FOSSIL PLANTS. 349 
of superposition, to rebuild the vegetable in its original position. 
At Carbondale, in Pennsylvania, a true forest of Calamites has 
been crossed in the opening of an inclined tunnel through a bank 
of sandstone to a bed of coal underlying it. The fragments of 
petrified stems taken out of this passage are in such abundance 
that they have been used for the construction of a kind of gang- 
way for running the coal cars out of the mines. These fragments, 
nearly without exception, are mere disks, varying in length from 
one to four inches, without relation to the size or diameter of the 
stems, which measure from three to six inches; the differences in 
the length of the sections being as marked for the large as for the 
small stems. All these fragments represent only as far, at least, 
as I could determine from the examination of hundreds of speci- 
mens, two species of Calamites, O. Suckowii and O. approxima- 
tus Brgt. The walls of the tunnel are adorned by a number of 
these trees, still in their standing position and half imbedded in 
the sandstone. hough these stems are continuous, they show, 
at various and irregular distances, horizontal fractures where they 
break or are dislocated at their separation from the surrounding 
sandstone. Some of these trunks of Calamites, which in their 
natural state were evidently hollow, have been abruptly folded or 
crushed, like hollow cylinders in bending under their own weight, 
or by some external force; but even at the point of inclination or 
tortion of these stems, the fracture is horizontal or perpendicular 
to their erect position. At Paintsville, Johnson county, Ken- 
tucky, the bottom of the river, which at some places has been 
cleanly washed, is marked, as in a kind of irregular mosaic work, 
by the broken tops of large trunks of Sigillaria, still in their 
original standing position, all EAOa fractured. One of these 
trunks measures twenty-two inches in diameter. The same pecu- 
liar kind of horizontal pera is generally observable on the 
silicified trunks so abundantly found in some parts of Southern 
Ohio, especially in the bed of Shade river, near Athens. They 
are, most of them, pieces of stems of fern trees (Psaronius), vary- 
ing in diameter from three to twelve inches, broken in disks from ` 
two to fourteen inches long. A few of these pieces of silicified 
wood are irregularly broken and disfigured on the outside by mac- 
eration; but generally they preserve their cylindrical form, and 
when of some length show here and there, at various distances, 
horizontal splits, uninterrupted all around the trunk, where a dis- 
