OF THE FOSSIL PLANTS OF THE COAL-MEASURES. 
103 
Index to the Plates. 
Plate. 
Figure. 
Page at whicli 
reference is 
made to the 
figure. 
12 
1 
Part of a transverse section of a stem or branch of 
Lyginodendron Oldhamium: a, medulla; h, exo¬ 
genous tracheseal zone; c, position occupied by the 
middle cortex, not preserved in this specimen ; d, pair 
of vascular bundles; e, outermost cortex; f, radial 
zones of parenchyma, alternating with the zones of 
sclerous fibres, g ; h, h, portions of peripheral emer¬ 
gences, corresponding to those at fig. 6, li, h ; i, i, 
transverse section of a petiolar organ identical with 
Rachiopteris aspera, Will., with its pair of vascular 
bundles at k. X 13. Cabinet number of the 
original specimen, 1880 . 
89-90 
13 
2 
Transverse section of a slightly crushed petiole, 
Rachiopteris aspera, Will.: c, inner cortex; e, e, 
outer cortex composed of radial bands of sclerous 
prosenchyma, partially separated by thin zones of 
parenchyma; k, k, twin vascular bundles, identical 
with k, k of fig. 1 ; 1, gum-canals. X 250. Cabinet 
number, 1854 . 
90 
13 
2a 
One of the intercellular gum-canals of fig. 2, /, further 
enlarged . . 
90 
13 
3 
Part of a transverse section of a stem of Lyginodendron, 
in which the inner cortex, c, is preserved; the 
reference letters, a to g, as in fig. 1. But at 6', h' 
is a development of trachemal laminae growing 
centripetally into the medulla ; at h" is one of the 
large multicellular medullary rays referred to at 
p. 95 ; li, base of a peripheral emergence. X 20. 
Cabinet number, 1138 . 
90 
12 
4, 5 
Three of the gum-canals of the middle cortex, c, of 
fig. 3, further enlarged ; c, c, cortical cells. Each 
lined with a thin layer of carbon at a, enclosing a 
1 
1 
cylindrical rod of the same at 6. X 250 . 
90 
