FOSSIL PLANTS. 
451 
57 t 
Halonia tuberculata ? Brgt. 
PI. xxix, fig 1. 
Stem about three inches broad, flattened by compression to 
one inch, bearing large, round, elevated tubercles, hollow in 
the middle, or funnel-shaped, with a round convex point or 
small mammilla in the center. The specimen is not only 
decorticated, but corroded by sulphuric acid, and nothing is 
seen of the cicatrices between the tubercles but irregular, un¬ 
dulate wrinkles, crossing each other without any definite di¬ 
rection. The hollow tubercles look like large cicatrices of 
Stigmaria. 
As the tubercles of the species of Ilalonia have never been described hol- 
loiv in the center, our plant is doubtfully referred to it. The deterioration of 
the surface has evidently not produced the cavities of the tubercles, for the in¬ 
ternal surface is smooth, regularly inclined downwards, bearing at the bottom 
a discernible vascular scar, similar to that of a Stigmaria. This species may 
be a Stigmaria , though the cicatrices are at least double of those of S. unibo- 
nata, Lesqx. 
From the Chester group, Pope county. 
Genus STIGMARIA, Brgt. 
Ill. Geol. Rep., vol. ii, p. 447. 
Stigmaria elliptica, Sp. nov. 
PL xxix, fig. 2. 
Stem thick, half a foot broad, flattened to one inch; cica¬ 
trices placed in regular spiral quaternate order, elliptical, more 
or less elongated and proportionally narrow, with a central 
nearly round, small mammilla, marked in the middle by a 
vascular point. The specimen is covered with a thin coat of 
coaly matter, which has filled the scars, where it has an in¬ 
creased thickness, obliterating generally the mammillae. These 
