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AMERICAN JOURNAL OF BOTANY 
[Vol. 8 
the accumulation of detailed studies of exceptionally silicified trunks, many 
interesting features and variations of cycadeoid fructification can yet be 
brought to light. 
5. The most remarkable petrified plant of any kind ever recovered is 
no doubt the National Museum specimen found by Dr. Darton on the 
eastern Black Hills "rim," and illustrated by some ten plates in volume II 
of American Fossil Cycads as Cycadeoidea Dartoni. The type consists in 
the upper half of a columnar trunk perhaps a meter tall, with a finely 
conserved terminal bud. The armor is literally packed with hundreds 
of mature cones, with the dicotyledonous seeds conserved in great numbers. 
There are very few old or aborted axes of any kind, and, while near the 
summit there are a few smaller and perchance younger fruits, the great 
series is uniformly mature. Some further sections from about the apex 
remain to be made. But it is to be cited that the old leaf bases appear 
desiccated or shrunken, while ample sections show no trace of a succeeding 
foliar crown; though a fine crown of young fronds surmounts a scattered 
growth of flower buds in the very different species Cycadeoidea ingens — 
a great type of six hundred pounds' weight from the Piedmont-Black Hawk 
locality some twenty miles due north of the point where the C. Dartoyii 
was found. Yet other species could here be cited. 
In view, then, of comparable species with the full series of lateral axial 
fruits immature, as in C. Masseiana and C. Fisherae, and of further types 
with peduncle series, or with isolated fruits, the Cycadeoidea Dartoni appears 
monocarpic. Vegetative growth has apparently ceased in a time of cul- 
minant fructification with the emergence of all the axes the stem can ever 
produce. But it must be admitted that if only a small percentage of the 
apical fruits are found younger or less full grown than the greater lateral 
series, a partial monocarpy or pseudomonocarpy is indicated. Of this 
more, with extension of thin section series. The available series of large 
tandem sections is shown on Plates 46-50 of American Fossil Cycads, 
volume II, so that the reader may somewhat judge for himself. It may 
be added that the tandem sections of C Dartoni, though not at any time 
regarded as complete without continuation to near the crown, traverse the 
trunk from the base of the recovered segment upward for 35 centimeters, 
cutting nearly fifty seed cones. And throughout this long distance a 
series of uniformly mature cones is present, and evidently extends near 
to the trunk summit. In the belt crossed by the sections there is an average 
superficial area of five to six square centimeters to the cone, indicating for 
this upper trunk segment not less than 500 cones with the ripe embryos. 
On the basal segment of the trunk, which was not recovered (and which I 
have twice sought for at the locality on Battle Creek), there were at the 
lowest estimate as many more, or 1,000 in all for the entire stem (Plate XI). 
If a yearly cone production is concealed above, it had become small. 
Among so many cones, imperfectly grown examples are to be expected, 
