Waving movements of the tails and contractions of both the dorsal blood vessel and intestine were observed in an anomalously double-tailed worm of the species Branchiura sowerbyi Beddard. The two tails of the worm waved asynchronously, indicating that the waving movements originated and were regulated within the tails proper. Both contraction waves of the dorsal blood vessel and of the intestine started from their tail ends and ascended the body stem a long distance, but descended the opposite tail via the forked segment only a short distance. It is likely that there exists a polarity in the propagation of contraction in these organs. Defecation movements of the intestines in the respective tails occurred independently. This implies that such movements are locally controlled within the tail region.