Feb., 1889. 
STIGMARIA. 
81 
ironstone, or occasionally wholly of pyrite, have been formed? 
In short, are they not just as likely to be of concretionary 
origin (replacement of organic vegetable matter by iron), as 
they are to be due to infilling from the roof of the seams ? * 
8.—With regard to the shape of the fossils : Do not their 
rounded-off terminals (resembling in many cases that of a 
cucumber), as well as the peculiar serpentine or folded aspect 
of many of them, demand some other explanation of their 
form than that which supposes them one and all to be the 
result of chemical alteration combined with pressure brought 
on during solidification of vegetable matter into coal ? (Plate 
IL, figs. 2 and 5.) 
4. —Had these Stigmarise been tree roots, how is it that all 
traces of the stems or stools have disappeared ? Why were 
none of them preserved as sandstone casts if that were the 
case with the roots ? 
5. —Another botanical point : Is it not just as logical to 
say :—As Stigmaria was the root of at least two different trees 
(Sigiliaria and Lepidodendron). and that as Lepidodendron 
branches sometimes terminated in Halonia, what is there to 
prevent us from allowing that Stigmaria may sometimes have 
existed without any upright or aerial stem at all ? 
6. —In regard to beds of coal: Inasmuch as it does not 
appear that the roots of Sigiliaria, &c., have been shown to be 
Stigmaria from the stuav of specimens found in underclavs ; 
liow can it be said that the Stigmaria-looking fossils in these 
clays had a similar organisation to the tree-root Stigmaria, or 
that they were ever really roots at all ? 
7. —In what other way are we to account for the fact of 
the Little Flint coal in Coaibrookdale resting, not upon an 
underclay, but directly upon a bed of sandstone in which it 
is stated there are no Stigmariae at all, except we conclude 
that the coal did not commence to grow as a forest of trees, 
&c., or that it was an aqueous formation?! 
* It lias always appeared a difficulty with me in accepting the idea 
held by many of us, that when we find Stigmarise as tree-roots many 
yards in length, and in the shape of complete casts of the roots, 
composed entirely of Sandstone, the sand must of necessity have come 
in through the stump of the tree and found its way along the roots to 
their terminals, filling up the roots gradually toieards the stump. That 
a decayed tree root, whether it grew in what is now coal or in sand, 
could be so filled, seems to my mind, an impossibility. I look upon 
these fossils as having been formed by infiltration of siliceous matter 
through their outer bark or coatings—a gradual replacement of wood 
tissue by mineral matters. 
f Not necessarily transported by water, but certainly not grown on 
dry land. 
