Palaeontologie. 473 



spermous plan, but characterised by an architectural complexity 

 far beyond that represented in the seeds of any modern Conifer 

 or Cycad. 



In such genera of Gymnosperms as Cordaites, Pitys, and 

 others, we have examples of forest trees possessing wood almost 

 identical with that of existing species of Araiicaria, but distin- 

 guished by certain pecuHarities which point to a relationship 

 with members of the Cycadofiiices, and suggesting that Conifers 

 as well as Cycads may have sprung from a filicinean stock. 



Two facts stand out prominently as the result of a general 

 survey of what are practically the oldest records* of plant-life. 

 One is the abundance of types which cannot be accommodated 

 in our existing Classification founded solely on living plants. 

 Another fact that seems to stand out clearly is the almost 

 worldwide distribution of several characteristic Lower Carbo- 

 niferous plants. 



Upper Carboniferous (Coal-Measures) and 



Permian Floras. 



From the Lower Carboniferous formation we pass on to 

 the wealth of material afforded by the Upper Carboniferous and 

 Permian rocks. The general character of the preceding Vege- 

 tation is ratained with numerous additions. Archaeocalamites 

 is replaced by a host of representatives of the genus Calamites, 

 an Equisetaceous type with stout woody stems. Side by side 

 with the Calamites there appear to have existed plants which, 

 irom their still closer agreement with Equisetiim, have been 

 described by Zeil 1er, Kidston, and others as species of 

 Eqiiisetites. The genus Sphenophylliim, a solitary type of an 

 extinct family, was represented by several forms. Lycopods, 

 with trunks as thick and tall as forest trees, were among the 

 most vigorous members of the later Palaeozioc forests. Although 

 recent research has shown that several of the supposed ferns 

 must be assigned to the Cycad-fern alliance, there can be no 

 doubt that true ferns had reached an advanced state of evolution 

 during the Permo-Carboniferous epoch. The abundance of 

 petrified stems of the genus Psaronius, of which the nearest 

 living representatives are probably to be found among the tro- 

 pica! Marattlaceae, demonstrates the existence of true ferns. 

 The most striking fact as regards the Permo-Carboniferous ferns 

 is the abundance of fertile fronds bearing sporangia which ex- 

 hibit a more or less close agreement with those of the few sur- 

 viving genera of Mavattiaceae. Others exhibit a close resem- 

 blance to those of modern Gleichenlaceae, Schizaeaceae, and 

 Osmiinclaceae. The sporangial characteristics of the different 

 families of living ferns are many of them to be found among 

 Palaeozoic types, but there is a frequent commingiing of structura! 

 features showing that the ferns had not as yet become differen- 

 tiated into so many or such distinct families as have since been 

 evolved. 



