OF THE FOSSIL PLANTS OF THE COAL-MEASHRES. 
97 
line the cortex, c, cl, assumes a very difterent aspect. Its cells still arrange themselves in 
vertical but undulating lines of a peculiar character. At the points c , c', we find trans¬ 
versely disposed bands of very strongly defined cells, alternating with intermediate 
areas, cl, cl, through which the same lines of cells continue their vertical course but with 
altered flexures. The cells themselves, also within these areas, have very much thinner 
walls. The cell-clusters, c, c', as seen in these vertical sections, are parts of numerous 
masses of more or less definite lenticular form, which abound in this part of the cortex ; 
on making broad tangential sections through the same we note that, whilst many of 
these masses are arranged in horizontal transverse lines, many of them incline at very 
various oblique angles. Fig. 18 represents a small portion of a very superficial 
tangential section, in which c is the part of the cortex under consideration, and e, e, 
the fibrous investing layer. The section of one of the lenticular clusters of cells c 
illustrates the peculiar symmetrical arrangement so frequently observable within these 
clusters. The longitudinal section, fig. 17, shows that at their inner margins these 
lenticular cell-masses compress the inner cortex h, those margins projecting into the 
concave flexures of the line h'. Similar clusters to those seen at fig. 18, c, in the 
transverse sections of these stems. The sclerous cells of the zone e of fig. 14 are seen in 
figs. 17 and 18 to be narrow fibres of very great length in proportion to their diameters. 
This zone cannot fail to remind the histologist familiar with the structures of the 
rhizomes of recent Ferns of the very similar hypodermal layer seen in some species of 
Nephrolepis. 
The true affinities of this plant are as yet undetermined, but I have strong con¬ 
viction that it will be eventually proved to be a true Fern. 
Bowmanites. 
In volume .5 of the third series of the Transactions of the Literary and Philosophical 
Society of Manchester, I published, in 1871, a description of a fruit to which I gave 
the name of Volkmannici Dawsoni, and further illustrations of the same fruit were 
given in my Memoir, Part V., of this series.* At that date the verticillate-leaved 
plants of the Coal Measures were ill understood, and much confusion has resulted from 
that imperfect knowledge; a confusion which a few words of explanation may help 
to remove. 
Paloeobotanists have for more than a century been familiar with the existence, in 
the Carboniferous strata, of a number of plants, the leaves of which were arranged in 
verticils. In his ‘ Prodrome,’ published in 1828, Brongniart threw a considerable 
number of these plants into two groups to which he gave the generic names ot 
SplienophyUiim and Asterophyllites. The former genus he defined, among other 
characters, as “ feuilles verticillees, au nombre de six a douze, distinctes jusqu’a leur 
* ‘ Phil. Trans.,’ 1874, p. 54, Plate 5, fig.s. 28-30. 
MDCCCXC.—B. 
O 
