231 PROF. F. E. WEISS ON A BISERIATE HALONIAL 
WirLiAMsox, W. C. (1887).—Note on Lepidodendron Harcourtii and Lepidodendron fuliginosum (Will.). 
Proc. Roy. Soc. vol. xlii., 1887. 
WiLLiAMsoN, W. C. (1889).—Organization Ee, Part XVI. Phil. Trans. ser. B, vol. 180 (1889), 1900. 
WirLrAMsox, W. C. (1893).—Organization &c. Part XIX. Phil. Trans. ser. D, vol. 184 (1893), 1894. 
EXPLANATION OF PLATES 23-26. 
Pl. 93. fig. 1. Photograph (nat. size) of the halonial branch of Lepidophloios fuliginosus, showing the 
two rows of tubercles. Near the upper and lower ends the periderm is preserved ; 
where the latter is absent, the leaf-traces are seen forming small elevations in the 
cortical tissues. | 
The photograph is by Messrs. Gunn & Stuart, of Richmond. 
PL. 93. fig. 2. Photograph (2 nat. size) of an halonial branch in the Manchester Museum, from the 
Four Foot Mine at Tonge, near Bolton. One of the two rows of tubercles is here 
visible, but no remains of the leaf-bases. 
Pl. 23. fig. 3. Photograph of the other side of the halonial branch depicted in fig. 2, showing the 
other row of tubercles, aud near the top right-hand side the traces of bifurcation. On 
this side are seen the carbonized remains of the leaf-bases, showing that these were 
of the Lepidophloios-type. 
Pl. 23. fig. 4. A portion of the leaf-bases of the halonial stem illustrated in figs. 2 & 3, somewhat 
enlarged to show the downward imbrication of the leaves. 
Pl. 24. fig. 5. Photograph of an halonial branch from the Williamson Collection (British Museum), 
cabinet-number 1946 g, showing imbricating leaf-bases and two rows of tubercles. 
Pl. 24. fig. 6. Transverse section (slightly enlarged) of the halonial branch of LepidopAloios described 
in this Memoir, showing the general arrangement of tissues. The stele is interrupted, 
having just given off a branch (b) to one of the tubercles. 
i.c. — inner cortex. 
m.c. = the middle cortex, with horizontal leaf-trace bundles. 
0.C. = outer cortex. 
per. — periderm. 
Pi. 24. fig. 7. Enlarged view of stele of halonial branch. 
m. — medulla. 
p.x. = primary xylem. 
s.t. = secondary tissues. 
ph. — phloem. 
i.c. — inner cortex, with leaf-traces. 
6. = vascular branch. 
Pi. 23. fig. 8. Portion of phloem in longitudinal section, showing transverse walls (tr.w.) across the 
lacunz formed by a breaking down of the phloem-cells, 
Pl. 26. fig. 9. Portion of transverse section, showing phloem 
-area (ph.) occupied by small-celled tissue, 
before decay of latter. 
