File:The Quarterly journal of the Geological Society of London (12645690054).jpg

1849..
BROWN ON ERECT SIGILLARI^.
355
I have now the satisfaction of forwarding sketches and descriptions
of two curious fossils from the roof of the main coal, calculated in my
opinion to afford some interesting information concerning the habit
and mode of growth of Sigillaria alternans ; and at the same time
to clear up all doubts respecting the true nature of the " dome-shaped
fossil," figured and described in Lindley and Button's ' Fossil Flora,'
vol. ii. pref. p. xiii.
Fig. 1.
c,
stump of Sigillaria alternans, one-twelfth of the natural size.
Fig. 1 is a sketch of an upright stump, sixteen inches in height
and twelve inches in diameter at the top, which dropped from the
roof of the seam some time after the coal had been removed ; the
greater part of the branching roots had fallen do^vn and been stowed
aw^ay amongst the rubbish of the mine before the stem was discovered ;
the few that remained are in external appearance true Stigmarise, but
being filled up with soft shale, no traces of internal organization can
be observed, except occasionally a flattened central core. The upper
part of the stem was covered with a coaly bark one-fifth of an inch
in thickness, which was closely marked with irregular short striae in
a vertical direction, and by long projecting wrinkles running spirally
round the stem as shown at c (fig. 1). A thin layer of hard shale
which envelopes the bark, completely conceals the leaf- scars. Lower
down the bark was thinner and very smooth, whilst that which
covered the roots a, h was so exceedingly thin and friable, that it
fell off on the slightest touch.
The leaf-scars on the decorticated stem are very sharp and distinct ;
they begin close to the ramifications of the roots, and run in single