Page:Darwinism by Alfred Wallace 1889.djvu/414

 of the lowering of the temperature in the Pleistocene age, while their descendants have found a congenial home in the warmer regions of Eastern Asia.

"In the latest stage of the Pliocene—the Upper Pliocene of the Val d'Arno—the Cervus dicranios of Nesti presents us with antlers much smaller than those of the Irish elk, but very complicated in their branching. This animal survived into the succeeding age, and is found in the pre-glacial forest bed of Norfolk, being described by Dr. Falconer under the name of Sedgwick's deer. The Irish elk, moose, stag, reindeer, and fallow deer appear in Europe in the Pleistocene age, all with highly complicated antlers in the adult, and the first possessing the largest antlers yet known. Of these the Irish elk disappeared in the Prehistoric age, after having lived in countless herds in Ireland, while the rest have lived on into our own times in Euro-Asia, and, with the exception of the last, also in North America.

"From this survey it is obvious that the cervine antlers have increased in size and complexity from the Mid-Miocene to the Pleistocene age, and that their successive changes are analogous to those which are observed in the development of antlers in the living deer, which begin with a simple point, and increase in number of tines till their limit of growth be reached. In other words, the development of antlers indicated at successive and widely-separated pages of the geological record is the same as that observed in the history of a single living species. It is also obvious that the progressive diminution of size and complexity in the antlers, from the present time back into the early Tertiary age, shows that we are approaching the zero of antler development in the Mid-Miocene. No trace of any antler-bearing ruminant has been met with in the lower Miocenes, either of Europe or the United States."

The three illustrations now given sufficiently prove that, whenever the geological record approaches to completeness, we have evidence of the progressive change of species in definite directions, and from less developed to more