418 VEGETATION OF THE CARBONIFEROUS PERIOD 



which quarters the base of the trunk. The Sigillaria generally divides 

 into four main roots at the base, which unite to form that crown of the 

 dome described by Lindley and Hutton ; and it is along the line of 

 union of these four roots that these strongly marked lines run, all 

 meeting at the centre of the dome. I know of nothing analogous to 

 this either in recent or fossil botany. 



Of the foliage of Sigillarice little or nothing is known ; the &. lepido- 

 dendrifolia* not appearing to be a typical, if at all a species, of the 

 genus. The scars are, especially in the larger species, much too broad 

 to be regarded as the point of attachment of leaves like those of Lepi- 

 dodendron. 



Internal Structure of Sigillarice. — The beautiful plate and excellent 

 description of the anatomy of Sigillaria elegans given by M. Brongniartf 

 are, though as regards the specimen most satisfactory, far from com- 

 pleting our knowledge of the genus. The drawing of the entire plant 

 is evidently not that of a fluted Sigillaria of the common form. It may 

 belong to a young plant of this genus upon which the organs indicated 

 by the scars were very closely packed ; but this is a supposition only ; 

 and until the figured fossil is better known, or some of the fluted species 

 are found to contain structure, we must hold that the tissues of Sigil- 

 laria proper are to be described. M. Brongniart's plant is no doubt 

 allied to this genus, and very distinct from Lepidodendron : there is a 

 probability, too, of its belonging to the same plant as Stigmaria, which 

 is evidenced by the similarity of the arrangement of the vascular 

 tissues in both. This tissue in Stigmaria is broken into wedges, indi- 

 cating a higher organization than is found in Lepidodendron, and a 

 still more complex arrangement in the trunks of which Stigmaria are 

 the root. Such we find in M. Brongniart's S. elegans, wherein are 

 two distinct series of bundles of vascular tissue ; one disposed in 

 wedges separated by medullary ? rays, J the other in as many bundles, 

 each placed at the back or small end of one of these wedges. 



The great bulk of Sigillaria seems to have been inimical to the pre- 

 servation of their tissues, the process of decay being generally effected 

 on a grand scale in the substance of a plant evidently almost entirely 

 composed of a lax tissue. The remains of a central column are, 

 however, sufficiently obvious in the upright stems of mariy Sigillaria, 



* « Brongn. Hist. Veg. Foss.," p. 426, t. 161. 



+ " Archives du Musee d'Hist. Nat." vol. i. p. 404. 



J The tissue of the axis of this plant and of its rays is wanting. This is generally 

 the case in the spaces corresponding to what are filled with cellular tissue in analogously 

 formed vegetables. In all carboniferous fossils that I have examined the cellular tissue 

 is best preserved at the coaly circumference. I have, however, observed it elsewhere; and 

 in one Stigmaria it occupies nearly all the broad space intervening between the circum- 

 ference and vascular column. 



