PLATE 25, 20. 
it. a. a. a. a. parts of the stone remaining, which formed 
the matrix — A fine, light-coloured grit, above the coal. 
I have met with single joints of this fossil in ironstone : 
one in particular of a large size, measuring above twelve 
inches in circumference. 
FIG. 3. 
Represents half of a nodule of ironstone, containing the 
seed-vessel of an unknown plant. 
Since this drawing was made, I have been favoured, 
through the means of a friend, with a much larger, and, 
in many respects, more interesting fossil of the same kind; 
a figure and description of which will be found in another 
part of the work — It is unnecessary to add more, in this 
place, respecting the present specimen. 
FIG. 4. 
Is not given as a petrifaction, though generally mistaken 
for one, by the collectors of fossils in Derbyshire — It is part 
of a nodule of ironstone, having a long, cylindric cavity in 
the centre, partially filled with a loose, white, calcareous 
earth. 
There is little doubt of all nodulous ironstones having 
been in a soft or yielding state — In hardening, cavities 
M 
