The outermost layer of the skin (as in epidermis or cuticle). An outer covering.

“It is this which, when the scarfskin and hair have been removed, is converted by the process of tanning or tawing into leather.”
From: Cooley's Practical Receipts, Volume II by Arnold Cooley

There were the folds of lips around it and cheeks, the baby hull from the throat down walled in it's scarfskin film, the cells flattened now without their water. (q. Back, by James McMichael)
Source: http://www.dictionary.com/browse/scarf-skin (derived at 29-3-2016)