346 kidston: the flora of the carboniferous period. 
the two lateral, which are probably glandular organs, are called the 
parichnos. The leaves are lanceolate, short, or long and grass-like, 
with a single nerve. 
The leaf-cushions were probably considerably elevated in the 
living plant, as impressions frequently show them in this state. The 
flattened condition in which they are usually 
found is in all likelihood the result of pressure 
and the collapse through decay of the more 
delicate inner tissue. When the leaf-cushions 
are distant, the cortex between them is in- 
variably ornamented with fine, irregular, 
longitudinal, flexuous lines, as seen on 
Lepidodendron serpentigerum Konig. (Plate 
LL, fig. 2). The sub-cortical surface is 
generally longitudinally striated, and the 
single cicatrice here shown is the scar of the 
vascular bundle. 
The following terms have been applied 
to the various parts of the leaf-cushion and 
scar. Within the cushion is the leaf -scar. Text 
Fig. 1, a, in form generally rhomboidal or 
sub-triangular, and containing the vascular 
scar and the two parichnos ; extending both 
above and below the leaf-scar is a central 
keel which often bears notches on its lower 
part. Immediately above the leaf-scar, in 
the line of the central keel, is a small cica- 
tricule called the ligule scar, c, and just 
beyond it is generally the small triangular 
notch, e. The area surrounding the leaf- 
scar is the " field," d. In most species of 
Lepidodendra immediately below the leaf-scar 
are tw^o oval pits, one on each side of the 
keel ; these are probably glandular organs, /. 
The " field " is generally free from any mark- 
ings, but in Lepidodendron Wortheni Lesqx. 
Fig. 1. — Leaf cushion 
of Lepidodendron 
acid ea turn Sternb., 
slightly enlarged. 
For description 
text. 
see 
Fig. 2. — Lepidodendron 
Wortheni Lx. Leaf 
cushion, showing 
ornamentation. (No. 
2731.) 
