[Illustration: FIG. 133.--THE GALLOP: THIRD PERIOD.] [Illustration: FIG. 134.--THE GALLOP: TIME OF SUSPENSION.] If we examine the notation of the pace of walking (Fig. 128), we see that the right fore-foot commences its pressure when the right hind-foot is in the middle of its own, and that the hinder left begins in the middle of that of the right fore-foot, and that it is itself at the midst of its pressure when the left fore-foot touches the ground, etc. In a word, the foot-fallings occur in the following order and at regular intervals--the fore right foot is here considered as acting first: right fore, left hind, left fore, right hind, and so on in succession. [Illustration: FIG. 135.--NOTATION OF THE GALLOP DIVIDED INTO THREE PERIODS OF TIME (AFTER PROFESSOR MAREY). 1, First period; 2, second period; 3, third period.] As to the nature of the bipeds which succeed one another, it is easy to understand them by means of the notation. In reading this from left to right, we see that the associations of pressure are first made by the two right feet, then by a right foot and a left one, then by two left feet, and, finally, by a left and right. It is, accordingly, a succession this time of lateral and diagonal pressures. [Illustration: FIG. 136.--NOTATION OF THE GALLOP OF FOUR PERIODS IN THE HORSE (AFTER PROFESSOR MAREY). 1, First period; 2, second period; 3, third period; 4, fourth period.] Thus, we find at the start a right lateral pressure (Fig. 129), next a right diagonal (Fig. 130), then a left lateral; finally, a left diagonal pressure. It is thus that the initial letters L, D, L´, D´ further indicate the notations represented in Fig. 128. =The Gallop.=--The ordinary gallop is a pace of three phases. The first is characterized by the fact that one hind-limb alone rests on the ground (Fig. 131); in the second the animal is on a diagonal support (Fig. 132); in the third it comes down on a fore-limb (Fig. 133). The body is then raised (Fig. 134), and to this period of suspension succeed anew the three modes of pressure indicated above. The gallop is said to be from either right or left. In the gallop from the right, the right fore-leg is the more frequently in advance of its neighbour; it is the last to be placed on the ground. The left foot of the posterior biped is the one which commences the action. An entirely opposite arrangement characterizes the gallop from the left. [Illustration: FIG. 137.--LEAP OF THE HARE (AFTER G. COLIN).]