Igto] BRIEFER ARTICLES 309 
In their more essential characters they agree with the stomata as described 
by ZEILLER for F. Hoheneggeri and by VELENovskyY for F. bohemica. Just 
what were the physiological factors responsible for the great reduction 
of the leaves and the assumption of the photosynthetic processes by the 
branches in Frenelopsis it is difficult to imagine.. Such features are 
usually associated with peculiarities of climate and habitat, and suggest 
strong insolation and lack of humidity; but such conditions are not 
suggested by the other members of the flora associated with Frenelopsis, 
since with the Potomac species are found large numbers of ferns, many 
of them apparently tree ferns with decompound fronds a meter or more 
across, and large numbers of cycads of various genera and large size; 
while in the latest beds in which F. ramosissima occurs there are con- 
siderable numbers of dicotyledonous leaves, some of which are allied 
with genera which in the modern flora are confined to tropical areas 
where the humidity is high and the rainfall heavy. 
It is possible that these peculiar features in the cretaceous species of 
Frenelopsis were inherited from triassic ancestors which acquired them 
during those portions of the Triassic when the climate was extremely 
arid, as we know it was from physical as well as paleontological criteria. 
—Epwarp WILBER Berry, The Johns Hopkins University, Baltimore, 
Md. 
