FERNS, FERN ALLIES, AND FOSSILS. 285 



is fairly distinct. The Cai^boniferous was certainly the 

 age of Lycopodiaceae. Lepidodendron and Sigillaria were 

 enormous in size as compared with our own Clubmosses, 

 but the similarity in habit is unmistakable. Apparently 

 also fungi attacked their trunks, and bacteria dis- 

 organised the cellulose remains. 



For the Perviian, the Tree-ferns and gigantic Cala- 

 mariae (an extinct famil}^ of Equisetaceae) may be 

 considered as the most characteristic and important 

 kinds of plants. 



In the Triassic period, the Horsetails, or Equisetaceae, 

 seem to have been relatively more important than they 

 have ever been since ; but in Triassic and Jurassic times, 

 Cycads were the dominant vegetation in almost every 

 part of the earth where fossils of these periods have 

 been discovered. The Araucaria, or Monkey-puzzle- 

 tree, and the Maidenhair- tree {Ginkgo or Salisburia) 

 seem also to have been abundant and are very widely 

 distributed in Jurassic strata. Thus after the Horsetails 

 obtained a very prominent position, they were set aside 

 for other plants belonging to a more advanced family, 

 the Gyrnnosperins. Although these pioneers of the 

 Gymnosperms, the C3^cads, the Araucaria, and the 

 Ginkgo are true flowering plants, yet they are on the 

 very border of the family, and the least specialised as 

 rea"ards their flowers and anatomical structure. Never- 

 theless they still exist, and the Cycadaceae contain some 

 7 5 species, and are widely spread in all tropical countries. 

 The Monkey Puzzle {Araucaria) is still able to produce 

 forests ; though this is only possible in the Chilian Andes 

 which is a very out-of-the-way part of the world. Ginkgo 

 seems to be almost unknown in a wild state, but it has 

 been preserved by the priests of certain Chinese temples. 



A sudden and extraordinary change occurs at the 



