EVOLUTION 917 



Thus all the facts of botany and zoology are "evidences of 

 evolution". 



It is useful, however, to indicate some of the sets of facts that 

 point in a peculiarly impressive way to the Evolution-idea. As these 

 have been restated many times since Darwin marshalled them in his 

 Origin of Species (1859), a summary treatment will suffice here. 



{a) Geographical. — Since it was on the voyage of the Beagle 

 that the evolutionist view of Nature was vitally borne in on Darwin's 

 mind, it is fitting to begin by referring to the geographical evidence. 

 Darwin was, he tells us, greatly impressed by the number of extinct 

 ground-sloths (Megatheriums and Glyptodonts in the order Eden- 

 tata) to be unearthed in South America, which is the modem head- 

 quarters of the sloth and ant-eater order. This correspondence 

 between the extinct and the extant in the same area is eloquent. 

 "This wonderful relationship", Darwin wrote, "in the same continent 

 between the dead and the living will, I do not doubt, hereafter throw 

 more light on the appearance of organic beings on our earth, and 

 their disappearance from it, than any other class of facts." 



On the equatorial Galapagos Islands, which Darwin visited at the 

 age of twenty-six, he found ten different kinds of giant tortoise on 

 ten adjacent islands, and five kinds in different corners of the largest 

 island, which is called Albemarle. What could it mean but that 

 isolated groups of an original stock, marooned on a volcanic peninsula 

 that became an archipelago, varied in slightly different directions 

 on the different islands, and that isolation prevented any pooling 

 of the new departures ? The same holds in regard to the land lizards 

 of the genus Tropidurus, for nearly every island has a peculiar 

 species; yet of the imique marine lizard, Amblyrhynchus cristatus, 

 that can swim, even from isle to isle, there is but one kind, though 

 there is also a non-aquatic relative called Conolophus. Can we wonder 

 that Darwin felt himself "brought near to the very act of creation" ? 



In further development of such strong geographical evidences 

 consideration should be given to the fauna of oceanic islands (see 

 Wallace's Island Life); to the widespread distribution or repre- 

 sentation of archaic t5^es, like the Lung-fishes (Dipnoi), the Lance- 

 lets (Amphioxus), the King-crab (Limulus), and the relatives of 

 Peripatus; and to detailed cases like the geographical distribution 

 of the Marsupials, which are now for the most part restricted to 

 Australia, though once with a much wider range. 



(h) Pal^ontographical. — Many great events must have oc- 

 curred in the ages now represented by Pre-Cambrian and Cambrian 

 rocks which are relatively poor in fossil remains, but admitting this 

 we cannot but be impressed with the disclosure that the rock-record 

 makes of a gradual ascent of life. In Ordovician and Silurian times 

 the only backboned animals were the fishes; ages passed and Am- 

 phibians appeared, with their first footsteps in the Devonian and 



