THE EVOLUTION OF THE PLANT-WORLD 19 



their development in Southern India, the whole vast 

 continent which they indicate being known as Gond- 

 wana-land. Their flora is marked by the absence of 

 Catamites, and, in India, of Sigillaria and Lepidodendron, 

 the former being apparently replaced by Phyllotheca 

 and Schizoneura, a distinct type of Equisetales; and the 

 presence of Sphenopteris and Pecopteris, probably Ptevi- 

 dosperms, the more obviously cycadean Pterophyllum, 

 and, above all, the abundant Glossopteris and Gan- 

 gamoptevis. Glossopteris, which has given its name to 

 this entire flora, has a rhizome described under the name 

 Vertebraria, bearing long, lanceolate or spathulate 

 foliage-leaves with a midrib and anastomosing lateral 

 veins, and smaller scale-leaves associated with sporangia 

 and possibly sporophylls. Gangamopteris seems to differ 

 mainly in the absence of the midrib. The sporangia 

 may prove to be the microsporangia or pollen-sacs of 

 a cycadeous plant, and these two abundant genera may 

 thus prove to belong either to that characteristically 

 Mesozoic class the Cycadece, or to its forerunner, the 

 Pteridospermece . 



While there is no clear evidence of true Cycads or 

 members of our existing families of Conifers in Car- 

 boniferous rocks, a change in the general character of 

 the vegetation seems thus to have begun in this southern 

 continent earlier than in the north, and to have extended 

 northward into China and Perm. The main divisions 

 of the Cryptogamia and Gymnospermia seem to entirely 

 antedate our existing system of continents. 



In Secondary or Mesozoic rocks Club-mosses, Horse- 

 tails and Marattiaceous ferns play quite a subordi- 

 nate part. The Osmundacea and forms related to 

 Gleichenia and to the Malayan Matonia and Dipteris 

 become prominent; but not the Polypodiacea. Baiera, 

 and Gink go itself, represented, from Triassic times, over 

 almost the whole globe, the Maidenhair-tree now so 

 restricted in area. True Conifers, especially forms 

 related to the broad-leaved Araitcariece and Agathis, 

 now entirely southern, become abundant. One plant 

 in every three during Jurassic times seems, however, 

 to have been a Cycad. The Cycadophyta, now repre- 

 sented by one family, the Cycadacece, comprising only 

 nine genera and about 100 species, all southern, were 

 then a varied and dominant group, almost as much so, 



