TIIK i AIM10NIFKKOI 



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mark ol t In- swamp, and uniting in a dome-shaped manner to support 

 the trunk. 



<. Pteridosperms and Primofllices. Fern-like fronds are 

 abundant in the Coal-measures, and the roofs of coal-seams are 

 .-oiiK'tiincs covered with beautiful impressions of such fronds. 

 I'n til recently these were regarded as true ferns, but it has been 



Fig. 97. LEP1DODENDRON ELEOANS (BROUr.Il). 



1. A terminal branch. _'. Leaf-scars from the stem. 



found that many of them belong to plants which developed true 

 seeds and not spores like those of existing ferns. They are now 

 regarded as a distinct group of plants, intermediate between ferns 

 and Gymnosperms, and are known as Pteridosperms. 



True ferns of an ancient type (Primofilices) are also represented 

 among these leaves, for some have been found bearing sporangia, 

 and stt-ms witli leaf-scars like those of modern tree-ferns also occur 

 (Psaronius). Fructiferous fronds, however, are rare, and it is 



U 



