1921] COULTER & LAND—LEPIDOSTROBUS 107 
from the same strobilus, the tip being the only part missing. The 
restored strobilus was 22 cm. long and 5 cm. in diameter at the 
base. The structures were well preserved, with the exception of 
the axis, which is replaced by calcite and pyrites. The strobilus 
is mature; the sporangia have all opened and are empty excepting 
here and there a few spores. Enough sections were made to show. 
its character, from the base to the broken tip, the general condi- 
tion of the strobilus being almost exactly identical with that 
of the fragment described by CouLrer and Lanp. There is no 
appreciable difference in size of any of the spores, both those in the 
basal sporangia and in the sporangia near the apex averaging 27 in 
diameter. It seems probable, therefore, that this particular species 
of Lepidostrobus is homosporous, although it is possible that the 
spores found in the basal sporangia entered through the dehiscence 
slits. It would seem almost impossible that, in such a well 
preserved and compact strobilus, all of the megaspores, if there 
were any, could have escaped. The real solution of the problem 
lies in the finding of younger strobili which have not yet shed any 
spores. Negative evidence, however probable, is never conclusive; 
but the evidence in the present case is so strong that it seems safe 
to infer that this species of Lepidostrobus is homosporous. 
The form genus Lepidostrobus was originally established to 
include all of the strobili of Lepidodendron. Later it was found 
that all such strobili could not be included, even in a form genus, 
so that “true” Lepidostrobus is restricted to those strobili of 
Lepidodendron characterized by “the great radial elongation of 
the sporangium, and its attachment by a long and narrow inser- 
tion to the upper surface of the sporophyll-pedicel throughout its 
length.”* The chief interest in connection with these strobili is 
the question of heterospory. If heterospory has been attained by 
all these forms, the origin of the homosporous Lycopodiales is 
left in the region of the unknown. Certain species of Lepidostro- 
bus are known to be heterosporous, and all of them are suspected. 
In one well preserved specimen the microsporangia occur in the 
upper part of the strobilus and the megasporangia in the lower part, 
as in certain species of Selaginella. The inference has been that 
4Scort, D. H., Studies in fossil botany. London. 1909. 
