﻿2 Weiss and Lomax, Lepidodmdron selaginoides. 



bark, others with rhomboidal markings have the same 

 internal structure, so that the ribbed condition must be 

 looked upon as an older semi-decorticated stem from 

 which the leaf cushions have disappeared. Not only did 

 Binney find these two conditions of the stem constantly 

 associated together, but he could trace them " gradually 

 passing from one into the other."* " These facts," he says, 

 " when taken in connection with the similarity in structure 

 in the central axis, the internal radiating cylinder, the 

 space filled with lax cellular tissue between the latter and 

 the outer radiating cylinder diverging from circular 

 openings, clearly prove that the smaller specimen \Lepido- 

 dendron selaginoides\ is but the branch of the older stem " 

 [Sigillarza vascularis]. 



Williamson ('78 and '81) in parts IX. and XI. of his 

 " Organization of the Fossil Plants of the Coal Measures," 

 supports Binney's contention and this view of the identity 

 of the two forms is accepted after critical examination by 

 Solms-Laubach ('87) and by Hovelacque ('92) in his most 

 detailed and careful examination of this plant. 



There seems, therefore, to have been a very consider- 

 able amount of agreement as to the identity of these 

 plants, based upon a comparison of their internal and 

 external structure, but as far as we know, no evidence 

 of actual continuity was brought forward. It is true 

 Binney speaks of a gradual passing of large ribbed 

 specimens into smaller ones with rhomboidal scars ; but 

 from the context of the passage we gather that he meant 

 that all intermediate stages were to be found between the 

 two forms. 



In the specimen before us now, however, we have such 

 actual continuity of structure. For it represents a piece 

 of a large ribbed stem, about 6yi inches in height, which 



* See Binney, ('65), p. 490. 



