The dancing, waltzing, or circus course movement, as it is variously known, varies in form from moment to moment. Now an individual moves its head rapidly from side to side, perhaps backing a little at the same time, now it spins around like a top with such speed that head and tail are almost indistinguishable, now it runs in circles of from 5 cm. to 30 cm. in diameter. If there are any objects in the cage about or through which it may run, they are sure to direct the expression of activity. A tunnel or a hole in a box calls forth endless repetitions of the act of passing through. When two individuals are in the same cage, they frequently dance together, sometimes moving in the same direction, sometimes in opposite directions. Often, as one spins rapidly about a vertical axis, the other runs around the first in small circles; or again, both may run in a small circle in the same direction, so that their bodies form a living ring, which, because of the rapidity of their movements, appears perfectly continuous. The three most clearly distinguishable forms of dance are (1) movement in circles with all the feet close together under the body, (2) movement in circles, which vary in diameter from 5 cm. to 30 cm., with the feet spread widely, and (3) movement now to the right, now to the left, in figure eights ([Symbol: figure eight]). For convenience of reference these types of dance may be called _whirling, circling_, and the _figure eight dance_. Zoth, in an excellent account of the behavior of the dancer (31 p. 156), describes "manège movements," "solo dances," and "centre dances." Of these the first is whirling, the second one form of circling, and the third the dancing of two individuals together in the manner described above.