The Geographical Distribution of Animals, with a Study of the Living and Extinct Faunas, as Elucidating the Past Changes of the Earth's Surface

Abstract

II.

THE second part of his great work on Geographical Distribution Mr. Wallace devotes to the discussion of fossil animals. It might seem at first sight, as our author observes, rather out of place to begin the systematic treatment of this subject with extinct animals rather than with recent ones. But those who take the trouble to read these most interesting chapters will speedily convinced to the contrary. Imperfect as is our knowledge of the geological past, enough has been already ascertained to enable some enchanting theories to be started which account to a greater or less extent for some of the most difficult problems of the present. As regards the comparatively recent extirpation of large and important forms which has taken place in Europe, in North America, and in South America alike since Post-Pliocene times, “it is clear,” our author tells us, “that we are now in an altogether exceptional period of the earth's history,” some idea of which it is very necessary to realise. “We live in an impoverished world, from which all the hugest and fiercest and strangest forms have recently disappeared.” The cause of this great change over such a large part of the world's surface was, in Mr. Wallace's opinion, the “glacial epoch,” which, according to Mr. Belt's theory, heaped up most of the water in the earth in mountains of ice round the two poles and left the great ocean-beds comparatively dry. This, we are told, “must have acted in various ways to have produced alterations of the levels of the ocean as well as vast local flows, which would have combined with the excessive cold to destroy animal life.” We are not sure that this is a very satisfactory explanation of the simultaneous disappearance of the great Irish Elk from Europe and the Megatherium from South America, but it is at all events some explanation of an obscure point, and deserves careful consideration. So also do those few cases in which geological evidence is already sufficient to give us indications of the original birth-place of some of the mammalian types, and of the mode in which has come about their present state of distribution.

The Geographical Distribution of Animals, with a Study of the Living and Extinct Faunas, as Elucidating the Past Changes of the Earth's Surface.

By Alfred Russel Wallace. Two Vols, 8vo. (London: Macmillan and Co., 1876.)