Ql/Arrg>v*BY 



S Y S T £ M S 



I 



CARBONIFEROUS ij- 



-_-Z-Z SILURIAN z---- 





7 / '/ / //- / / / -/-/-/'/' / - / y;- 



./ 



/'•// 



ORDOV IC I /> N 



K'tifflf/ifi 



'■/■,. ';'■/. 



>.&/.&/■%<■/&■ 



TYPICAL FORMS 



LAST TRiLOBITES 



SCORPIONS 



£ 



■J 



VI 



u 



I- 

 < 



FIRST FISHES 

 MARINE SCOPPIONS 



FIRST TRILOBITES 



Fig. 4.— Plan of Geological Strata. (From Lankester.) 



