OF THE BRITISH COAL MEASURES. 69 
imperfectly, in a section (S. 237) of specimen 2 * (PI. 1. Phot. 3). This is a 
large stem, quite 15 mm. in diameter when complete. Though the internal 
tissues are so admirably preserved, the cortex, as usual, is in a fragmentary 
state. 
A pair of bundles is very beautifully shown just separating from the stele 
(Pl. 1. Phot. 3, T. 1; cf. Phot. 5). Far out in the pericycle is another pair 
(T. 2) very widely separated, the interval between the strands being nearly 
4 mm. These bundles show some signs of division. What chiefly interests 
us is the presence of an evident, though badly preserved leaf-base, pro- 
jecting far out from the stem and beginning to be marked off at the sides 
by internal bands of sclerenchyma (Phots. 3 & 4). The whole is much 
damaged, but in the middle part the continuity of the tissues is preserved. 
The tangential width of the leaf-base is about 7:5 mm. Towards one side 
of the leaf-base and in its inner part is a distinct pair of bundles ; the two 
strands are about 200 p apart and separated by ground-tissue. In a corre- 
sponding position on the opposite side are the remains of another pair ; one 
of these strands is fairly preserved, the other partly destroyed (Phot. 4, v.b.). 
The leaf-base, so far as preserved, shows the usual Heterangium structure, 
with a rather narrow hypoderma and large plates of sclereides in the ground- 
tissue. This specimen proves that four bundles, in two pairs, entered the 
leaf-base, and thus confirms the evidence of the detached petiole associated 
with specimen 3. 
It may be mentioned that in the section W. 1302, which appears to have been 
cut just below S. 237, two pairs of bundles are shown in the cortex which are 
probably the same as those which pass out into the leaf-base just described. 
Both pairs are shown in Williamson's fig. 1 (1887) (one pair is marked v’, u’; 
the other, not specially lettered, lies on and below the line p). The bundles 
shown in Williamson's fig. 8, on a larger scale, appear to be the former pair. 
The main points in the course of the leaf-traces are now clear, but it may 
be well to summarise the evidence from the remaining sections. 
The transverse sections of specimen 2 are not in a series, but appear to run 
in pairsf. The sections R. 654 and W. 1303 come next each other, the 
former being below the latter. In R. 654 two traces are shown ; the inner 
is the pair just leaving the stele, shown in Phot. 5. The phase is almost the 
same as that of the corresponding pair in S. 237 (cf. Phot. 3) ; a betier 
example could not be found. The two bundles of the trace are quite distinct 
as regards their primary xylem, but close together ; they are separated from 
* This is the magnificent specimen from sections of which most of the figures of 
H. tilieoides in Williamson's memoir of 1887 were drawn. 
S. 237 was cut for me by Mr. F. Chapman from the original block, next to W. 1302 
shown in Williamson's fig. 1 (1887). 
+ W. 1302 and S. 237 have already been dealt with. 
