1848.] DAWES ON THE INTERNAL STRUCTURE OF HALONIA. 289 
1. Remarks upon the Internal Structure of Wauronta. 
By Joun S. Dawes, Esq., F.G.S. 
Ir was proposed by the authors of the ‘ Fossil Flora’ that the genus 
Halonia should comprehend all those plants combining the surface of 
the Lepidodendra with the mode of branching of the Coniferze, to which 
latter order they considered these fossils to be analogous. The dis- 
covery, however, of better-preserved specimens has clearly shown that 
the supposed remains of alternate branches, noticed more particularly 
upon one species, the H. gracilis, must have been merely impressions 
of the protuberances which characterize these fossils, and that they 
are in fact, like the Lepidodendra, dichotomous. A still further proof 
of cryptogamic affinity is now afforded by sections of a specimen from 
the neighbourhood of Birmingham, in which traces of the vegetable 
structure have been preserved. By reference to the drawing fig. 1, it 
Fig. 1. 
aa 
: sates ree 
§=(sea5 
PoC 
cautsiatengs 2 1 
Seedneements 223) /iese 
a b c d e 
will be seen that this stem is composed of a central medullary column 
(a), surrounded by a series of scalariform vessels (4), these being 
succeeded by a compact cellular tissue (c), which becomes more lax 
between this central part and the cortical zone, the latter (d) being 
composed of a thick-membraned, very regular tissue, and bearing a 
large proportion to the rest of the stem, equal in some specimens to 
one-third of the diameter. There are no concentric rings, or, strictly 
speaking, medullary rays, neither any ligneous fibre, or indeed any 
indication whatever of affinity with the Conifere, or even with that 
division of Dicotyledons, except that some similarity exists in the 
character of the striated tubes which surround the medullary column, 
and the pseudo-vascular bundles of certain Zamize. Neither are these 
plants to be referred to that class which includes the Sigillaria, Ana- 
bathra, &c.; for although the structure in some important respects 
may correspond, the arrangement of the tubes of the vascular system 
is altogether reversed ; consequently the curved scalariform bundles 
which traverse the stem from its axis to the periphery do not emerge 
from the tissues immediately in connection with the medullary 
column, but are thrown off from the outer portion of the sheath. 
These leaf-cords, which appear somewhat to resemble the stem in 
miniature, take a direction for some distance nearly horizontal, so 
