Anal spur

Anal spurs are the vestigial remnants of legs found on each side of the vent in primitive snakes, such as boas and pythons. The bone is considered a hip bone, which has no connection with the spine and simply "floats" in the muscle mass. There is sometimes a bone, considered a femur, which sticks out of the snake's side. This primitive femur is then covered by a corneal spur, which resembles a claw. Males' spurs are generally longer and more pointed than females', and are used for clasping and tickling during courtship and mating. Sometimes they are used during fights to scratch the opponent.

de: Aftersporn