12 STIGMARIA FICOIDES. 



medulla and were the sources whence the vascular bundles going to the rootlets 

 were derived. This, however, is altogether a mistake. 1 



Xylograph 5. 



from the clay parting, through the upper coal, and protruding somewhat into the roof of the mine. 

 On removing this stem, the impression left by its base on the subjacent fireclay, exhibited, very 

 clearly, the crucial marking of Plate II, fig. 4. The fireclay separating the two coals was therefore 

 the soil in which this stem had commenced its growth and into which its roots had penetrated. 

 In like manner, Mr. Bradbury has obtained in the Bent Mine, a stem which was bared eighteen 

 inches below, and which not only ascended some distance into the coal but reappeared immediately 

 above it. A record kept, for but a few months, of all the cases of stems penetrating, or con- 

 tinuous through, the coal would supply a sufficient number of them to make any doubt as to the 

 possibility of such occurrences most unreasonable. At the same time it is easy to understand why 

 such should not be the ordinary positions in which such stems and roots would be preserved. 

 Xylograph 5 certainly represents an instance of a tree which began to grow when the lower coal 

 was covered by a layer of fireclay, in which latter it took root, and which continued to grow sufficiently 

 long to allow the base of its stem to be imbedded in the vegetable soil ultimately converted into the 

 upper coal. In the same way, if the stem b of Xylograph 4 really belonged to the base, a still more 

 remarkable survival of the tree-trunk must have taken place. But the length of the life of the stem 

 necessary, in all probability, for the accumulation of sufficient vegetable soil to form a thick bed of 

 coal would be so great as materially to exceed the duration of any tree — living or dead. Hence 

 it is that we so frequently find these rooted stems resting upon the coal, into which, however, their 

 Stigmarian roots freely plunged. 



Having so many proofs that some of the examples of Stigmaria? discovered in the fireclay or 

 seat-bed are the downward extensions of Sigillarian and Lepidodendroid trees, it surely can no 

 longer be doubted that the fragments of this identical Stigmaria ficoides with which that clay is so 

 constantly filled must also be portions of similar roots. Such fragments, both of roots and rootlets, 

 are extremely abundant. Indeed, it is rare to find a fireclay in which such is not the case ; but how 

 these roots have so often become disturbed and broken up is a question not easily answered. 



1 In p. 214 of my Memoir II, ' Phil. Trans.,' 1872, referring to a retrogressive tendency on the 

 part of several writers on Stigmaria, I said " the first movement in the wrong direction originated 

 with Professor Goeppert, who described a Stigmaria (' Genres des Plantes Possiles,' tab. 13) with 

 vascular bundles passing longitudinally through the pith, and from which he believed the vascular 

 bundles going to the rootlets were supplied. In this he was followed by Sir Joseph Hooker 

 (' Memoirs of the Geological Survey of Great Britain '), who clearly affirmed the existence of 

 medullary rays and bundles, but adopted Goeppert's idea as to their origin." " Mr. Binney recognised 



