Weiss. — A Stigmaria with Centripetal Wood. 227 
from the calciferous sandstone of Dalmeny, described by Seward and Hill 
(’99). In Fig. 21 , Plate III of their memoir, such a constricted bundle 
is seen lying, applied there to the secondary wood, which seems almost 
to take the place of the reticulate cells of our Stigmaria . Indeed, the 
tangential view of the inner portions of the secondary wood in Fig. 23 
of Seward and Hill’s memoir very closely resembles these tracheids. 
Whatever the functions of these reticulate tracheids may have been in this 
case, we may well institute a comparison between them and the transfusion 
tracheids met with in the leaves of the Lepidodendraceae and in the 
Coniferae, where, as in Torreya and some other forms, they have, according 
to Bernard (’04), reticulate markings. But a comparison with a leaf-trace 
does not upset the conclusion that these are rootlet bundles, for tracheids 
corresponding with transfusion cells, though differing in function, are found 
in the rootlets of Stigmaria. (See Weiss, ’03.) 
Traces of the vascular bundles may be seen, though somewhat in- 
distinctly, making their way through the periderm layer to the exterior. 
Fig. 8 , PI. XV, represents one of these cases from a longitudinal section, 
showing a vascular bundle (v. b.) passing out accompanied by a strand of 
small parenchymatous cells. This, which undoubtedly represents a parichnos 
strand, i. e. a portion of the mid-cortex, passing through the periderm, does 
not preclude the identification of the axis as of Stigmarian nature, for, as I 
have shown elsewhere (Weiss, ’07), parichnos strands are not found exclu- 
sively in connexion with the leaf-trace bundles but also with rootlet bundles. 
And this I am satisfied is the character here, as the parichnos strand 
narrows down considerably to the outside, where the rootlet cushion would 
be found. Unfortunately the external tissues are very badly preserved, and it 
is difficult to identify the external process, though I believe it to be a 
portion of a rootlet. 
It remains for me to sum up the arguments in favour of regarding the 
specimen under consideration as a Stigmarian axis rather than a stem 
of Lepidodendron mundum , as Williamson had concluded from a more 
fragmentary and less well-preserved specimen. 
In the first place the very wide periderm (see Fig. 1 , PI. XV) and its 
peculiar structure (Fig. 8 , PL XV), together with the remains of what must, 
I think, be taken to be rootlet cushions, speaks in favour of the Stigmarian 
nature of these tissues ; while the absence of primary outer cortex of hard 
texture distinguishes it from the stem of Lepidodendron mundum. 
In the curious centrical lateral bundles (Fig. 1 , PI. II) and in the posses- 
sion of a system of delicate reticulate cells (see Figs. 6 and 7 , PI. XV) this 
axis agrees more closely with the Stigmaria Brardii of Renault (’93) than 
with any Lepidodendroid stem, not excepting the possible Lepidophloios 
Harcourtii from Dalmeny, described by Seward and Hill (’99). It must 
be remembered, however, that the reticulate cells of the French specimens 
