150 PBOCBEDINGS OF THE GEOIOGICAL SOCIETY. 



Sternbergice. — The fine specimen of the axis of an erect Sigillaria 

 already referred to shows that the pith of these trees was of that 

 transversely laminated character which gives rise to the fossils 

 known as Sternheygio}. Hence we may suppose that some at least 

 of the numerous casts of Sternbergice found in the Coal-formation 

 have been derived from Sigillarice ; but this can be ascertained only 

 by a careful microscopic examination of the remains of woody mat- 

 ter clinging to the casts. The results of the study of a considerable 

 number of specimens may be stated as follows : — 



(a) As Prof. Williamson and the writer have shown, some of 

 these Stern})ergia--^it\i.^ belong to coniferous trees of the genus Da~ 

 doxylon. Plate YII. fig. 1 represents a beautifully preserved cylinder 

 of this kind enclosed in the wood of Dadoxylon materiarum. 



(6) A few specimens present multiporous tissue, of the type of 

 Dictyocoylon, which, according to Williamson, has a Sternbergia-^x\h. 

 Plate VII. fig. 4 affords an instance of this. 



(c) Other examples show a true scalariform tissue, comparable with 

 that of LejndojMoios ox Lepidodendron, but of finer texture. Corda has 

 shown that plants of the type of the former genus (his LomatopTiloios) 

 had 8ternbergia-^i^?:. Some plants of this group are by external cha- 

 racters loosely reckoned bybotanists as ribless SigiUarice(Clathixcria); 

 but I believe that they are not related even ordinally to that genus. 

 Plate VII. fig. 5 represents a Sternhergia, with tissue partly reticu- 

 lated and partly scalariform. Plate VIII. fig. 7 represents a speci- 

 men with true scalariform tissue. Plate VII. fig. 6 is a scalariform 

 vessel of Lepidophloios drawn to the same scale for comparison. It 

 wiU be seen that it is of much coarser texture. 



(d). The majority of carboniferous Sternbergice show structures 

 identical with those described above as occurring in erect Sigillarice. 

 Such Sternbergice and their structures are represented in Plate VII. 

 figs. 2 and 3, and Plate VIII. figs. 8, 9, 13. Fig. 8 is a reduced 

 section of a large flattened tree, apparently a Sigillarice with Stern- 

 hergia-])ith. (fig. 9), of great beauty, and not dissimilar from those 

 sometimes found in the erect Sigillarice. The tissue enclosing it was 

 unfortunately imperfectly preserved, but had three rows of pores 

 (fig. 9«). . _ 



Structures in Coal. — The constant association of Sigillaria with 

 ■the beds of coal, in the underclays, in the roof-shales, and in the coal 

 itself, is too well known to require any detailed reference ; and the 

 inevitable conclusion that the Sigillarice were the principal plants 

 concerned in the accumulation of the mineral fuel of the true coal- 

 measures is generally accepted by geologists. It would naturally 

 follow from this that tissues of Sigillaria should be more abundant 

 in the coal than those of other plants. Accordingly, as I have 

 shown in my paper on the " Structures in Coal," and on the 

 " Conditions of Coal-deposition," tissues similar to those above 

 described are those which actually occur most abundantly in the 

 mineral charcoal of the coal-seams. That of the liber or fibrous bark 

 is perhaps the most abundant of all, and that of the woody axis the 

 next in frequency of occurrence. 



