14 



marsupials from Australian caves are strikingly like the 

 living marsupials. In South. America there is " a won- 

 derful relationship between the dead and the living." 

 Similar relationships hold between extinct and extant land- 

 shells of Madeira and water-sheUs of the Casjiian Sea. 



Further, extinct and even living types have often affi- 

 nities with very different kinds of animals. Of living 

 animals, the lepidosiren associates in itself many character- 

 istics of different kinds of fishes. How much more is this 

 the case among fossil forms, where, as in the archeopteryx 

 and campsognathus, the hiatus between bird and reptile is 

 bridged over, so that naturalists are now obliged to classify 

 birds and reptiles together as sauropsida. 



"The zeuglodon and squalodon," again, says Huxley, 

 " constitute connecting links " between other mammals and 

 "the aquatic carnivora." Not merely are the affinities of 

 extinct with living species remarkable, but their mutual 

 affinities are equally striking, inexplicable indeed except 

 on the theory of descent. Again, we find in the geological 

 record that the forms of life change simultaneously all over 

 the world, which can only be explained by the wide and 

 speedy spreading of successful and selected modifications. 

 Again, species once lost do not reappear : this is of itself 

 a fact full of significance, but is of vast importance when 

 considered in relation to the gi'adual elaboration of struc- 

 tural organization, as revealed by the geologist's hammer. 

 The lower the rock, the lower and simpler is the species. 

 With every succeeding stratum, the volume of evidence is 

 increased by the presence of intermediate links which bridge 

 the wider differences between living forms. From the 

 simple to the complex is the law of palseoutology no less 

 than of embryology. It is indeed astounding that a record 

 so necessarily imperfect as that of a few rocks still existing 

 out of many that have been denuded and lost, bearing a 

 few accidental remains, and only very partially explored, 

 should nevertheless testify so strongly to the truth of 

 organic evolution. 



The Evidence from Geographical Distribution. — The distri- 

 bution of animals and plants cannot be accounted for by 

 differences of climate. The old and new worlds offer a 

 thousand parallels of climate, but how dissimilar are their 

 flora and fauna! You wiU remember that I drew your 

 attention to the correspondence between extinct and existing 

 forms in the same geological area. Now, not only the 



