BRANCH OF LEPIDOPHLOIOS FULIGINOSUS. 223 
II. ANATOMICAL STRUCTURE. 
The identification by Dr. Scott (1898) of the halonial branch under consideration as 
belonging to Lepidophloios fuliginosus will be confirmed by tbe details of the structure 
which will now be given. 
The general view of the transverse section (Pl. 24. fig. 6) will be seen to resemble 
in its chief features the Lepidodendron fuliginosum (previously called Harcourtii), 
figured by Williamson (1881) in Part xr. of his * Organization of the Fossil Plants of 
the Coal-Measures” (see pl. 52. fig. 9). Our specimen differs from Williamson’s 
in the better preservation of the mid-cortex, which is practically perfect. This 
difference in preservation is doubtlessly due to a difference in the minute structure 
of this tissue. "Though with small magnification there appears to be a considerable 
* uniformity in the composition of the entire cortex," as Williamson states (p. 7), yet 
there is, as we shall see on closer examination, a very considerable difference between 
the inner, the middle, and the outer cortex. 
Another feature which distinguishes at a glance the specimen under consideration 
from Lepidodendron Harcourtii is the course of the leaf-trace bundles through the mid- 
cortex. It will be seen that these run very obliquely through this tissue, at times indeed 
nearly horizontally, as is especially the case in the bundles running in the direction of 
the longer diameter of the elliptical section. "This character is more frequently found in 
Lepidophloios fuliginosus than in other Lepidodendra, and is certainly characteristic of 
that specimen to which Williamson first gave the specific name of fuliginosus; for it is 
to the specimen figured in plate 51 (fig. 10) of Part xr. that he referred in his note of 
1887, when he introduced this new specific name, and in that specimen the leaf-trace 
bundles run very nearly horizontally through the middle cortex. 
Other specimens of Lepidophioios fuliginosus in the collections of the Manchester 
Museum also show this very horizontal course of the vascular bundles; and I would like 
more partieularly to mention one in the Wilde Collection (No. 158) which is labelled 
an halonial stem, and which, from its more circular outline and smaller dimensions, 
I think must have belonged to a multiseriate «lonia. That it is an halonial stem is 
indicated by the branch which is given off from the central vascular cylinder. The 
uniformity, both in respect to the course of the leaf-trace bundles and to the detailed 
structure of the cortex and other tissues, convinces me that no distinction can be made 
anatomically between this specimen and that under consideration. j 
Another feature which is characteristic of LepidopAloios fuliginosus is the peculiar 
formation of the secondary tissues formed around the primary xylem cylinder. This, 
as is seen in Pl. 24. fig. 7, Pl. 25. fig. 11, and Pl. 24. fig. 12, is of almost precisely 
the same nature as that figured by Williamson (Part xr. pl. 49. fig. 11) as the 
* rudimentary exogenous zone." 
After these general observations, we will pass to a detailed consideration of the 
tissues. 
