44 THE GEOLOGICAL HISTORY OF PLANTS. 



of a laminated resinous substance found associated with the plant 

 shows that it is wholly amorphous, and, as indicated by distinct lines 

 of flow, that it must have been in a plastic state at a former period. 

 The only evidence of structure was found in certain well-defined 

 mycelia, which may have been derived from associated vegetable 

 matter upon which they were growing, and over which the plastic 

 matrix flowed." 



1 have only to add to this description that when we consider that 

 Nematophyton Logani was a large tree, sometimes attaining a diam- 

 eter of more than two feet, and a stature of at least twenty before 

 branching ; that it had great roots, and gave off large branches ; that 

 it was an aerial plant, probably flourishing in the same swampy flats 

 with Psilophyton, Arthrostigma, and Leptophleum ; that the peculiar 

 bodies known as Pachytheca were not unlikely its fruit — we have 

 evidence that there were, in the early Palaeozoic period, plants 

 scarcely dreamt of by modern botany. Only when the appendages 

 of these plants are more fully known can we hope to understand 

 them. In the mean time, I may state that there were probably differ- 

 ent species of these trees, indicated more particularly by the stems I 

 have described as Nematoxylon and Celluloxylon* There were, I 

 think, some indications that the plants described by Carruthers as 

 Berwynia, may also be found to have been generically the same. 

 The resinous matter mentioned by Prof. Penhallow is found in great 

 abundance in the beds containing Nematophyton, and must, I think, 

 have been an exudation from its bark. 



* " Journal Geol. Society of London," 1863, 1881. 



