Scrooge doesn't believe the ghost is Marley until Marley removes a bandage. Which bandage does Marley remove?

Marley removes the bandage around his head.

At this the spirit raised a frightful cry, and shook its chain with such a dismal and appalling noise, that Scrooge held on tight to his chair, to save himself from falling in a swoon. But how much greater was his horror, when the phantom taking off the bandage round its head, as if it were too warm to wear indoors, its lower jaw dropped down upon its breast!