TRIASSIC ERA. 



123 



and warm-blooded races (birds and marsupials) for the first 

 time make their unmistakable appearance. Vitality, in 

 obedience to some great law of progress, is ever pressing 

 forward to higher and higher forms, even though restricted 

 to unstable seas, and subjected to the stunting influences of 

 riverless plains and thirsty uplands. 



Of the marine flora of the trias we know little or nothing. 

 Fucus-\\ke impressions are occasionally retained on the sand- 

 stones, but so fragmentary and obscure that a " general re- 



1, Walchia ; 2. Pterozamites or Ptercphyllum from North America (Smmous). 



semblance" is all the paleontologist can affirm. When we 

 turn to the land -plants, equisetums, calamites, ferns, cy- 

 cads, and conifers are the predominating forms ; the equi- 

 setum and calaniite pointing to the marshy pools of the 

 summer-dried river-course, the fern and cycad to the scrubby 

 plain, and the coniferous trees to the open upland. The 

 triassic equisetums, calamites, and tree-ferns (sphenopteris, 



