[PENHALLOW] OSMUNDITES SKIDEGATENSIS 15 
other parts, this zone in the fossil must have had an external diameter 
not far from 64 mm. 
The cells of this tissue are rounded, rather small, and thick-walled. 
The region is traversed by numerous leaf traces which now partake more 
fully of the organization of the future stipe. By comparison with the 
fossil, it is possible to understand the highly carbonaceous character 
which this region presents in the latter. 
TODEA BARBARA. 
The large external diameter of the stems of Todea barbara suggested 
the expediency of a comparison with it In this plant the short upright 
stems are about 24 cm. long and 11°5 cm. broad. They are joined into 
a massive trunk nearly three feet in diameter and about the same height. 
A transverse section discloses the fact that the external dimensions bear 
no relation to the size of the central axis or stem proper, and therefore 
in that respect it fails to throw light upon the character of the fossil. 
From what may be regarded as equivalent to the upper side of the rhi- 
zome in Osmunda, the stipes diverge from the stem at an angle of 20°, 
while from the opposite side—that which is outermost in relation to the 
whole trunk—they show a divergence of 35°, this angle being greatly 
increased toward the outer limits of the stem by a continually increasing 
curvature. It will thus be seen that this divergence is at least twice as 
great as in the fossil, twice as great as in Osmunda cinnamomea, and 
one-fourth greater than in O. regalis. This seems to explain the marked 
differences of external dimensions where the central axis is approximately 
the same. 
The Pith.—The pith has an external diameter of 1:5 mm. It shows 
but few radial extensions into the xylem of the stele. 
Medullary Rays.—The medullary rays are few in number, but they 
present essentially the same features as in Osmunda. 
The Stele.—The stele is composed of a few broad vascular bundles.1 
The xylem only occasionally exhibits the horseshoe form so well defined 
in Osmunda. The phloem shows essentially the same features as in 
Osmunda, except that the outer layer in the endodermal region consists 
of very much elongated (tangentially) cells, in this respect differing 
materially from Osmunda and closely approaching the type exhibited in 
the fossil. (Plate VI., fig. 12.) The stele as a whole has an outside 
diameter of 3 mm., with an average thickness of 0°75 mm. It is 
therefore closely comparable with the two species of Osmunda already 
described. 
1 De Bary, Comp. Anat. of Phan. & Ferns, 347. 

