Pee Sid 
70 DR. D. H. SCOTT ON THE HETERANGIUMS 
the metaxylem of the stele by a few layers of conjunctive parenchyma, in 
which some tangential divisions have taken place. The secondary wood 
proper to the double leaf-trace is still continuous, but the ares corresponding 
to the two bundles are already evident. Most of the phloem is perfectly 
preserved ; it about equals the secondary xylem in thickness. 
In the outer part of the pericycle there is a second trace; the two strands 
are wide apart (about 4 mm.) and each is preparing to divide. In the next 
section (W. 1303) the inner trace has moved out into the pericycle ; the two 
strands are now diverging, each has its own are of secondary wood and bast. 
These bundles were admirably figured by Williamson (fig. 5, 1887) at a time 
when their leaf-trace nature had not yet been recognised. The outer trace 
is here in the cortex, but only fragments are preserved. 
The two sections W. 1619 and Q. 55 are similar and must have been eut 
near together, but I cannot exactly correlate them. In W. 1619 no leaf- 
trace is starting from the stele—the appendage shown is no doubt an adven- 
titious root (figured by Williamson, fig. 13, 1887). "Two double bundles are 
seen in the cortex, just beyond the pericycle. They are about 6 mm. apart, 
but may have been displaced ; they probably belong to the same trace. 
Q. 55 shows two leaf-traces. The inner is in the perieycle—one strand has 
been displaced. These bundles have almost lost their ares of secondary 
wood, and are therefore at a more advanced phase than those deseribed in 
W. 1303. The other trace is represented by a double bundle in the cortex 
the eompanion pair is no doubt lost, for much of the cortex is destroyed, 
Of specimen 1, I only know of two sections, one in the Williamson and 
one in the Manchester Collection (W. 1301 and R. 632). Both are trans- 
verse and cut close together, R. 632 being just above W. 1301. The specimen 
is exceptional as regards preservation, for the cortex is fairly preserved, 
while the pericycle is almost destroyed. W. 1301 shows three leaf-traces 
and a leaf-base. The innermost (Trace 1) consists of a pair of strands, 
separated by some conjunctive tissue, about to depart from the stele. A pair 
of widely diverging bundles (Trace 2) is seen in the pericycle, and a damaged 
one (Trace 3) in the cortex. The leaf-base or petiole in connection with the 
stem was described in the joint memoir by Williamson and myself (1895, 
p. 763). Only one bundle is shown, but, as the section of the petiole is 
longitudinal, this proves nothing as to the total number present. The 
conjecture as to fusion of bundles was certainly wrong, as shown by the 
evidence from specimens already described (p. 68). 
The other section, R. 632 (Phot. 2), shows the same leaf-traves. Trace 1 
has searcely moved. The two strands, though only just separating from the 
wood of the stele, are about 370 p apart, showing clearly that the bundles are 
distinct at their origin. Of trace 2 only one bundle is preserved ; it lies on 
the border of pericycle and cortex, and is dividing. Trace 3 is in the inner 
