132 THE MEDALS OF CREATION. Cap. VI. 
disposed in a radiating manner, and traversed by fibro- 
vascular bundles, which pass towards the leaves. 
Upon instituting a comparison between the fossil and the 
stems of those recent plants which present the closest 
analogy to it, M. Brongniart was led to conclude that the 
Sigillarie constituted a peculiar extinct family, belonging to 
the great division of gymnospermous dicotyledons. 
The Sigillariz were tall erect trees, with a regular and 
cylindrical stem, without side branches, but dichotomous 
towards the summit. Their superficial bark was hard and 
durable, channelled longitudinally, bearing leaf-scars that 
are of a rounded form above and below, and angular at 
the sides, often oblong in relation to the stem, and having 
three vascular pits, one central and small, and two lateral of 
a larger size. The internal structure bears most analogy to 
that of the Cycadez, and the foliage consisted of long linear 
carinated leaves. The Sigillarice, therefore, differ essentially 
from the arborescent cryptogamia, which they somewhat 
approach in having scalariform vascular tissue, symmetrical 
and regular leaf-scars, and branchless trunks. More than 
fifty species have been determined,* 
Stiemarra. Lign. 36.—This extended notice of the 
structure of the Sigillariz, will enable us to understand the 
nature of the fossil vegetables termed Stigmarie, or spotted- 
stems, which abound in the beds of under-clay of most coal- 
fields, as stated in a former part of this work (ante, p. 81). 
These bodies when uncompressed are of a cylindrical form, 
from one to six or seven inches in diameter, and of consider- 
able length—sometimes upwards of twenty feet—and gra- 
dually diminish in size towards their termination. The surface 
is marked with distinct pits or areole, of a circular or oval 
form, with a small tubercle in the centre of each, disposed 
around the stem in a quincunx and somewhat regular order. 
* For figures of Sigillariz, see Pictorial Atlas, pl. xix. xx. xxiv. 
