increase of speed in the pursuer is followed by an increase of speed in the pursued, since

only the swiftest will now escape; every sharp-toothed squirrel opens still harder and harder nuts, and thus leaves the

alone to produce future trees.

very hardest The squirrel

survives because it can crack nuts which other squirrels must refuse; the nut survives because it can baffle the squirrel which can crack so many other nuts.

VIII.

A BIG FOSSIL BONE.

THE cliff to eastward of the village consists of soft blue lias strata, interspersed with harder layers of concreted limestone; and both deposits are worked by the quarrymen for different purposes. The soft sticky clay of the banded belts is used in making blue lias cement at the little mill beside the harbour-our one solitary manufacturing industry-while the intermediate hard layers are burnt for quicklime in the village kilns. This morning, a message from one of the navvies, who knows my taste for antiquities, brought me up here in hot haste from the breakfast table, for fear the rival collector

should be beforehand with me in securing a splendid prize. He had found, he said, a lot of 'verterberries'-that is our local word for vertebræ—and also what he took to be a flint implement. One can never trust the scientific diagnosis of a quarryman, so I was not quite sure whether he had really hit upon a big saurian in the secondary lias, or upon some mammalian remains in the quaternary gravel which caps the cliff, and which the workmen have to clear away in the course of their excavations. Fortunately for me, it turned out to be the latter: for I do not busy myself much about 'dragons,' as our navvies call the great saw-toothed saurians, but I am always interested in a stone instrument, or anything else which bears directly upon the early history of mankind. The bones proved to be three fragments of a mammoth skeleton; and close beside them in the gravel lay the sharp flint knife in situ, with which perhaps some palæolithic hunter had scraped the bones of his huge prey a hundred thou

sand years ago, when the little river still flowed at this higher level, thirty yards above the bed of its existing channel. I have pocketed the flint after a little commercial transaction with the navvy offhand : and now I am mounting guard over the mammoth bones, waiting till a relay of workmen arrives from the village below to dig them all out for me carefully as they stand.

It is common enough to hear visitors at a geological museum say to one another, 'Ah, everything used to be so much bigger in those days'-the exact period to which they thus refer being no doubt the cosmical equivalent of that familiar historical epoch, the olden time. Looking about them at the big fossils which form the most striking features of the exhibition, they picture to themselves a world where the sea swarmed with gigantic enaliosaurians and huge cetaceans, where the land was covered with deinotheria and mastodons, where all the

birds were moas, all the lizards were crocodiles, and all the snails were monstrous ammonites. Everywhere they seem to find in fossil forms a bigger animal of each kind than any now existing. They see here an enormous Irish elk, there an immense extinct sloth, yonder a vast prototype of the little modern armadillo, and somewhere else a turtle ten times as big as the greatest living member of the tortoise group. They forget that the huge saurians were secondary animals, while the deinotherium was tertiary, the mammoth quaternary, and the moa all but modern. They forget that the age of the great ammonites was almost over before the age of the great lizards set in. They forget that the glyptodon lived in South America, while the big elk lived in Ireland. By that kind of false historical perspective which throws all the distant past into a single line, they roll together millions and millions of years; and so they get a distorted geological picture, which really quite reverses the actual