Crossotheca is a spore-bearing form-genus defined by 
Zeiller in 1883, (78) and regarded by him to be filicinean. 
Crossotheca became known as the polleniferous member 
of the pteridosperms because a structure referable to 
Crossotheca was found in organic attachment with a frond 
type known to be seed-bearing. Within the past few 
years Crookall (5) has revived a long-standing contro- 
versy over this case, but before I discuss the issue it 
would be well to give a description of a typical species 
of Crossotheca for which the sterile form is also known. 
Sellards (73) has described the attachment of Crosso- 
theca sagittata (Lesquereux). The detached fructifica- 
tion had been named Sorocladus sagittatus by Lesque- 
reux (11). For the sterile frond, Sellards cites the name 
Pecopteris fontainei Lesquereux MS., which was pub- 
lished without valid description by Lesley (10). 
The small sagittate “‘sporophylls’’ bear 12 free, pen- 
dulous sporangia. These rather large sporangia have a 
length of 3-5 mm. and a width of 0.5—0.75 mm. 
There are probably 128 spores to the sporangium (the 
lowest count in twenty-five well-preserved sporangia was 
46, the largest 106). The spores are large, spherical bodies 
with a diameter ranging from 0.050—0.060 mm. All bear 
the typical tri-radiate scar, which in itself is not allowable 
as evidence in determining relationship. Sellards (73 
states that the thick exospore is marked by minute warty 
thickenings. The spores in our preparations are almost 
smooth. Maceration methods used by Sellards may have 
slightly roughened (swelled) the exine, but this is not to 
be interpreted as a difference in opinion. 
Crossotheca sagittata is borne on foliage of the Pecop- 
teris type, long regarded to be true-fern. Pecopteris fon- 
tainei, the sterile form, belongs to the miltont-abbreviata 
group, which finds a curious paradox in its known frue- 
tifications. The usual fertile form is 4 sterotheca, a typical 
[ 163 ] 
