Notes . 
318 
wood is a zone of radially arranged tissue, evidently of secondary origin, and 
occupying the place of the secondary xylem. I have not, however, been able 
to detect any tracheides in this zone, which appears to be wholly parenchymatous, 
except of course where the leaf-traces pass through it. The presence of this 
parenchymatous zone is characteristic of the type of stem commonly referred to 
Lepidophloios fuliginosus ; in some specimens of the latter type groups of secondary 
tracheides are embedded in the secondary parenchyma, while in other cases the 
structure has been found to be entirely parenchymatous, as in the fine Halonial 
branch which Professor Weiss refers to Lepidophloios fuliginosus 3 I have found the 
specimens in my collection extremely variable in this respect, the tracheides, where 
they appear, being sometimes quite local in their occurrence. 
The phloem-zone in our specimen of Lepidodendronobovatum is imperfectly pre- 
served ; beyond this we come to the inner cortex, a comparatively narrow zone of dense, 
small-celled tissue; outside this the broader middle cortex is partially preserved, and 
consists of a delicate tissue of relatively large cells. The outer cortex has a firmer 
structure, resembling the inner cortex in this respect, but with rather larger cells. The 
leaf-bases present the usual structural features — vascular bundle, parichnos, and ligular 
pit. Within the leaf-bases the zone of periderm, usual in Lepidodendreae , is well 
developed ; in branch A a second peridem, internal to the first, is present locally. 
The leaf-traces are met with in all parts of their course from the stele to the 
leaf-bases; they are often well-preserved, and show exactly the same structure as 
lias been figured in stems referred to Lepidophloios fuliginosus . 1 2 The presence, 
on the phloem-side of the strand, of the dark mass or crescent, interpreted by 
Mr. Seward as secretory tissue, is a striking point of agreement. 
In branch A there is a specially interesting feature in the presence of a small 
lateral stele, which, in the three transverse sections of this specimen, is shown at 
three points of its outward course. The small stele has a somewhat horse-shoe form 
at first, gradually closing up into a circle as it passes further outwards. The wood 
appears to enclose a small pith, and leaf-traces are given off while the stele is 
still on its way through the parent cortex. There is a very marked resemblance to 
the steles supplying Halonial tubercles, as shown, for example, in Professor Weiss’s 
specimen. The main stele remains open on the side from which the lateral stele 
has been given off, the gap becoming narrower upwards, but not closing within the 
region from which sections have been cut. 
The most striking point about the structure of the stem of Lepidodendron 
obovatum is its close agreement with that of Lepidophloios fuliginosus. If the 
specimen had been found in the usual condition, without superficial characters, 
it would beyond doubt have been placed in the genus Lepidophloios, if not in the 
species L. fuliginosus. The fact that our stem is clearly referable to a typical species 
of Lepidodendron shows that external and anatomical characters do not necessarily 
correspond in the Lepidodendreae, and warns us that all identifications of Lepidophloios 
1 F. E. Weiss, A Biseriate Halonial Branch of Lepidophloios fuliginosus, Trans. Linn. Soc. 
London (Bot.), vol. vi, 1902, p. 225. 
2 Seward, Notes on the Binney Collection of Coal-Measure Plants, Part I, Lepidophloios. 
Proc. Cambridge Phil. Soc., vol. x, 1899, PI. Ill, Figs. 1 and 2. Weiss, 1. c., PI. XXV, Fig. 13. 
