempt him? Because it is unfit slaughter, and it is not called slaughter at all. But this is Rabbi Shimon! Then why is he called "Sages" here, but back then in discussing the laws of "it and its offspring" he is called Rabbi Shimon, and there Rabbi Meir is called the Sages? That is because Rabbi Yehudah the Prince, the compiler of the Mishnah, agreed with Rabbi Shimon here, but agreed with his opponent, Rabbi Meir, over there. By ascribing an opinion to "the Sages" Rabbi Yehudah was indicating what he thought the law should be.
Art: Winslow Homer - The Dinner Horn