of the Fossil Plants of the genus Sigillaria. 71 



ness of Steinliauer's view, that its appendages did in reality penetrate 

 their matrix in the same way as root fibrils. 



Having proceeded thus far with our inquiry, we may for a moment 

 stop to give a brief recapitulation of the results that have now been 

 arrived at, as to the characters of Stigmaria, and also, to consider the 

 general corollary deducible therefrom. These results are, Ist^ that Stig- 

 maria possessed a centre, in the form of a root-stock deprived of its stem ; 

 2<7, that its centre was furnished with branches, which ran out in the 

 manner of wide-spreading roots ; and, 3(/, that its branches were pro- 

 vided with appendages, which penetrated the matrix in which they are 

 imbedded in the same way as root fibrils. All these characters, there 

 can be no hesitation in saying, amount to a complete demonstration tiiat 

 jStigmaria fulfilled the purpose of a root. 



We have now to consider the plant to which this root belonged. 

 The principal vegetable fossils of the coal-measures in the shape of 

 €tems, are included in the following list: — Megaphyton, Ulodendron^ 

 Lepidodcndron, Aiiracaria (?), some other Conifers, Cauloptcris^ Anabathra, 

 a,nd Sigillaria. With one exception, the whole of these may be readily 

 disposed of. Megaphyion is too rare to have belonged to a fossil so abun- 

 dant as Stigmaria ; Caulopteris is generally admitted to belong to a dijSer- 

 ent group of plants — the Vascular Cryptogams ; Lepldodendron is without 

 the ligneous cylinder of Stigmaria ; Ulodendron is probably in the same 

 predicament ; Auracaria (?) aind the other Conifers have the walls of 

 their woody tissue furnished with discs instead of stripes, as in Stig" 

 niaria; and Anahathra, although it ofiers a considerable approximation 

 to Stigmaria in the character of its ligneous tissue, its extreme scarcity 

 places it in the same category as Mcgaphyton, Sigillaria only remains to 

 be considered, and this may be done by giving a synopsis of parallelisms 

 between it and Stigmaria in the first instance, and then to enter some- 

 what into detail respecting some other points of agreement. 

 Sigillaria Stigmaria 



is rooted in beds of the coal-forma- vegetated in beds of the £oaJ-for«- 



tion, as proved by the Dixon- mation : 



fold, Killingworth, and North 



Biddick specimens : 

 possesses enormous roots, as shewn is of enormous size : 



by the Dixon-fold fossils : 

 is one of the most abundant stems abounds in the coal-formation: 



of the coal-formation : 

 possesses a ligneous cylinder, the possesses a ligneous cylinder, the 



tissue of wiiich is marked with tissue of which is marked wit^ 



stripes, and arranged in radiating stripes, and arranged in radiating 



series : series : 



is furnished with forked root is furnished with forked branches^ 



branches, as shewn by the Dixon- 

 fold sp,ecimens. 



