You have tracked down the second of several rabbit holes in this class. When you receive this message, send an e-mail to Dr. Delwiche with the words "Rabbit Hole #2 located" as the subject. At that point, he will forward more details about the extra credit assignment linked to this rabbit hole.
Typically, the rabbit holes will point toward short extra credit activities. Credit for locating these rabbit holes and completing the activities will count toward your overall grade in the course, and these points can be used to replace grades on reading quizzes. If you have aced all the reading quizzes, these points can be applied toward your score on the larger assignments.
In the spirit of the class -- and to ensure that everyone has the chance to discover these holes -- please do not tell your classmates about your discovery.