cestor at the opening of the Cainozoic period was a running ape, living chiefly on the ground, hiding among rocks rather than trees. It could still climb trees well and hold things between its great toe and its second toe (as the Japanese can to this day), but it was already coming down to the ground again from a still remoter, a Mesozoic arboreal ancestry. It is quite understandable that such a creature would very rarely die in water in such circumstances as to leave bones to become fossilized.
It must always be borne in mind that among its many other imperfections the Geological Record necessarily contains abundant traces only of water or marsh creatures or of creatures easily and frequently drowned. The same reasons that make any traces of the ancestors of the mammals rare and relatively unprocurable in the Mesozoic rocks, probably make the traces of possible human ancestors rare and relatively unprocurable in the Cainozoic rocks. Such knowledge as we have of the earliest men, for example, is almost entirely got from a few caves, into which they went and in which they left their traces. Until the hard Pleistocene times they lived and died in the open, and their bodies were consumed or decayed altogether.
But it is well to bear in mind also that the Record of the Rocks has still to be thoroughly examined. It has been studied only for a few generations, and by only a few men in each generation. Most men have been too busy making war, making profits out of their neighbours, toiling at work that machinery could do for them in a tenth of the time, or simply playing about, to give any attention to these more interesting things. There may be, there probably are, thousands of deposits still untouched containing countless fragments and vestiges of man and his progenitors. In Asia particularly, in India or the East Indies, there may be hidden the most illuminating clues. What we know to-day of early men is the merest scrap of what will presently be known.
The apes and monkeys already appear to have been differentiated at the beginning of the Cainozoic Age, and there are a number of Oligocene and Miocene apes whose relations to one another and to the human line have still to be made out. Among these we may mention Dryopithecus of the Miocene Age, with a very