very rare exceptions, broke in a plane parallel to the long¬ 
est axis and approximately at right angles to the shortest 
axis. These planes of weakness would seem to be “bed¬ 
ding planes.” Although the balls are nodular, they are 
not concretions—that is, formed by concentric accretions 
of sediment or crystalline substance. The whole nodule 
is formed at the same time and formed congenerically 
with the fossil it encloses. 
The ball was then broken into smaller fragments 
somewhat smaller than a man’s fist. By means of a lap¬ 
idary’s saw, small blocks containing selected fossilized 
plant structures were cut, and later ground upon a re¬ 
volving lap with carborundum grit. Serial nitrocellulose 
peels were then made from all desirable materials. More 
than 3500 plant specimens have been preliminarily iden¬ 
tified and from 3 to 40 peels have been prepared from 
each specimen. To date, more than 38000 microscopic 
slides have been made. 
The first stage in the study of this extensive material 
has been concerned with a rapid and cursory survey of 
the flora—cursory in the sense that the histological de¬ 
tails of the forms have not been described or observed 
closely. The microscopic slides represent sixty-two to 
sixty-six species most of which are new. The species are 
broadly defined and the number now recognized is much 
less than the original estimate; for example, there is only 
one Mesoocylon , whereas we had tentatively separated 
four or five. The task before us is, of course, the descrip¬ 
tion of each species in as great detail as material permits, 
with “serial sections” of all essential parts. 
Plan of the Work 
This paper has been written as an introduction to a 
series of contributions concerning the taxonomy, histol¬ 
ogy, and morphology of the significant members of the 
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