I62 
G. R. WI ELAND 
appears rather primitive as compared with the double strand of the cycads, 
and may have had some relation to microphylly and plasticity of type. 
But the double strand appears in ancient gymnosperms; and, also, in 
Ginkgo the leaf traces arise from the stele as a pair of collateral bundles. 
Nor would it be cause for surprise to find in some small-leaved cycadeoid 
with a thin cortex such a double trace, or even two weak lateral traces. 
Turning to fructification, the contrast between the two types is great 
because of sporophyll emplacement coupled with retention of the primitive 
microsporophyll in one instance and a carpophyll in the other. But the 
cycadeoid microsporophyll was also plastic and reduced in well attested 
instances from both the Triassic and Jurassic rocks. It might, therefore, 
be believed that some members of the original cycadeoid alliance had both 
the mega- and microsporophylls reduced in spiral emplacement. Such, 
however, would lead toward Gnetalean or coniferous types, and what 
appears to have been an instance will presently be cited. It may be added 
that the observation that the Cycadeoidea microsporophyll was as dis- 
tinctly horned or bicornute as that of the Mexican Ceratozamia, and freely 
tomentose, brings the groups together a bit, and at the same time suggests 
possible form variation toward conifers. 
The Seed Ferns 
Derivation of the Cycadophyta in totality from ferns is in accord with 
the views held by botanists throughout all the studies of existent and fossil 
plants for the past two or three score years. This is a section of botanical 
science to which its votaries may point with confidence if not with pride; 
and further discoveries are awaited with the certainty that they will be 
made. The seed fern Lyginopteris was fully hypothesized before its final 
discovery. But adequately to treat this antecedent relationship would 
require an attention to structural details beyond the limits of the present 
discussion. It is safe to say that both the vegetative and the reproductive 
hiatus between the quasi-ferns and the early cycadeoids is bridged by known 
structures, found isolated to , be sure, though conclusive. One of my 
colleagues has also given consideration to this fundamental relationship. 
The Cordait6s and Dolerophyllum 
The origin of the Cordaiteans is so lost in geologic antiquity that an 
otherwise rather striking affinity is more or less obscured. It must be 
remembered, too, that in going back so far toward the beginnings of these 
plants with seeds often of enormous size, the likenesses must frequently be 
the merest of parallelisms. Could sessions like ours have been held about 
the close of the Devonian, when Callixylon Oweni flourished where we now 
stand, it may well be imagined that discussion would have turned on 
whether the Cordaites seed was phyletically related to the synchronous 
ancestral cycadeoid seed or not. 
