PLATE 19, 20. 
The cliaracteristic distinctions of the species are frequently 
attainable, if studiously sought after, by a diligent and 
careful comparison of various specimens; and the habit 
or general appearance of the fossil otten leads to the know- 
ledge of the natural class and order of the recent plant : 
but its genus, for the most part, remains undetermined, 
or doubtful. 
Fig. 4'. Part of a nodule of ironstone, broken (in regard 
to its contents) in a transverse direction, showing three 
whorls of leaves belonging to the above described petri- 
faction. Similar remains have been called petrified Jhwen 
by collectors of fossils. These difter, however, from the 
next specimen, only in size, in being found three or tour 
together in the same nodule, and in the direction in which 
they lie in the stone. 
5. A nodule holding a single plant in a different direc- 
tion. 
6. I am not certain if the remains in this nodule are the 
same as those above. The stem is much thicker, and the 
whorls more distant, in proportion to the size of the plant, 
than in most other specimens I have examined. There is 
also some appearance of branches in one part of the stem ; 
but I have not, as yet, met with any specimens that would 
enable me to determine a specific distinction. 
