STIGMARIA. 133 
When broken transversely, a small cylindrical axis is seen 
to extend in a longitudinal direction through the stem, like 
a medullary column ; it seldom occupies the centre, but lies 
near to one side, and parailel with a depression on the outer 
surface of the fossil. This internal body is often loose, and 
removable ; its surface is covered with interrupted, irregular, 
longitudinal, ridges, which leave corresponding depressions 
Lien. 36. STIGMARIA FICOIDES. 
Carboniferous. Derbyshire.—i nat. 
Fig. 1.—Portion of a stem, with some of the rootlets (formerly considered 
as leaves) extending into the surrounding clay. The internal 
axis is seen at a@; and the corresponding groove on the portion 
of external surface that remains. 
2.—An outline of one of the rootlets, with a tubercle to show the 
mode of its attachment by a ball and socket joint to the root. 
on the walls of the cavity in which it was inclosed. Lign. 36, 
represents a fragment exhibiting the characters above de- 
scribed. 
