[5] 



containing fossil remains of sponges, sea-weeds, star-fishes, sea-lilies, lowly 

 shell-fish, marine worms, and the first land plants. 



Silurian, consisting of slates, limestones, etc., and containing fossil 

 remains of corals, chambered spiral shell-fish, crabs, sea-worms, and 

 bony plates and scales of a low form of fish. 



Devonian, consisting of old red sandstone, shales, and coralline 

 limestone, and containing fossil land plants, fishes, belonging to shark, 

 ray, and sturgeon families, and first fossil insect. 



Carboniferous, consisting of mountain limestone, coal, sandstone, 

 ironstone, clays, etc., and containing fossil scorpions, beetles, and 

 amphibians. 



Permian, consisting of new red sandstone, marls, magnesian lime- 

 stones, etc., and containing fossils of true reptiles. 



The Secondary division is subdivided into three periods, viz. : 



Triassic, consisting of sandstone, limestone, and clays, and contain- 

 ing fossils of gigantic reptiles and first mammals (small marsupials). 



Jurassic, or Oolitic, consisting of limestones, coral rags, clays, and 

 marls, and containing fossils of bird-reptiles and several species of mar- 

 supials. 



Cretaceous, consisting of clays, sands, soft limestone, and lignites, 

 and containing fossils of new bird-reptiles. 



The Tertiary division is subdivided into four periods viz. : 



Eocene (dawn of recent life), consisting of sandstone, limestone, 

 sands, clays, marls, coral rags, and lignites, and containing fossil equine 

 forms, birds, reptiles, bats, and marsupials. 



Meiocene (less recent life), consisting of arctic coal, limestone, sands, 

 clays, and lignites, and containing fossil apes and marsupials. 



Pleiocene (more recent life), the white and red crags of Britain, 

 containing fossil apes, bears, and hyenas. 



Pleistocene (most recent life), consisting of glacial accumulations of 

 all kinds of earths, and containing fossil remains of apes and men, and 

 implements of stone, bone, and horn, and later still of remains of lake- 

 dwellings, shell-mounds, etc. 



These different layers of stratified rocks have not always kept their 

 proper positions with regard to each other in the order they were origi- 

 nally laid down ; but, owing to volcanic eruption, have frequently 

 intruded upon each other, so that, at first sight, it would sometimes 

 appear as though the regular order of deposition had not been adhered 

 to ; but that this is not so has been made apparent by careful investiga- 



