What sausage casing is this?
They choose edible casings, either way, you're better off taking the casing off. 

It sounds like it's a cellulose synthetic casing. It's possible to be natural casing, but papery fibrous leads me to think cellulose.  

I've included some pictures to aid you along so you can guess for yourself.  Often it's easier to tell by the extra casing at the ends since natural and synthetic bunch up differently.

Here's a picture of synthetic casing from this morning's session (it's a sopressata):

 

This is what it looks like cured and partially peeled:



And this is what natural casing looks like fresh: