LEPIDODENDRON. 



37 



§ 8. Roots {Carruthers) . — Mr. Carrutliers, in his paper on the structure and affinities 

 of Lepidodendron and Calamites, pubhshed^ in 1867 (at page 5 of the excerpt), says, 

 " Stigmarioid roots have been determined to belong to Lepidodendron, as well as to 

 Sigillaria, and their whole structure supports this determination. I have satisfied myself 

 that there is nothing that can be truly called a medullary ray in the woody cylinder of 

 Stigmaria, but into the proof of this I will not now stay to enter. The base of the trunk 

 was divided into a few principal roots, and these again divided dichotomously, but the 

 ultimate divisions were never much attenuated. Throughout their whole course, and from 

 every portion of their circumference, they gave off rootlets of considerable length, which, 

 with the exception of a slender vascular bundle, were entirely composed of delicate hexa- 

 gonal cells. They were articulated to flagon-shaped bodies, sunk in cavities, arranged in 

 a quincuncial manner over the stem. The internal structure of Stigmaria corresponds to 

 that of the trunk of a Lepidodendron. The axis was composed of fusiform barred cells, 

 and this was surrounded by a woody cylinder, which was certainly penetrated by the 

 vascular bundles that supported the rootlets. Beyond the woody cylinder came a great 

 thickness of cellular tissue, almost always destroyed, but probably agreeing in its structure 

 with the three zones of the stem." 



^ 9. Boots {Carrutliers and Binney). — As Mr. Carruthers' conclusions, which really 

 go to the extent of proving that Sigillaria and Lepidodendron are the same plant, appear 

 to be drawn mainly from my specimens of Sigillaria vascularis and Lepidodendron vasculare, 

 described in the ' Quarterly Journal of the Geological Society,' vol. xviii, pp. lOG — ll.:2, 

 pis. iv, V, and vi, for May, 1862, it is desirable carefully to consider the subject. Of 

 course the specimens had externally all the usual characters of Lepidodendron, but in the 

 internal structure No. 3 differed considerably from Nos. 1 and 2, in possessing no internal 

 radiating cylinder outside the medullary sheath, and it was, therefore, classed in the genus 

 Lepidodendron. Up to the present time no evidence has come to my knowledge to show 

 that the central axis of Stigmaria ficoides was the same as that of Lepidodendron vascidare; 

 indeed, we are really ignorant of the structure of the medulla of Stigmaria, except so far 

 as Professor Goeppert has made us acquainted with it, and as far as my own specimens 

 of Sigillaria show ; but it is no doubt the same as that of Sigillaria vascularis. This is 

 probably not sufficient to warrant us in saying more at present than that Sigillaria and 

 Lepidodendron were very much alike, and had similar habitats, and it is scarcely sufficient 

 to prove that they were one and the same plant. 



Unquestionably the medulla of the Lepidodendron Harcourtii of Witham and Lindley 

 and Hutton, as well as a much more perfect specimen of the same species in my cabinet, 

 presented to me by Mr. J. S. Dawes, and hereinafter described, is composed of cellular 

 tissue, without any vascular bundles dispersed through it ; whilst in my Sigillaria vascu- 

 laris, both in the small specimens with rhomboidal scars and the large irregularly ribbed 



^ ' In the Journal of Botany,' 8vo, London, 18G7. 



