FOSSIL PLANTS. 
425 
Genus EQUISETITES, Sternb., Vers, ii, pi. 43 
Stem fistulose, cylindrical, striate lengthwise, articulate, simple or branching 
at the sheathing articulation, sheaths attached under the articulations, erect, 
dentate. 
Equisetites occidentalis, Sp. nov. 
PL xx, fig. 5. 
We have only one sheath of this species, the first trace of a 
true Equisetites found in the Coal Measures of this continent. 
The sheath is open or unfolded, somewhat broken in the mid¬ 
dle, about three inches across, two inches long, regularly divi¬ 
ded to about the middle by lanceolate, obtusely pointed teeth, 
marked by a strong nerve, which descends from the point of 
the teeth to the base of the sheath. The surface in the mid¬ 
dle and between these nerves is irregularly wrinkled, and the 
base, in the line of connection with the stem, is marked by 
regular, half round notches, corresponding evidently with the 
striae of the stem. 
The specimen is from Mazon creek, a concretion where this part of the plant 
is distinctly preserved. Another specimen from the same locality, but in a 
bad state of preservation, contains also fragments of an Equisetites , whose spe¬ 
cific relation cannot be recognized. It has the remains of a stem about one 
inch in diameter, with a lacerate sheath. 
—54 
