CHAPTER IV
THE RIDGES AND THEIR USES
THE palmar surface of the hands and the soles of the feet, both in men and monkeys, are covered with minute ridges that bear a superficial resemblance to those made on sand by wind or flowing water. They form systems which run in bold sweeps, though the courses of the individual ridges are less regular. Each ridge (Plate 3, Fig. 5) is characterised by numerous minute peculiarities, called Minutiae in this book, here dividing into two, and there uniting with another (a, b), or it may divide and almost immediately reunite, enclosing a small circular or elliptical space (c) ; at other times its beginning or end is markedly independent (d, e) ; lastly, the ridge may be so short as to form a small island (f ).
Whenever an interspace is left between the boundaries of different systems of ridges, it is filled by a small system of its own, which will have some characteristic shape, and be called a pattern in this book.
There are three particularly well-marked systems of ridges in the palm of the hand marked in Plate 3, Fig 6, 1, as Th, AB, and BC. The system Th is
