258 Weiss. — A Mycorhiza from the Lower Coal-Measures. 
in that respect, as well as in others to which reference will be made later 
on, the stele resembles somewhat that of the rhizome of Psilotum. It 
is true that in this latter plant the xylem-rays, whether two or more, are 
generally connected in the centre ; but in certain parts of the plant, accord- 
ing to Bertrand’s (’ 82 ) figures and description, the xylem- groups may 
remain separate. Owing to the uncertainty as to the position of the proto- 
xylem, I prefer, therefore, to leave it an open question whether the organ 
under consideration was a root or a rhizome. If the latter, then it must have 
Fig. 42. Enlarged drawing ot stele from specimen represented in Fig. 2, PL XVIII. The 
protoxylem elements (fix) are on the outside of the groups of wood. The ground tissue is filled 
with granules (starch ?). The stele is surrounded by a distinct endo-cortex (eri) within which 
is a phloem-sheath L? .). 
been a leafless rhizome of the type found in the Psilotaceae or in Corysantkes, 
Corallorhiza , and some other Saprophytes. 
In longitudinal section, as seen in Plate XVIII, Fig. 3, which is taken 
from Dr. Scott’s specimen, it will be seen that the xylem consists mainly of 
scalariform tracheids. I have in fact not been able to discover any other 
elements in the longitudinal section ; but it is of course possible that the 
latter did not pass through the spiral elements if such were present in the 
plant. There are no very clearly-marked phloem elements, though certain 
cells on either side of the xylem-groups might be considered as bast cells 
{ph). In this respect we have another agreement with Psilotum and also 
with other Lycopodiaceous plants in which the phloem is not made up of 
well-defined sieve- tubes. Similarly in some cases, as in Plate XVIII, Fig. 2, 
