OP THE FOSSIL PLANTS OF TFIE COAL-MEASURES. 
105 
Plate. 
1 
Figiire. 
Page at wliieli 
reference is 
made to the 
figure. 
i 
14 
i 
1 
1 
1 
12 
Transverse section of a still older branch, in which the 
separated portions of the central mass of trachese are 
seen at a, a', whilst the vacant space left by that 
separation is now occupied by a parenchymatous 
medulla, a. X 30. Cabinet number, 1141 . 
92 
i 14 
j 
13 
Outline representation of the central area of a yet older 
branch of Lyginodendron Oldhamium, enlarged to 
little more than one-fourth of the scale of figs. 10, 11, 
and 12 : a, area occupied by the enlarged medulla ; h, 
inner margin of the exogenous xylem ; a, a, six 
clusters of tracheids corresponding to those, a, a , of 
fig. 12 ; a", a”, spaces left by the further separation 
of the bundles rd, cd. X 8. Cabinet number, 1128 
92-96 
14 
1 
i 
14 
Transverse section of a jmung stem or branch of 
Heterangium Grievii: a, large axial mass of barred 
tracheoe, intermingled with vertical rows of paren¬ 
chymatous cells, the whole constituting the vasculo- 
medullary axis of the plant; h, thick parenchyma¬ 
tous cortex; e, peripheral zone of ti’ansversely 
intersected sclerous fibres ; cd, bundle of tracheids 
passing outwards from the vasculo-medullary axis 
to some peripheral appendage. X 19. Cabinet 
number, i915P. 
, 
96 
1—1 
15 
Two small clusters of the tracheae of fig. 14, « : a, 
larger tracheae; h, smaller tracheae, with some 
parenchymatous cells ; c, bands of apparently dis¬ 
organised cellular tissue. X 75. 
96 
14 
1 
16 
Seven cells, further enlarged, of the fibrous zone, e, e, 
of fig. 14. Each cell consists of a thick lignified 
wall, with a well-marked central lumen .... 
96 
15 
17 
Longitudinal section of a stem like fig. 14 : a, vasculo- 
medullary axis; h, l>, inner zone of the cortex; 
h', undulating external boundary of the zone, h ; 
c, outer cortical zone ; c, lenticular and indurated 
clusters of parenchymatous cells ; d, areas occupied 
1 
MDCCCXC.—B. P 
