338 The American Geologist. June, 1895 
has appeared in the American Naturalist.* In view of the 
extraordinary character of the fossils, a review of the papers 
will be of interest. 
The typical species of the genus is described as possessing 
an oblicjuely ascending rhizome-like portion, varying from 8 
to 18 inches in diameter and from 5 to 8 feet in length. The 
free extremity is generally broken off and is more or less 
friable, but from the opposite end there arises an axis, or 
perpendicular stem, around which is a regular stone coil. (PI. 
XI, Fig. 1.) On the opposite side to that from which the axis 
and coil arise is frequently a short projection, seldom more 
than 10 or 15 inches long. This part, taken in connection 
with the coil and the long projection at the other end, has 
given rise to the common name corkscrew, which it most 
strikingly resembles. The coil twines to the right in some 
instances and to the left in others, the two at times being in 
close juxtaposition in the beds. In other examples the coil is 
more or less double; it may be carinated, or it may even lack 
the central axis around which to coil. These are all variations 
of the same general structure and have been given specific 
names by Prof. Barbour. 
The outer surface of the fossils is a "tangle of ramifying, 
intertwining tubules, varying in diameter from /^ to ^ of an 
inch. Some are a full fourth of an inch, although the average 
is about 3I2 of an inch." The tubules are more densely clus- 
tered toward the center of the fossil, until a solid, white com- 
pact wall is reached, which encloses a central core of rock, 
irregularly traversed longitudinally by large tubules, and 
transversely by minute ones. 
Examination of these tubules shows a cellular structure 
very plant-like in character. A longitudinal section (PI. XI, 
Fig. 2r/) shows the cells to be elongated and piled one on top 
of the other like the cells of palisade tissue of a living leaf. 
A cross section (PI. XI. Fig. 26) shows a series of irregularly 
polygonal cells, arranged at times about a central space. 
The locality in which these fossils occur is in the extreme 
northwestern corner of Nebraska in the neighborhood of 
Harrison, Sioux county, on the Fremont, Elkhornand Missouri 
Valley R. R. It is in the midst of the so-called Bad lands, 
*In tlie region of tlie new fossil, Dwrnonelix. Amer. Nat., vol. xxix, 
pp. 21:5-227, March, 1805. 
