SIGILLARLE AND STIGMARIA. 125 
SIGILLARLE AND STIGMARIZ. 
Among the most common and striking objects that arrest 
the attention of a person who visits a coal-mine for the first 
time, and examines the numerous vegetable relics that are 
profusely dispersed among the heaps of slate, coal, and shale, 
are long flat slabs, from half an inch to an inch thick, having 
both surfaces longitudinally fluted, and uniformly pitted 
with deep symmetrical imprints ; these are disposed with 
such perfect regularity between the grooves, that the speci- 
mens are often supposed, by persons not conversant with 
paleontology, to be engraven stones, and not natural pro- 
ductions. These fossils are the flattened trunks of gigantic 
trees covered by the bark in the state of coal; the regular im- 
prints on the surface, being the scars left by the separation 
of the petioles or leaf-stalks, as in the arborescent ferns pre- 
viously examined. The name Sigillaria, commonly applied 
to these fossils, is derived from sigil/wm, a seal, and alludes 
to the regular and uniform pattern of the imprints on the 
surface. These stems are from a few inches to several feet 
in diameter, and the largest attain a height of sixty feet ; 
they are generally found lying in a horizontal position in 
the strata, and quite flat, from the pressure produced by the 
superincumbent rocks; but when the trunks are in an erect 
position, and at right angles to the plane of the beds, the 
cylindrical form of the original is preserved. 
A remarkable instance, in which five stems of Sigillaria 
were standing upright, with their roots in the soil below, 
- apparently in the position in which they grew, was brought 
to light a few years since, in forming the Bolton and Man- 
chester railway.* They stand on the same plane, and near 
* These trees still remain in situ, and, thanks to the scientific zeal 
of Mr. Hawkshaw, have been carefully preserved. They are situated 
at Dixon Fold, Clifton, near Manchester. Instructive models of 
