388 
almost as hard as burnt brick.” It was in this clayey material 
that these plant-stems were found. 4 
The stems are very abundant and scattered in all directions 
through the mass, They appear to have been much rolled about 
and broken up, it being difficult to find a piece three centimetres 
in length. They were originally hollow, but most of ae are 
now pressed perfectly flat, although an occasional one is found 
that was filled with clay when probably in a fresh state and conse- 
quently retains nearly its cylindrical form. When liberated by 
the crumbling of the sandy clay, the stems are very dark brown, 
almost black, in color and perfectly opaque. By boiling them for 
a few moments in dilute acid, a large part of the coloring matter 
was discharged and the cellular structure could then be made out. 
Fig. 1.—Epidermis of Paleohillia Arkansana X< go. 
a, a, bands of long, narrow cells. a 
b, b, bands of short irregular cells, with three longitudinal © 
stomata, 4 
¢, c, stou ata with four and six guardian cells respectively. 
Fig. 2.—Stoma with four guardian cells X 300. 
Fig. 3.—Stoma with five guardian cells xX 300. 
