GENERALITIES OF THE GAITS. 475 



dejuger). Lastly, when the hind are in front of the fore (a gait they 

 style unduly lengthened,), the animal is said to " overcheek," to u over- 

 cover" his steps (se mecouvrir, se mejuger). 



They say also that the horse trails himself (se piste), when one of 

 the posterior bipeds marks its imprint upon the same transverse line 

 as the anterior foot which is diagonally opposite to it; again, the im- 

 print of the posterior foot in question may be made in front or~behind 

 that of the diagonal anterior foot, and then the horse mistrails himself 

 (se depiste). These terms are only used for the gallop. 



Since the time of Solleysel l there have been distinguished in the 

 evolution of a member two principal phases or periods, the contact 

 with the ground and the elevation, during which this member supports 

 a part of the weight of the body or, on the contrary, is completely 

 lifted from the ground. We have seen (page 195) that as soon as a 

 member has passed successively through the two phases, the body has 

 passed over a distance designated under the name of complete step. 

 The two bipeds (anterior and posterior) are, in fact, conjointly con- 

 cerned in its execution ; and, even as an anterior member, for example, 

 is incapable of taking two steps in succession without the intervention 



FIG. 171. Scheme of the movement of a member during the phases of contact and elevation. 



of its congener ; even so, also, the anterior biped is unable to carry 

 itself a certain distance in advance of its primitive position unless the 

 posterior biped accomplishes exactly the same movement. 2 



On the other hand, it is known that during the evolution of any 

 member (Fig. 171), the centre of movement, H, of this member, and, 

 in consequence, the centre of gravity, progresses from H to H", 



i De Solleysel, Parfait mareschal, <5d. de 1693, 2e partie, p. 66. 



3 C. Bourgelat, Traitc 1 de la conformation exterieure du cheval, p. 245. 



