OF THE FOSSIL PLANTS OF THE COAL-MEASHEES. 
3 
me in following M. Renault’s example, assuming the desirableness of abandoning 
Corda’s name of Palmacites as misleading in this instance, *and Cotta’s term Medullosa 
as belonging to the other species of his genus. 
Examples of very young or terminal rachides of Myelopteris are not uncommon, since 
Mr. Butterworth and the late Mr. Whittaker have added specimens of such to those 
which I have collected myself. More matured petioles are much more rare. In addi- 
tion to two or three which I have met with, I have received one very fine section from 
Mr. Butterworth, and Captain J. Aitken, of Bacup, has placed in my hands an inter- 
esting example ; but none of these rival in magnitude the examples from Chemnitz and 
Autun. M. Renault has kindly supplied me with a beautiful specimen from 1 the latter 
locality. 
Fig. 1 represents a transverse section of a petiole, for which I am indebted to 
Mr. Butterworth. The section is half an inch in diameter in one direction and yh in 
the other. It consists of a mass of parenchyma (a), the cells of which vary in diameter 
from -006 to others of very much smaller dimensions, encased in a cortical investment 
(5), whilst scattered over the section are numerous gum-canals ( c ) and vascular bundles 
( d ). The figure represents this section enlarged ten diameters. Though I have no lon- 
gitudinal section of this individual example, I have such sections of similar ones which 
must be studied along with it. Fig. 2 represents a longitudinal section of the central 
part of a similar specimen to fig. 1, but enlarged 20 diameters. From this latter section 
we find that the cells of the medullary parenchyma ( a ) are arranged in more or less 
vertical lines, as is usually the case amongst Ferns, though, as seen in the figure, they 
are subject to much variation in this respect : this vertical arrangement is due to the 
tendency of the parallel walls of the cells to arrange themselves at right angles to the 
long axis of the petiole, a condition well shown in fig. 8. 
Figs. 3, 4 & 4* represent three very young, or rather, perhaps, they may he termed 
terminal portions of the branched rachis. At the first glance these sections appear 
altogether different from fig. 1 ; but the differences are but apparent, since an unbroken 
series of links connects the two conditions, and shows that fig. 1 is but a more developed 
condition of fig. 3. Fig. 5 is a longitudinal section of a yet smaller rachis of the same 
kind as figs. 3 & 4, but giving off lateral branches (A), which are probably the petioles'of 
leaflets. This figure is enlarged 16 diameters, the original specimen being little more 
than -06 in diameter. 
In the size and arrangement of their parenchymatous cells these several examples 
vary but little from what I have just described. In the young or smaller branches of 
the rachis (figs. 3 & 4), the most conspicuous objects are longitudinal canals, which 
appear in the transverse sections as large circular openings, varying ordinarily in these 
young specimens from ’005 to '007 in diameter. The interior of these canals is frequently 
occupied by a slender column of pure coal, as in fig. 4, c'. The longitudinal section 
(fig. 2) exhibits these canals as running parallel with the long axis of the rachis, and 
having a nearly uniform diameter throughout their entire length. I have not been able 
B 2 
