the tracheids in longitudinal section: the innermost seem 
to be spiral, while those of the next zone (proceeding out- 
wards) are scalariform, and those of the narrow outermost 
zone are pitted. It is of some interest to note that this 
gradation has been observed in the stems of both Corda- 
ites and Mesowylon. 
The individual strobilus, regardless of sex, is corres- 
pondingly simple. A stalk or pedicel (figure 2) bears a 
large number of spirally arranged segments (figure 4) 
which are tetragonal, but somewhat rounded in trans- 
verse section. The stele is solid but medullates (figure 2) 
quickly. A single trace runs out into each segment, both 
fertile and sterile. 
The outermost bracts are very woody (figure 10) and 
these envelop a large number (fifty to ninety, or more) of 
segments (figures 9, 12). The innermost members are 
slender and acicular. 
Occasionally the female strobilus may bear several 
ovules, for example, three (figure 13). We have made 
serial sections of the specimen here illustrated, but the 
degree of preservation does not permit a full analysis of 
the phyllotaxic arrangement of the segments. In those 
strobili which bear only one ovule, the ovule is absolutely 
terminal and all sterile segments are placed spirally be- 
neath it. 
The male strobilus is clearer and more understand- 
able. Each fertile segment normally bears six erect pollen- 
sacs which are filled usually with the partially developed 
pollen-grains. Figure 17 illustrates several clusters of 
pollen-sacs and figure 18 shows, at a greater magnifica- 
tion, masses of pollen from two stamens. The individual 
winged pollen-grains are shown in figures 19 and 20. The 
specimen illustrated in figure 16 shows a single strobilus 
with pollen in the center. In this specimen the walls of 
the sporangia have disappeared except at the periphery 
[6 ] 
