BRANCH OF LEPIDOPHLOIOS FULIGINOSUS. 219 
specimen would not be an halonial but a ulodendroid branch, and therefore not referable 
to the genus Lepidophloios. 
Thus Kidston (1893), in his memoir on ZepidopAio?os, states: ** If it is necessary to 
define a difference between the Ulodendron-condition and the halonial condition even in 
the absence of the bark they can be separated, the former having two rows of alternate 
(usually) cup-shaped scars, the latter having more than two rows of (usually) conical 
tubercles spirally arranged.” 
On the other hand, Williamson in the same year (1893), after discussing at some length 
the various specimens of Halonia and Ulodendron known to him, comes to the conclusion 
* that the only distinction between halonial and ulodendroid conditions lies, not in the 
number or arrangement of the fruit-scars, but in the presence or absence of a pressure- 
disk surrounding each fruit-scar." 
It will be seen from these two definitions that the halonial condition is according to 
Williamson a very different thing from the halonial condition defined by Kidston, 
the latter basing his definition on the number of rows of scars or tubercles, while 
Williamson disregards their number but distinguishes the elevated tubercles of Halonia 
from the cup-shaped pressure-disks of Ulodendron. 
In calling the specimen under consideration an halonial rather than a ulodendroid 
branch, it will be seen that I incline to Williamson’s view that the elevation of the 
tubercles is a more distinctive feature than their number or arrangement. 
I cannot believe that absence or presence of an elevation is due merely to presence or 
absence of pressure during mineralization or to absence or presence of a well-preserved 
covering of leaf-bases. A number of fruiting-branches of Lepidophloios are known with 
the leaf-bases well preserved still showing fairly prominent tubercles, though of course 
in “ decorticated " specimens the tubercles are more prominent*. Similarly, in an 
Halonia which has evidently been much compressed the tubercles are clearly dis- 
tinguished, even on the surfaces which have been most exposed to pressure. PI. 23. 
figs. 2 & 3 of the present memoir show the two sides of the same halonial branch, which 
exhibits distinct tubercles on one side (fig. 2), while on the other (fig. 3) the branches 
have the character of flattened or cup-shaped areole. This difference depends on 
differences of position or condition during mineralization. 
I would therefore describe the “ halonial condition” as the fruiting-branch of Lepido- 
phloios bearing a number of more or less elevated tubercles either in quiucuncial or in 
biserial arrangement. 
'This description of the halonial branch would agree in general with that given by 
Williamson (1893), and would also agree in this particular with the views expressed by 
Kidston (1886 and 1893) and by Potonié (1893 and 1899), that, so far as is at present 
known, the halonial condition is restricted to the genus Lepidophloios. On the other 
hand, the view I have adopted differs from that held by Kidston and Potonié in not 
* The term “ decorticated," so much in use in the description of halonial branches, is misleading, for it has not 
been employed to describe stems in which the cortex is absent but in which the leaf-bases or cushions are worn 
away and in which consequently the leaf-scars are not distinguishable. Thus the specimen under examination 
would be termed ** decorticated," whereas even the outer cortex is completely preserved. 
212 
