38 



FOSSIL PLANTS. 



and furrowed examples, as well as in my Lepidodendron vascidare, the medulla contains 

 numerous scalariform tubes or utricles, called by Mr. Carruthers " fusiform barred cells." 

 Li addition, we must not forget that in Lepidodendron Hm'courtii we find no trace of the 

 internal radiating cylinder so characteristic of Sigillaria vascularis, although in both plants, 

 as well as in Lepidodendron vasculare, there is evidence of an outer radiating cylinder 

 composed of fusiform utricles. This external cylinder has been shown by me to occur in 

 Stigmaria} 



In the present Monograph there will be described and figured two cones showing the 

 internal composition of their columns ; one of these exactly resembles in its structure 

 that of Lepidodendron Harcourtii, and the other is similar to that of Lepidodendron vascu- 

 lare ; so for the present, probably, it will be desirable to keep the two genera distinct. 



So far as my observations extend, plenty of both large and small specimens of Lepido- 

 dendron having rhomboidal scars are met with, whilst few ribbed and furrowed Sigillarice 

 of a small size are found, these fluted Sigillarice being for the most part large specimens. 

 In my memoir last quoted it was shown that, while the large stem of Sigillaria had small 

 branches rhomboidally scarred and of a lepidodendroid character, the large stems, having 

 the same internal structure as the branches, resembled the ordinary Sigillaria in its 

 external appearance. 



Hence, although Lepidodendron and Sigillaria are, no doubt, nearly allied, it appears to 

 me desirable to retain them as distinct genera for the present, until more evidence of 

 their perfect identity is furnished than my specimens figured and described in the 

 ' Quarterly Geological Journal ' and the ' Philosophical Transactions ' have afi'orded. 



Lepidostrobus. 



§ 10. {Lindley and others). — Prom the earliest time that Carboniferous fossil Plants 

 have been figured and described, the Lepidostrobus has appeared amongst them. Messrs. 

 Lindley and Hutton, in their ' Possil Flora,' give numerous figures of beautiful specimens, 

 as also does M. Brongniart in his ' Histoire des Vegeteaux fossiles ; ' but none of these 

 appeared to show any internal structure, owing to their being simply casts, or carbonaceous 

 impressions, in clay-ironstone or shale. 



§ 11. {Br 01011). — Dr. Robert Brown read before the Linnean Society in 1847 a description 

 of a cone {Triplosporites) which first showed the true structure of Lepidostrobus, so far, at 

 least, as the upper part of the cone was concerned, but his paper was not published till 

 1851. In the mean time, namely in 1848, Dr. Hooker published his valuable researches 

 on the structure of Lepidostrobus, showing the true nature of the cone, from a number of 

 1 'Philosophical Transactions,' vol. civ (1865), p. 593. 



