PERMIAN PERIOD 69 



cycad-conifers ; and finally shrubs and trees comparable 

 with cycads and conifers of our own time. 



Invertebrate life at the close of the Cambrian was certainly 

 well represented in its existing main divisions ; and during 

 succeeding Periods of the Age great developments went on 

 within its varied ranks. 



There were also some notable examples of what seems to 

 be the fate of all forms of life on earth. Cystids and Mastoids 

 rose, declined, and became extinct. Lampshells reached a 

 grand zenith, and then entered on a downward path. Trilo- 

 bites, after attaining vast variety of form and world-wide 

 distribution, slowly declined, and utterly passed away. And 

 sea-scorpions experienced, on a smaller stage, a like cycle of 

 fortune. 



From invertebrate ranks fishes gradually emerged, and, 

 after a rigorous Natural Selection, some forms with greatly 

 improved swimming powers, and with stronger internal 

 framework, came into evidence. In course of time amphibians 

 — evolved from certain of the fishes — made their appearance, 

 and branched out into several types. And finally from 

 amphibian ranks reptiles came forth, and took up the 

 leadership. 



In spite, therefore, of retrogressions and destructions, of 

 waste and suffering, the main movement in Life was dis- 

 tinctly onward. Nor were signs wanting at the close of the 

 Permian of coming great developments. 



