Sidehill gouger

A goat-like animal of the northern Rockies.
Sidehill gougers have long legs on one side and short legs on the other, so that they can stand upright while grazing on steep slopes. Gougers come in two varieties- clockwise gougers have longer left legs, and circle hills in the clockwise direction; counterclockwise gougers have longer right legs, and circle counterclockwise. The naturally sociable nature of the sidehill gouger is inhibited by the fact that animals of the same chirality can never see each other face to face, and animals of opposite chirality who meet and pass each other have to make a full circuit of their home mountain before they can meet again.

For obvious logistical reasons clockwise and counter-clockwise sidehill gougers are usually unable to mate. On those rare occasions when the two varieties do interbreed, the offspring often have mismatched legs- long front-right and back-left, short front-left and back-right, for instance. These unfortunates, when they first learn to walk, stumble awkwardly until they find an uneven patch of ground that fits their mismatched legs, lock-and-key-style, and stay in that spot for the rest of their short lives.

Two rarer variants exist: The uphill gouger has short front legs, and spends its life climbing upward till it reaches a mountain peak, where it dies of starvation, unable to leave. The downhill gouger has short hind legs, and slowly descends until it reaches an ocean, where it dies of thirst.

Similar creatures include the cyascutus, with its telescoping legs, the pinnacle grouse, which has only one wing and flies in circles, and the foodoo bird, which flies in ever-tightening concentric circles until it disappears up its own asshole.

The pinnacle grouse and other American mythical fauna are described in Jorge Luis Borges' Book of Imaginary Beings, though the sidehill gouger is not mentioned.