Fig. 5. (A) Larval lamprey (length=122 mm) with EMG recording electrodes at 20% BL (1,2), 40% BL (3) and 60% BL (4). (B,C) Muscle activity recorded during (B) moderately slow swimming (T=436±42 ms) and (C) faster swimming (T=225±13 ms). Note that the `chart speed' was adjusted so that the cycle times of the two episodes would appear similar in the figure (see time scale below). (B) During slow swimming, the mean burst proportions (BP1, BP2, BP3, BP4) were 0.23, 0.31, 0.39 and 0.31, and mean phase lags (23, 34) were 0.0086 and 0.0047, respectively. (C) During the faster swimming episode, in which the cycle times were approximately 200 ms shorter than in B, the mean values for these parameters were (BP1, BP2, BP3, BP4) 0.28, 0.37, 0.42 and 0.45, and (23, 34) 0.0066 and 0.0063, respectively. Time scale, 500 ms (A); 250 ms (B).