222 
PROFESSOR W. C. WILLIAMSON ON THE ORGANIZATION 
the most common of the Lepidodendroid strobili in the Lower Coal-measures of Oldham 
is a small one, of the central axis of which I have given a representation in fig. 59, enlarged 
two diameters, or in the same proportion as fig. 58. Of course I cannot affirm that the 
two are actually portions of the same plant ; but it is enough for my present purpose to 
indicate the possibility of such a relation. The correspondences of size, the similar 
central area in each, and the vascular ring surrounding that area present coincidences 
too striking to be overlooked. 
It will have been observed that I have said nothing about that remarkable form of 
Lepidodendroid plant, the Ralonia. The fact is, I have not been able to obtain speci- 
mens throwing any light upon this subject beyond what has already been done by 
Mr. Dawes. His figure and description, given in the Proceedings of the Geological 
Society of London for March 22, 1848, are so clear that there can be no difficulty in 
locating the plant in its proper place. The central axis consists of cells arranged as in 
my Plate XXVI. fig. 13, Plate XXY. fig. 14, & Plate XXVII. fig. 25, this is surrounded 
by a cylinder of barred vessels, as in fig. 13, from the outer surface of which the vascular 
bundles going to the bark are given off. 
The late Mr. James Wilde, of Oldham, published a notice in the 4 Geologist’ for 1863, 
p. 266, in which he states that a specimen of Lepidodendron with an Ralonia attached 
settles in the affirmative the question whether or not the latter is the root of the former. 
Through the kindness of Mr. Nield, in whose cabinet the specimen now is, I have had 
the opportunity of examining it, and conclude that it does no such thing ; it merely 
shows, what we knew before, that Ralonia is part of a Lepidodendroid plant. 
A fragment of an Halonia furnished to Mr. Dawkins by Mr. Whittaker, of Oldham, 
shows that the projecting tubercles which characterize Ralonia are of the same nature 
as the scars of JJlodendron which I have already described, viz. that they consist of the 
outer bark which has here pushed up into the epidermal layer, the latter being deflected 
along their sides. I have little doubt but that the Halonia was a fruit-bearing branch 
of a Lepidodendron, and that from each of the tubercles there was suspended a cone *. 
* Since the above was written, I have obtained a considerable amount of information on this subject. Two 
fine specimens in the Museum of the Manchester Geological Society, not only throw light upon the condition 
just described, hut also upon the relations of Halonia and JJlodendron. One of these specimens is a fine 
Halonia regidaris, of the usual type, but which is further invested with a thick bark, showing that the examples 
of this plant so commonly seen are semidecorticated ones, and that the characteristic tuberculated surface is not 
the outermost one. I may premise that my more recent investigations have compelled me to alter some of the 
terms applied in this memoir to the several parts of the bark, in order to bring them into harmony with what 
I find in recent Lycopodiacete ; consequently in a third memoir, recently laid before the Royal Society, I have 
designated the middle bark (h) of this paper the parenchymatous layer. The outer bark ( i and Jc) I have termed 
the prosenchymatous layer, and what I have called the epidermal (Z), I now designate the subepidermal layer. 
The detailed reasons for employing these terms ■will be given in the memoir referred to, meanwhile they may be 
applied to the specimens under consideration. In the new Halonia, the conical mammilliform tubercles 
evidently projected entirely through the prosenchymatous layer, and through a great part of the subepidermal 
one, a thin expansion of the latter alone appearing to invest the apex of the tubercle ; and even here there is 
a small central mucro which exhibits every indication that it accompanied something which projected entirely 
