The Nails

   Nails, claws and hoofs are found at the end of the digits (fingers and toes). These are all produced by the skin. A hoof surrounds the toe. A claw is sharp and grows out from the end of a toe. Nails are the flattened claws of the highest order of mammals— primates. Animals in this order include monkeys, apes, lemurs and man.
   Nails are composed of a substance called keratin, a horny material which protects and wears. They are modified reptilian scales consisting of a hard top plate, the unguis, and a softer under plate, the subunguis. The subunguis corresponds to the bottom (ventral) side of a claw. In nails, this region is much reduced.
   The crescent or whitish half-moon on the nail base, lies over an area called the matrix. Nails grow Trom the matrix, which is formed by the deepest layer of the outer epidermis, the germinative layer. Growth from the matrix is continuous unless it becomes seriously injured. The average nail grows about one-eighth of an inch a month. A fold of thin skin called cuticle surrounds the nail base.