102 



POSSIL PLANTS. 



My neighbour Professor Williamson has described some portions of DiploxyloTiy 

 Sigillaria, and Stigmarial which, he thinks, confirms his opinion that all these plants 

 had piths composed of parenchyma, and not piths of vascular tubes of various sizes, and 

 sometimes more or less mixed with orthosenchymatous tissue, as I had described as 

 occurring in the two first-named genera; in fact, that their piths and the pith of 

 Ijapidodendron Harconrtii were much the same in structure. 



My specimens described in the ' Quarterly Journal of the Geological Society ' and in 

 the ' Phil. Transactions ' were probably in a more perfect state than any figured and 

 described previously, so far as Diploxylon and 8'ujillana were concerned. As for 

 Stigmaria no one had described the pith except Goeppert^ and myself ; and both of the 

 specimens described by us Avere looked upon as more than doubtful by recent writers. 

 Professor Williamson says, " I have elsewhere called attention to the way in which the 

 rootlets of Stigmaria have penetrated everything within their reach that was penetrable ; 

 and I have no doubt that in both Professor Goeppert's and Mr. Binney's specimens these 

 supposed medullaiy vessels were really Stigmarian rootlets that had found their way into- 

 the interior of the cavity left by the decay of the medulla, and been mistaken for a part 

 of the plant into Avhicli they had intruded themselves." Now, in my Staffordshire 

 specimen, which exhibited all the external characters of Stigmaria ficoides, mention is 

 made only of the large vascular bundles found in the axis, without calling them medullary 

 or any other vessels. As figured in the plate and described in the letterpress no one 

 could scarcely take them for the rootlets of Stigmaria. The woody cylinder was one of 

 those having the inner parts of their circle close together, and not open, as in Professor 

 Goeppert's specimen. It is possible that the large tubes in ray specimen are not in their 

 normal condition ; and they may have been somewhat altered in the process of minerali- 

 sation ; but it is very improbable that they were ever introduced into the axis after the 

 pith had been removed. The specimen figured and described by Goeppert is very 

 different from mine, being more open in the spaces between the wedges of the woody 

 cylinder ; and its central part is enclosed in a Stigmaria, showing the exterior in a most 

 beautiful state of preservation. It appears to me that the vascular bundles in the pith, 

 though it might be urged that they have been squeezed from their true position between 

 the wedges of the inner radiating cylinder into the parts where they are now found, are 

 certainly not intruded rootlets. In comparing Geoppert's and ray speciraens with Professor 

 Williarason's any one will see that they are in a rauch raore perfect state of preservation 

 than the Oldham fragments. 



Many beautiful specimens of Stigmaria, showing structure, have been met with in the 

 trap^ash of Scotland by Mr. Greive and Mr. John Young of the Hunterian Museum, 

 Glasgow, to both of whom I am much indebted for their kindness in presenting rae with 



1 'Phil. Transactions,' 18/2 ; Part II of the Professor' Memoir "On the Organisation of the Fossil 

 Plants of the Coal-measures," p. 215. 



2 'Genres des Plantes fossiles,' pi. 13. 



