Dimensions of the fructifications 
Specimen 42159 
maximum diameter 58 mm. 
minimum diameter 49 mm. 
height 47 mm. 
xylem of petiole, breadth 2.2 mm. 
“length” of petiole 8 mm. 
“width” of petiole 4.5 mm. 
Specimen 42635 
56 mm. 
27 mm. 
not determined 
1.8 mm. 
6.5 mm. 
4.2 mm. 
The sporangia vary in length from 1.5 to 1.7 mm., 
and in diameter from 1 to 1.2 mm. Many smaller “diam¬ 
eters” have been measured and recorded, but they are 
invariably from planes which are not median. 
The spores measure 0.05 to 0.065 in diameter and are 
nearly spherical in shape. The tetrad scar is prominent 
though not large. Some spores, especially those viewed 
from the apex or scar end, appear to be slightly triangu¬ 
lar in outline, but this may be due either to preservation 
or immaturity. 
The sporangium is constructed of two layers of cells, 
an outer layer composed of more or less cubical, thick- 
walled cells, enlarged over one side to form an annulus, 
and an inner layer of thin-walled cells, smaller in size than 
those of the outer layer. This inner layer is only occa¬ 
sionally preserved, and since its ontogeny is unknown, it 
is not possible to term it tapetal. The sporangia are 
grouped in numbers varying from three to ten (some¬ 
times even more) attached to short pedicels, which are 
the termini of a much-branched axis. The pedicels are 
provided with a vascular strand composed of several cells 
of scalariform tracheids. The “petioles” which bear the 
pedicels have the characteristic Botryopterid oj-shaped 
stele. 
Comparison with Botryopteris forensis 
It is obvious that the spores of the Iowa species are 
[159] 
