160 BOTANICAL GAZETTE | SEPTEMBER 
nize, however, that the structures usually preserved are not the 
most convincing as to relationships, and that nowhere are appear- 
ances more deceitful. While we have no sympathy with wild 
generalizations based upon fragmentary material, there is an 
increasing accumulation of data which furnish a substantial 
foundation for some conclusions. It seems to be clear that dur- 
ing the Paleozoic there was an increasing display of gymno- 
sperms. The fragments which bear this testimony became very 
abundant in the later periods of the Paleozoic, and are regarded, 
for the most part, as Cordaites. Associated with these forms is 
the great display of Marattia and its allies. A distinct type of 
leaf and of stem is attributed to each of these great groups, 
and when seeds or sporangia are associated with them the case 
seems clear enough, but apart from such association the uncer- 
tainty is profound. Intergrading forms between the two are to 
be expected, but with material so fragmentary and non-commit- 
tal it would be a rare chance that would lead to its definite 
demonstration. In the Coal Measures the cycad type becomes 
apparent, but not prominent. This would seem to indicate either 
an early differentiation from the Cordaites plexus, or a late dif- 
ferentiation from the Marattia plexus. I see no difficulty in the 
former view, as I see no advantage in multiplying the independ- 
ent heterosporous and seed lines until forced to do so by incon- 
trovertible evidence. The domination of cycads during the 
Mesozoic, and their subsequent decline are well-known facts. 
More suggestive, however, is the history of the conifers. It 
is generally stated that this line, in its modern expression, began 
during the Paleozoic, and that our modern genera have been 
recognized by stem and leaf anatomy. Such methods of deter- 
mination we know to be untrustworthy, as there is the greatest 
possible amount of anatomical diversity even in contiguous 
regions of the same organ, much more in different orgams and 
at different ages. In examining the claim that modern conif- 
erous genera appeared during the Coal Measures, I find no evlr 
dence that seems to be worthy of serious consideration except 
ing that with reference to Ginkgo, and it is an interesting 
