468 
PROFESSOR W. C. WILLIAMSON ON THE ORGANIZATION 
diameter have the hollow ones, inclines me to adhere to my former opinion that these 
differences are merely due to age : a conclusion strengthened by the fact that solid 
axial bundles are equally absent from every specimen of considerable size that we 
have as yet obtained from any British locality. At the same time it is possible that 
this opinion may some day require modification. 
The late Mr. Binney held the view that the Halonice were the roots, and not the 
branches, of some Lepidodendroid plants. M. Renault, in his recent ‘ Cours de 
Botanique Fossile,’ advocates the view that some Ilalonice are -what he terms 
“ Stigmarhizom.es ” or semisubterranean creeping stems. Structural evidence compels 
me to reject both these conclusions.* Mr. Carruthers arrived at the same conclusion 
as I had done from his study of some specimens which he described in 187S.I 
Recently visiting the museum of the Leeds Philosophical Society, I found on their 
shelves the magnificent and most conclusive specimen of a branching Lepidodendron, 
the terminal subdivisions of which are true Halonice, represented in fig. 26. I am 
indebted to Professor Miall for an excellent cast of this specimen, from which cast 
Mr. Brothers, of Manchester, prepared the beautiful photograph copied in the above 
figure. It is yet more perfect than Mr. Carruthers’ specimen, since its lower 
extremity, a, exhibits much more markedly than his corresponding ones do the 
elongated foliar cicatrices characteristic of the Lepidodendra. At the lower portion of 
the branch, A, these leaf-scars have exactly the same form as those of L. selciginoides 
and L. elegans of Lindley and Hutton. After its first bifurcation, the two branches, 
B, B, still retain much of their Lepidodendroid features, though the leaf-scars 
gradually become less elongated vertically. Towards the upper part of each of the 
branches, B, B, we discover the first traces of the tubercles characteristic of Halonia. 
These become yet more conspicuous and numerous in the terminal branches, C, C, 
where we also find that the foliar cicatrices are equilateral rhomboids, instead of the 
vertically elongated scars seen at A; their vertical and transverse diameters being 
now about equal. The difference between the two forms is shown to be due in this 
instance, not only to differences between the several cortical layers, but to the fact that 
these branches, like their parent stems, have grown more in length than in breadth. 
This is proven by the circumstance that we can trace the gradations from the one 
form to the other in the same continuous cortical surface. These Halonioid branches 
are obviously identical with the Halonia tortuosa of Lindley and Hutton. 
* See memoir, Part II., p. 222, Phil. Trans., 1872. In the work referred to above, M. Renault 
endeavours to draw a distinction between Halo7iice, which he believes to be the subterranean rhizomes, 
and those which he recognizes as branches of Lepidodendron. He includes in the former class, which 
he thinks differs from his second one in the rarity with which dichotomous branching occurs in the 
Halonice belonging to it, the well-known Halonia regularis. This distinction is a purely imaginary 
one. Halonia regularis dichotomises freely.—July 7th, 1883. 
t “ On Halonia of Lindley and Hutton and Cyclostadia of Goldenbekg,” Geol. Mag., vol. x., No. 4, 
April, 1873. 
