THE PREPARATION OP THE EARTH FOR MAN's ABODE. 89 



■^ Fterijffohis, in the Geological Museum, Jerm>ni Street, 

 measures 4 feet in leugtli. As the beautiful Devonshire 

 marbles conspicuously show, reef-building corals worked as 

 industriously as now. In this period, too, there was a great 

 development of plant life, both aquatic and terrestrial, 

 including amongst the land plants lycopods. equisitaceae, 

 rhizocarps. and an abundance of true ferns, Filices, vascular 

 spore-beariDg plants, amongst the highest of the crypto- 

 gams. When the little likelihood of land plants being 

 included and preserved in marine deposits is borne in mind, 

 we cannot wonder that the far more ancient plants of Cam- 

 brian times (if such there were) have not yet been met Avith 

 to give us examples of the lower steps of our terrestrial flora. 



A further advance is distinctly seen when the Carboni- 

 ferous rocks are examined. Comprising, as they do in some 

 places, fully 3,000 feet thickness of limestone, Avhat a 

 wonderful amount of animal life is proclaimed ! For this 

 is a marine deposit, and so has been produced by the 

 accumulation of material secreted by animal forms as 

 •solid matter to form their endo- or exo-skeletons. Innu- 

 merable eX'Amples of the beautiful structures built up of this 

 organically converted solid matter have been perfectly 

 preserved in the crinoidal, shelly, and coralline limestones of 

 Derbyshire and other localities, which are well-known 

 objects in our museums. In Carboniferous rocks, too, there 

 is evidence of the appearance on the globe of a class of 

 vertebrates higlier than the fishes of the Devonian rocks. 

 This, the Amphibia, is represented by the order Lahipniitho- 

 dontia. The Amphibia, or Batrachia, best known now by 

 ■our frogs and toads, are intermediate between fishes and 

 reptiles. Insects of several orders seem also to have 

 •abounded. 



But it is the wonderful preservation of the produce of 

 plant-growth that gives to the Carboniferous rocks their 

 greatest interest and their chief value to man. The coai 

 ■seams in these rocks are but consolidated masses, or beds, of 

 vegetable matter grown on land or, at least, on swampy 

 areas. This enables us to ascertain the biological level to 

 which plant forms had attained in the Palaeozoic epoch. 

 It also shows that the climate then prevailing over a large 

 portion of the earth's surface was warm, or at least very 

 mild; for the vegetation in temperate regions was as profuse 

 AS it is at the present day in the forests of the Amazon and 

 ■other tropical river valleys. Nor were the Carboniferous 



