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XIII. On the Organization of the Fossil Plants of the Coal-measures. — Part III. Lyco- 
podiaceie ( continued ). By W. C. Williamson, F.B.S., Professor of Natural 
History , Owens College, Manchester. 
Received February 29, — Read March 7, 1872. 
In. the last memoir which I laid before the Royal Society I described a number of forms 
of Lepidodendroid plants from the Coal-measures, without making any material attempt 
to ascertain the relationship which they bore to each other. I now propose to carry the 
subject somewhat further, and to show that some of these apparently varied forms of 
Lycopodiacese merely represent identical or closely allied plants in different stages of 
their growth. The discovery of some remarkable beds in Burntisland, by Geoege 
Geieve, Esq., and his persistent kindness in supplying me abundantly with the raw 
material upon which I could work, have enabled me to do this in a manner, at least, 
satisfactory to myself. Upon the geology of these remarkable beds I will not now enter, 
beyond saying that they appear to have been patches of peat belonging to the lower 
Burdiehouse series, which are now imbedded in masses of volcanic amygdaloid. The 
stratum, where unaltered by contact with the lava, is little more than a mass of vegetable 
fragments, the minute structure of most of which is exquisitely preserved. The more 
perfect remains that are capable of being identified belong to but few types. The most 
abundant of these are the young twigs of a Lepidodendron, portions of the stem of a 
Biploxylon, stems of a remarkable Lycopodiaceous plant belonging to my new genus 
Dictyoxylon (but which, for reasons to be stated in a future memoir, I propose to unite 
with Coeda’s genus Heterangium , under the name of H. Grievii), and fragments of Stig- 
mctria ficoides. Along with these occur, but more rarely, several other curious Lycopo- 
diaceous and Fern stems, and those of an articulated plant, which I believe to be an 
Aster ophyllites ; also some true Lepidostrobous fruits and myriads of caudate macro- 
spores belonging to the Lepidostrobi. 
The first point to be noted is that all the Lepidodendroid branches are young twigs. 
No one example of a large stem has been found presenting exactly the same structure 
as these small branches, which, as already stated, are so abundant. On the other hand, 
all the Diploxylons are large branches or matured stems. These facts at once suggested 
the inquiry whether the two plants referred to might not be complementary to each 
other. A careful and very extended study of a large number of specimens has con- 
vinced me that such is the case. I have made more than a hundred sections of the 
two forms, and the result has been a remarkably clear testimony that the Lepidodendra 
are the twigs and young branches of the Biploxylon- stems. I am also led to the con- 
mdccclxxii. 2 Q 
