are opposed in this respect to the upper, because the first joints are

opposites, the shoulder bending forwards, the hip backwards; wherefore

also the ankle bends backwards, and the wrist of the hand forwards.

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This is the way then the limbs bend, and for the reasons given.

But the hind limbs move criss-cross with the fore limbs; after the off

fore they move the near hind, then the near fore, and then the off

hind. The reason is that (a) if they moved the forelegs together and

first, the animal would be wrenched, and the progression would be a

stumbling forwards with the hind parts as it were dragged after.

Again, that would not be walking but jumping, and it is hard to make a

continuous change of place, jumping all the time. Here is evidence

of what I say; even as it is, all horses that move in this way soon

begin to refuse, for example the horses in a religious procession. For

these reasons the fore limbs and the hind limbs move in this

separate way. Again, (b) if they moved both the right legs first the

weight would be outside the supporting limbs and they would fall. If

then it is necessary to move in one or other of these ways or

criss-cross fashion, and neither of these two is satisfactory, they

must move criss-cross; for moving in the way we have said they

cannot possibly experience either of these untoward results. And

this is why horses and such-like animals stand still with their legs

put forward criss-cross, not with the right or the left put forward

together at once. In the same fashion animals with more than four legs

make their movements; if you take two consecutive pairs of legs the

hind move criss-cross with the forelegs; you can see this if you watch

them moving slowly. Even crabs move in this way, and they are

polypods. They, too, always move criss-cross in whichever direction

they are making progress. For in direction this animal has a

movement all its own; it is the only animal that moves not forwards,

but obliquely. Yet since forwards is a distinction relative to the