PLANTS. 9 



Sub-class SiGiLLARALES, King. 



Diagnosis. — Arborescent plants, having stems with a large pith encircled by a 

 narrow striato-tubular (ligneous ? ) cylinder, the tissue of which is intersected by 

 medullary rays, and arranged in radiating series. On the inner side of the cylinder is a 

 (reticulated ? ) medullary sheath, consisting of irregularly-arranged vessels. On the 

 outside of the cylinder is a broad zone of cellular tissue, inclosed in a distinct cuticle. 

 Bundles of spiral or striated vessels pass off from the medullary sheath, through the 

 (ligneous ? ) cylinder, into the leaves, the collective scars of which (in the typical 

 genus) are arranged in single rows on ribs, running longitudinally up the stem.^ 



The writer has not yet seen any reason for modifying the view which is advanced 

 in his " Contributions'' respecting the affinities of Sigillaria ; he is therefore led to 

 place the present group between " the highest vascular Cryptogams and the Cycadeous 

 Gymnosperms."^ 



Order Sigillariace^ {Sigillariece), Corda. 



Genus Sigillaria, Ad. Brongniart. 



Diagnosis. — " Stem conical, deeply furrowed, not jointed ; scars placed between 

 the furrows in rows, not arranged in a distinctly spiral manner, smooth, much narrower 

 than the intervals that separate them."^ 



Sigillarias have been trees, with a simple or branched stem, varying from twelve 

 to a hundred feet in height, having large, wide-spreading, thickly-fibrilled roots (most 

 probably Stigmarid), and apparently crowned with a pendant fern-like fohage ( ? certain 

 species of Neuropteris).* 



^ Vide Ad. Brongniart's "Observations sur la Structure interieure du Sigillaria elegans," &c. in the 

 'Archives du Museum d'Histoire naturelle,' tome i ; and the writer's " Contributions towards establishing the 

 General Character of the Fossil Plants of the genus Sigillaria," in the ' Edinburgh Philosophical Journal,' 

 vols, xxxvi, xxxvii, and xxxviii. 



2 Edin. Phil. Journal, vol. xxxviii. 



3 Fossil Flora, vol. i. 



"* This is the view which the writer published in the 'Edinburgh Philosophical Journal,' in 1S45. 

 Respecting the much-debated point connected with the root, he read at a meeting of the Natural History 

 Society of Northumberland, Durham, and Newcastle-on-Tyne, in May 1842, a paper, one of the principal 

 objects of which was to prove that " Stigmaria, which has hitherto been considered a distinct plant, is 

 nothing moVe than the root of Sigillaria." (Vide Literary Gazette, June 18, 1842, p. 425.) Subsequently, 

 and it is believed at the Cork meeting of the British Association, held in 1843, Mr. E. W. Binney first 

 announced his discovery of Stigmaria occupying the position of roots to Sigillaria, which induced the 

 present writer to bring before the public, in the ' Edinburgh PhOosophical Journal' for October 1843, an 

 outUne of his own views as contained in the paper already referred to, the publication of which 

 was commenced in the succeeding number, under the title of "Contributions towards estabUshing 

 the General Character of the Fossil Plants of the genus Sigillaria." It is necessary to mention these 



b 



