DISTRIBUTION AND RELATIONSHIPS OF THE CYCADEOIDS l6l 
our views of the relationships of the cycadeoids, and in assembhng the 
broader known facts and passing on to some quite legitimate inferences, the 
present object is of course to bring into view mainly those features which 
have a bearing on the phylogeny of seed plants in general. In the glimpse 
just had of distribution, attention was mainly fixed on relationships within 
the Cycadophytes. It was found that no headway could be made in pictur- 
ing the real extent of cycadeous vegetation in the Mesozoic, without some 
consideration of the hypothetic variation within the group. And that 
subject could have been pursued much further. Now it is the aim to single 
out analogies without the group. Being essentially gymnosperms, it will 
be contended that the cycadeoids relate themselves to the other spermato- 
phytes in the following order of closeness: firstly to the cycads, secondly 
to the seed-bearing quasi-ferns, thirdly to the Cordaites and Dolerophyllum, 
fourthly to the Ginkgophytes, fifthly to Araucaria, sixthly to the Abietineans, 
seventhly to the magnolias and other dicotyls, and eighthly to the Gnetales. 
This order may be conveniently followed in discussion. 
The Cycads 
There has been a wide divergence of opinion as to whether the cycadeoids 
are in any near sense related to the cycads at all. But as knowledge of the 
existent and extinct groups has been extended, and as better defined terms 
have been reached, the difference of opinion or of viewpoint is lessened. So 
distinctly is this true that it would hardly be fair to name any one, either 
in this country or in Europe, as holding unqualified views. One might 
say that the likenesses between the two groups are distinct and the differ- 
ences striking, or the reverse. And this alternative or disposition of some 
to lay stress on vegetative features in this classification, and of others to 
emphasize fructification, has found expression in the division of the super- 
group Cycadophyta into the Cycadales and the Hemicycadales or half- 
cycads. Certainly no one would deny that the cycads and cycadeoids 
are the two most contiguous of the greater gymnosperm phyla. The two 
groups must have come from the same section of the Carboniferous plant 
alignment. Throughout all of Permian and Triassic time they must have 
been in close histologic contact, and by lower Jurassic time about all the 
visible difference in the wood was the preponderance of scalariform wood 
in the cycadeoids in contrast to the pitted wood of the present-day cycads. 
Both wood types occur in both groups, and histologists are welcome to think 
as they please about which is the more primitive. Of course, while insisting 
upon points of vegetative resemblance it is the large pith and thin woody 
cylinder of the petrified stems, or the family Cycadeoideae, which is cited. 
But the fact cannot be too strongly emphasized that such stems are of 
unusual type. They are the only ones definitely known amongst the cycads. 
It was seen, however, that the characteristic and plastic cycadeoids were 
no doubt small-stemmed and microphyllous. The single strand leaf trace 
