French binders have always preferred smooth or crushed morocco for their bindings, as it is easier to gild upon. Morocco is sensitive to damp, and if affected it quickly betrays it by giving out the strong scent of goat which is normally quite absent. Two new leathers have been recently put upon the market as rivals of morocco: one of these is seal skin and the other the skin of the sea-lion. Seal skin is finished in the same way as morocco and looks very like it, but it is, I think, not so good. It is softer, more full of oil and has a peculiar, almost fishy, smell. The softness of seal leather makes it unfit for binding books that are likely to have much hard wear, but the oiliness is probably its worst fault, as books standing next to it are apt to be stained. But it is undoubtedly a good-looking and useful leather, and if it can be put upon the market at a less cost than morocco it is sure to have a considerable vogue. Sea-lion skin is only fit for use on big books; it is very strong and is curiously ridged in large ridges. It has the same oiliness that seal has, but not in so marked a degree. There are, of course, several other leathers in which books have been bound as curiosities, and these are generally noted in some way; a book in the British Museum is lettered outside “Kangaroo,” and manuscript notes are in others telling us in what strange materials they are covered. Fish skin, known as shagreen, has sometimes been used for bindings; it is very strong but inelastic, and soon goes at the joints. In the seventeenth century it was largely imitated in calf, stamped with a grain. Perhaps the most curious leather in which any book can be bound is human skin. Such treasures are by no means unknown. It is said that a friend of Camille Flammarion the French writer, possessed beautiful shoulders, and that when she died she bequeathed her skin to him as he had always admired it. He had the skin tanned and used some of it for a binding of one of his own books, “Ciel et Terre.” There are other examples in private ownership, but so far as public libraries are concerned the only instance I know of is now in the Carnavalet Library at Paris. It is a copy of the Constitution of 1793, and is bound in the skin of one of the revolutionaries who was killed at the time. The skin was tanned at Meudon. Human skin, undyed, looks like thick calf, and it is most difficult to get entirely rid of the hair.