She's Got Legs -or Does She?

A few days ago, redditor jr0d7771 posted this picture and gave us a conundrum. There are obviously five young women sitting on the couch. But there are four pairs of legs. The woman in the middle appears to have none. Can you figure it out?

First off, you shouldn't be led by my assumption that it's the middle woman who has no legs. It could be any of them. When you've given up, you can read about the investigation and conclusion at The Concourse.