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Show 390 DARWINISM OIIAl'. of the lowering of the temperature in the ~leistocen? age, while their descendants have found a congemal home m the warmer reo-ions of Eastern Asia. "In th~latest stage of the Pliocene-the Upper Pliocene of the Val d'Arno-the Cervus dicranios of Nesti presents us wi th antlers much smaller than those of the Irish elk, but v ·ry complicated in their bran~hing. T~is animal surv~vcd in to the succeeding age, and 1s found m the pre-glacial forei-it bed of Norfolk, being described by Dr. Falconer under the name of Sedawick's deer. The Irish elk, moose, . tag, reindeer, and fallow deer appear in Europe in the Pleistocene age, all with highly complicated antlers in the adult, and the n.n;t possessing the largest antlers. yet .known. Of the~c th.c I n~h elk disappeared in the Prehistoric age, after havmg h vc(l 111 countless herds in Ireland, while the rest have li vccl on i 11 Lo 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 changcfi arc analoaous to those which are observed in tho developm 'nt of antle~ in the living deer, which begin with a simple point, and increase in number of tines till their limit of growth lle reached. In other words, the development of antlers indicated at successive and widely-separated pages of the gcologil'al record is the same as that observed in the history of <t ~inglc living species. It is also obvious that the progrcssiYe diminution of size and complexity in the antlers, from the present time back into the early Tertiary age, shows th;~t we are approaching the zero of antler development in the MidMiocene. No trace of any antler-bearing ruminant has lJccn met with in the lower Miocenes, either of Europe or the United States." 1 P1·ogressive Bmin-Development. The three Hlustrations 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 <lc- 1 ~Vat1t1·e, vol. xxv. p. 84. XIII TIJE GEOLOGICAL EVIDENCES OF EVOLUTIO :r 391 ----------------------------------------- ------ veloped types--exactly such a change as we may expect to find if tho evolution theory be the true one. Many other illustrations of a similar change could be given, but the animal groups in which they occur being less famj]iar, the details wonld be less interesting, and perh;tps h:trdly intelligible. There i::;, however, one very remarkable proof of (levclopmeut that must be hricAy noticed--that afforded hy the ·toady increu e in the . ize of the brain. This Jmty be best F;tated in the words of Professor Marsh:-- "The real progress of mammalian life in America, hom tho beginning of the Tertiary to the pre ent, is well illustrated by the brain-growth, in which we have the key to many other changes. The earliest known Tertiary mammals all had very small brains, and in some forms tbi. organ was proportionally less than in certain reptiles. There was a gradt~}tl .in~rease in the size of the brain during thi~:; period, and 1t IS lllteresting to fi ncl th:.tt thi growth wa. mainly con~necl to the cerebral hemispheres, or hiuher p01tion of the bram. In most groups of mammal· the bmin h<tH gradun.lly become more. convoluted, and thus increased in <ptality :::.s well as qmtnt1ty. In some also tho cerebellum and olfactory lobes, tho lower parts of the brain, have ev n diminished in size. . In th~ long struggle for existence during Tertiary time the b1g brams won, then ns now; and the incrca in o· power thus gained rendered useless many structures inherit~cl from primitive ancestor., but no longer adapted to new conditions." This remarkable proof of development in tho organ of the mental faculties, forms a fitting climax to tho vidence already adduced of the progressive evolution of the general structure of the body, as illustrated by the bony skeleton. vVe now ya s on to another cln s of fn.cts equally . uggestive of evolutiOn. The Local Relatious o.f Fossil and Living An~mals. If all exi ting anim:1l. have h en proclncccl from :1.ncestral forms--mostly extinct--nncler the bw of variation and natural selection, we may expect to find in most cases a close rela~ ion ~etwe~n ~he livin? forms of each conntry and tho. e which mha~Jited 1t 1r: ~he m~mediately precetling epoch. But if speCies have ongmated m some quite different wa.y, either by |