122 ^Annual Report of the Council. 



At the time of Williamson's death, four of these memoirs 

 had been read to the Royal Society, dealing with Cata- 

 mites, Catamostachys, Sphenophytlum, Astromyeton, Kaloxylon, 

 Lyginodendron, and Heterangium ; but up to the time of 

 writing only the first two have appeared in the Transactions 

 (see Vols, for 1893, 1894). 



It is as yet, perhaps, too soon to pass a reliable and 

 final judgment upon the merits of these palasobotanical 

 memoirs, and to institute a comparison of them with the 

 publications of other authorities on Carboniferous plants. 

 At any rate, such a task will not be attempted here. 

 But, whatever be the verdict of future palseobotanists,. 

 certain conclusions have already made themselves evident, 

 which it will hardly be possible, at any time, to ignore. 



In the first place credit must be given to Williamson 

 for the fact that he was amongst the first to recognise 

 the value of thin sections of his specimens suitable for 

 the microscopical examination of their structure, and for 

 the share he had, not only in the introduction of such, 

 sections, but in developing and extending their preparation 

 on scientific lines. As a result of this, he was able to extend 

 our knowledge of the structure of carboniferous plants far 

 beyond the point at which it had been left by previous 

 workers; and whatever advances in the same direction are 

 made in the future, they are hardly likely to obscure the 

 fact that Williamson's observations lie at the foundation 

 of this branch of the subject. In the next place it will 

 always stand to his credit, that he first demonstrated, in 

 opposition to the views of some of his contemporaries 

 that the Vascular Cryptogams of the Coal Measures 

 had a mode of growth which in existing plants is almost 

 entirely restricted to Gymnosperms and Dicotyledons. 

 By means of this their stems, and sometimes other axial 

 organs, were capable of increasing in diameter by means 

 of one or more cambial layers, and so attaining to shrubby 



