156 
G. R. WI ELAND 
for the view that the fertile dichotomizing branch ends, all thus far found, 
are anything else than the broken-off branches of trees. Just such branches 
of conifers of like or of older age are found. The chances that these forms 
had either structures or a habitus in any way indicating procumbency, are 
exceedingly small. In groups or in forests they might have had some like- 
ness to screw poines of mountainous rather than of tropic rain forest dis- 
tricts. The peculiar Pandanus forest of the Lokon of the Celebes is here 
suggested. But the point to note first is, that there is the fullest reason to 
believe that the small Taeniopteroid leaves of the small-flowered cycadeoids 
are related to innumerable megaphyllous types of truly tropic habitat, only 
the latter would be less plastic forest elements. 
Whether this view of relative aplasticity for these megaphylls is right 
or wrong, they soon undergo extinction, after in their prime vividly recalling 
in both habitat and habitus the earlier coal-swamp floras. Neither William- 
soniella nor Wielandiella taken by itself indicates tropic plants at all. 
They were probably tropophylls or plants which shed their leaves with the 
seasons. The stems are usually found bare, the attachment of the dis- 
sociated leaves being determined only with difficulty. These are in a word 
generalized plants which so far as habitus goes might well grow in temperate 
to cool climates. Until far more is learned about them they should at least 
be held valueless as indices of tropic climates. But as the small-stemmed 
cycadeoids were related to the contemporaneous Ginkgos, and at the same 
time to early angiosperms, the inference becomes direct that either they or 
their close relatives already had the capacity to live in every clime. 
There is also a suspicion that study of the associated ferns may compel 
revision of the long-accepted view of the universality of tropic climates 
throughout the Mesozoic. A. G. Nathorst, the most eminent living student 
of fossil plants, says of these suggestions in a letter just received: "I think 
you are quite right that during the time when the Ginkgophytes and Cycado- 
phytes dominated, many of them must have adapted themselves for living 
in cold climates also. Of this I have not the least doubt. Remember, for 
instance, Juniperus communis. If Juniperus were extinct, and conclusions 
were drawn from all the other species found fossil in the parallels where 
they now live, it would be believed that the whole genus was bound to 
live only in the temperate climates. Yet Juniperus communis thrives well 
in Greenland." 
Since current opinions of Mesozoic climates as based on plants are so 
open to challenge, any details which can possibly be learned about the 
cycadeoid distribution have a doubly important bearing on phylogeny. But 
it must be freely admitted that the subject can only be approached slowly, 
and is here considered superficially. 
In a fossil form distribution is, to use a long and emphatic word, bi- 
dimensional. Distribution in a living form is simply lateral; but in fossils 
it is both lateral and vertical with more or less uncertainty at all limits. 
