378 THE POPULAR SCIENCE MONTHLY, 



rope point directly to migrations from Africa. Other similar exam- 

 ples are numerous. The fossil plants of the Arctic region prove the 

 existence of a climate there far milder than at present, and recent 

 researches at least render more probable the suggestion, made long 

 ago by Buffon, in his " Epochs of Nature," that life began in the polar 

 regions, and by successive migrations from them the continents were 

 peopled. 



The great services which comparative anatomy rendered to paleon- 

 tology at the hands of Cuvier, Agassiz, Owen, and others have been 

 amply repaid. The solution of some of the most difficult problems 

 in anatomy has received scarcely less aid from the extinct forms 

 discovered than from embryology ; and the two lines of research 

 supplement each other. Our present knowledge of the vertebrate 

 skull, the limb-arches, and the limbs, has been much enlarged by 

 researches in paleontology. On the other hand, the recent labors of 

 Gegenbaur, Huxley, Parker, Balfour, and Thacher will make clear 

 many obscure points in ancient life. 



One of the important results of recent paleontological research is 

 the law of brain-growth, found to exist among extinct mammals, 

 and to some extent in other vertebrates. • According to this law, as 

 I have briefly stated it elsewhere, " all Tertiary mammals had small 

 brains. There was, also, a gradual increase in the size of the brain 

 during this period. This increase was confined mainly to the cerebral 

 hemispheres, or higher portions of the brain. In some groups, the 

 convolutions of the brain have gradually become more complicated. 

 In some, the cerebellum and the olfactory lobes have even diminished 

 in size." More recent researches render it probable that the same gen- 

 eral law of brain-growth holds good for birds and reptiles from the 

 Mesozoic to the present time. The Cretaceous birds, that have been 

 investigated with reference to this point, had brains only about one 

 third as large in proportion as those nearest allied among living 

 species. The Dinosaurs from our Western Jurassic follow the same 

 law, and had brain-cavities vastly smaller than any existing reptiles. 

 Many other facts point in the same direction, and indicate that the 

 general law will hold good for all extinct vertebrates. 



Paleontology has rendered great service to the more recent science 

 of archaeology. At the beginning of the present period, a reexamina- 

 tion of the evidence in regard to the antiquity of the human race was 

 going on, and important results were soon attained. Evidence in 

 favor of the presence of man on the earth at a period far earlier than 

 the accepted chronology of six thousand years would imply, had been 

 gradually accumulating, but had been rejected from time to time by 

 the highest authorities. In 1823, Cuvier, Brongniart, and Buckland, 

 and later, Lyell, refused to admit that human relics, and the bones of 

 extinct animals found with them, were of the same geological age, 



