Vellum

Animal skin used as a writing material

Vellum is prepared animal skin or membrane, typically used as writing material. It is often distinguished from parchment, either by being made from calfskin, rather than the skin of other animals, or simply by being of a higher quality. Vellum is prepared for writing and printing on single pages, scrolls, and codices.

From Wikipedia, under CC BY-SA. More on occurri.