378 PEOFESSOE W. C. WILLIAMSON ON THE OEGANIZ AT ION 
To the plant thus described Mr. Binney gave the name of Dadoxylon Oldhamium. 
The above object came under my notice at an early period of my investigations 
amongst the plants of the Coal-measures, and I soon became convinced that it was not 
a Dadoxylon. In a brief memoir published in the ‘ Monthly Microscopic Journal ’ for 
August 1869, I pointed out that, since the appearance of Endlicher’s memoir on 
Dadoxylon, “numerous specimens of woody stems have been found, transverse sections of 
which exhibit a structure identical with that of living conifers ; but longitudinal sections 
show that the vessels or fibres are altogether different from the coniferous or discigerous 
type. Instead of bearing rows of disks, and those only on the surfaces of the vessels parallel 
with the medullary rays, their entire walls are covered with reticulations formed by the 
deposition of lignine in the interior of the vessels.” Then, after describing some figures, 
I proceeded to say, “ These two figures represent reticulated fibres as seen in several 
distinct plants found in the Coal-measures. Whether these prove to be different species 
of one genus, or whether they will require more than one genus for their reception, 
remains to be seen. But certainly none of them can be regarded as Dadoxylons, since 
they belong to an altogether different type of structure.” 
“ It appears necessary, therefore, to establish a new genus for all the plants whose 
woody cylinders consist of reticulated fibres, and the name of Dictyoxylon appears an 
appropriate one for it. I should propose for the present to include in this genus all 
the reticulated types, whether their medullary rays consist of one or of several vertical 
series of cells. At some future time their further separation into two or more genera 
may be requisite.” 
The memoir from which the above quotations are taken contains two errors — one of 
observation, and one due to a misprint. In some examples, in which the structure was 
imperfectly preserved, I found it difficult to distinguish the lenticular disks of the 
supposed conifer Dadoxylon from the reticulated areolse of the Dictyoxylons. The two 
specimens numbered 7 and 1 1 in the Plate illustrating the memoir had their vessels in 
this imperfect condition, and I fell into the error of regarding them as Dictyoxylons. I 
have since ascertained, beyond doubt, that they are both Dadoxylons*. The second 
error is a misprint of Dictyoxylon for Dadoxylon in the eleventh line from the end of 
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the memoir. As it stands, the supposed coniferous fruit known as Trigonocarpon is 
indicated as possibly belonging to the former genus, whereas I intended to suggest the 
possibility of its relation to the latter one. 
At the Edinburgh Meeting of the British Association in 1871, I described yet more 
definitely the characteristics of my genus Dictyoxylon, especially as represented by three 
plants, viz. Mr. Bixney's Dadoxylon Oldhamium, a new species from Burntisland to 
which I gave the name of Dictyoxylon Grievii, and a third form from the Lancashire 
Coal-measures, to which I assigned the name of D. radicans. Further investigation into 
the history of the latter plant has led me to separate it from Dictyoxylon, under the 
* The correction of this error is important, since fig. 11, especially, represents a plant with a Sternhergian 
pith, whereas no such pith occurs in any known true Dictyoxylon. 
