 Animal skin was used to make the pages in medieval manuscript books and the skin could be used from sheep, or from calves, from goats, or even from deer. This is a skin of vellum, this is calf skin and it is a byproduct of the meat and dairy industry. You can see here the shape of the vertebrae on this skin and this is where the haunches are, coming up the spine here, this is the neck. These parts of the skin are the thicker parts because this is the protection that the animal needs. Round the ribs are the thinner parts because the animal doesn't need protection. When selecting a skin for setting out a book care has to be taken to avoid the thicker parts because this will mean that if it's used for the fold the book will be continually springing open, if it's used for the edges of the pages the book won't close properly. There are two sides to the skin, the hair side and the flesh side. This is the hair side which is more marked, sometimes you can see little spattering of black spots or brown spots which are the hair follicles and it has more tooth for writing, it's got a much better surface for writing. The other side here is the flesh side and this is whiter, waxier and smoother and is more difficult to get a good tooth with a pen for writing. They weren't too careful with skins in medieval manuscripts and quite often you can see these holes here which are called lacuna or lacunae and they either made it so that these were on the edges of the pages or they simply wrote round them or in some cases they actually sewed them up.