I'm making two species of horse based off of the mythological horses sleipnir and helhest. My interpretations of them are probably a bit questionable in terms of their practicality, so I wanted to make sure that they were sound designs for their intended purpose, and at least able to be bent in anatomical science to some reasonable degree. Sleipnir - An eight-legged horse. Its legs are spread evenly among the side of its underbelly, effectively creating a wall of legs on each side of the body. In more detail: behind the forelegs is an identical pair of legs, and behind those, or in front of the hind legs, is another set of the same legs. The goal is increased traction and stability at the cost of speed, effectively creating a tank of a horse for a war mount (or maybe not, let me know if this is all wrong). Helhest - A three-legged horse. Its legs are arranged in a straight line through the length of the middle of its underbelly. In more detail: imagine a normally functioning leg that extends downward from the center of the horse's sternum, then two more legs of the same fashion behind it in a straight line. The goal is increased speed and turning, but decreased traction, stability, and braking. This effectively makes a motorcycle of a horse, able to turn on a dime and maintain its extreme speed (presumably, please tell me if it'll even be fast).