The Outline of Science 



RECENT TIMES Human civilisation. 



PLEISTOCENE OR GLACIAL 



TI.MK Last great Ice Age. 



CENOZOIC ERA 



MIOCENE AND PLIOCENE 



TI.MKS Emergence of Man. 



EOCENE AND OLIGOCENE Rise of higher mam- , *\ 

 TIMES . mals. 



MESOZOIC ERA 



CRETACEOUS PERIOD 



JURASSIC PERIOD . . 

 TRIASSIC PERIOD 



Rise of primitive mam- 

 mals, flowering plant;, 

 and higher insi fts. 



Rise of birds and fly- 

 ing reptiles. 



Rise of dinosaur rep- 

 tiles. 



PALEOZOIC ERA 



PERMIAN PERIOD Rise of reptiles. 



CARBONIFEROUS PERIOD . Rise of insects. 

 DEVONIAN PERIOD .... First amphibians. 



SILURIAN PERIOD Land animals began. 



ORDOVICIAN PERIOD . . . First fishes. 

 CAMBRIAN PERIOD .... Peopling of the sen. 



PROTEROZOIC AOE8 Many of the Backboneless stocks began. 

 ARCHEOZOIC AQE8 Living creatures began to be upon the earth. 



FORMATIVE TIMES . 



Making of continents and ocean-basins. 

 Beginnings of atmosphere and hydrosphere. 

 Cooling of the earth. 

 Establishment of the solar system. 



In the Silurian period in which the peopling of the seas went 

 on apace, there was the first known attempt at colonising the dry 

 land. For in Silurian rocks there are fossil scorpions, and that 

 implies ability to breathe dry air by means of internal surfaces, 

 in this case known as lungbooks. It was also towards the end of 

 the Silurian, when a period of great aridity set in, that fishes ap- 

 peared related to our mud-fishes or double-breathers (Dipnoi), 

 which have lungs as well as gills. This, again, meant utilising 

 dry air, just as the present-day mud-fishes do when the water 

 disappears from the pools in hot weather. The lung-fishes or 

 mud-fishes of to-day are but three in number, one in Queensland, 

 one in South America, and one in Africa, but they are extremely 



