BIBLIOGRAPHY. 



127 



26. BiNNEY^ {8tigmarid) : — "Many years since, after an examination of a great 

 number of specimens of Stigmaria in my collection, it occurred to me that an outer 

 radiating cylinder would ultimately be discovered. In my remarks on Stigmaria^ is the 

 following passage : — ' That part of Stigmaria which intervened between the vascular axis 

 and the bark appears to have consisted of two different kinds of cellular tissue. These 

 in most cases have been unfortunately destroyed, so that we cannot positively know their 

 true nature ; but they appear to be of different characters, for there generally appears to 

 be a well-marked division. This is often shown in specimens composed of clay-ironstone 

 which have not been flattened, and the boundary-line is generally about a quarter of an 

 inch from the outside of the specimen. More probably the outer part of the zone has 

 been composed of stronger tissue than the inner one, as is the case with well-preserved 

 specimens of Lepidodendron' It is singular that Drs. Lindley and Hooker, as well as 

 such acute observers as Brongniart and Goppert, had not noticed this line of division ; 

 but this was, no doubt, owing to the imperfect specimens they had examined. After the 

 discovery of the outer radiating cylinder by Witham in Lepidodendron, and the same 

 arrangement in Sigillaria by Brongniart, it was to be expected that such outer radiating 

 cylinder would be found to occur in Stigmaria, if it were the root of Sigillaria. After an 

 inspection of a great number of specimens, the cabinet of Mr. Russell, of Chapel Hall, 

 Airdrie, has afforded me four or five distinct specimens which give clear evidence of the 

 existence of this outer radiating cylinder in Stigmaria. They are all in clay-ironstone, 

 and have not been much compressed. He has kindly allowed me to slice two of the 

 specimens, which afford decisive evidence 



of the former existence of both an inner ^• 

 and an outer radiating cylinder. The 

 space on the outside of the inner cylinder 

 does not distinctly show the bundles of 

 vessals communicating with the rootlets, 

 although there is some evidence of their 

 former existence. The bell-shaped ori- 

 fices from which the rootlets spring are 

 well displayed, and the space between 

 them is occupied by wedge-shaped masses 

 of tubes or elongated utricles arranged 

 in radiating series, and not to be distin- 

 guished in any way from those shown in 

 pi. XXXV, fig. 5. Indeed, the transverse 

 section of the specimens there figured 

 1 'Phil. Trans.,' vol. civ, 1865, p. 592. 



- 'Quarterly Journal of the Geological Society,' vol. vi, p. 20. 



3 For this and the preceding woodcut I am indebted to the Council of the Royal Society, who have 

 kindly lent me the blocks. 



Section of Stigmaria, from Airdrie. 



