170 
G. R. WI ELAND 
Then Thompson goes on to say that the negating cycadeoid features are the 
cycadean habit and leaves, motile spermatozoids (!), the primitive gymno- 
sperm condition, and absence of angiosperm adumbration in the gametes, 
endosperm, or embryo. Thompson as a botanist pays even less attention 
to chronology in his assemblage of characters than does Berry as a paleo- 
botanist. A cycadeous habit for Williamsoniella or Wielandiella! Never, 
if the thought is only of gnetaleans! And, of course, if fossil foliage is to 
be excluded from the reckoning, what should be done with Tumboa? Leaf 
variation is not a special feature of gnetaleans. Besides, as they still 
persist, they probably changed late or more or less inadaptively, and too 
slow to be ancestral to anything. 
Those wishing to examine the gnetaleans from the critical phylogenetic 
point of view should begin with the work of Lignier and Tison. It is 
briefly excerpted and commented on in my "American Fossil Cycads," 
volume 2, pages 235-237. In their summary of the features of the hypo- 
thetic Gnetaloid precursor of the angiosperms may be discerned a funda- 
mental type which could not have been remote from some of the contem- 
poraneous cycadeoids. The great question remains, at what period did 
the main separation actually begin? When this becomes even approxi- 
mately known, intensive search may be made for the fossil evidence and 
field relations. 
If allowed a subscription of faith, if permitted a prediction, then I 
make mine that future work will develop the fact that plant evolution 
has followed an orderly sequence and course. Its current has been as sure, 
as steady, as that of the majestic river by the banks of which we stand. 
From age to age the great groups have come down side by side, some 
specializing certain features a little more, others holding to more generalized 
structures, or losing apparent relationships because of reductions, but all 
undergoing that endless change from which neither genus nor species 
has ever been exempt. Almost no forms, scarcely a family, need be re- 
garded as more ancient or more modern than any other. 
Huxley, with his keen insight, noted as a most astonishing thing the 
fact that, taking all animal life, the proportion of extinct ordinal types is 
so exceedingly small. In the 125 orders of animals only about ten percent, 
perhaps now fifteen percent, appeared wholly extinct. But with all the 
advances made in paleozoology revealing complexity of form, there has 
been much of simplification, and type after type has been found much 
older than at first thought. 
The plant record is, so far as the higher types are concerned, both older 
and more fragmentary than is much of the animal record. Its study has 
been late in development, and has often lagged. The results from the dif- 
ferent continents are as yet poorly coordinated. Nevertheless the broader 
outlines of ancient vegetation already appear. The known gymnosperms 
and the pseudo-gymnosperms or cycadeoids go back to the Paleozoic, 
