508 Bower.—Studies in the Phylogeny of the Filicales. 
example, the leaf of P, Hillii shown in Fig. 6 might be very nearly matched 
by the more complex leaves of Cheiropleuria ; at the same time it is impos¬ 
sible to miss the resemblance which they also show to so distant a type as 
Ophioglossum palmatum (compare Land-Flora, Fig. 238, p. 436). It is also 
to be noted that the leaves, both of Platycerium and of Cheiropleuria and 
of Dipteris , show the ‘ Venatio Anaxeti Accordingly, a comparison of the 
vascular system of their shoots should present points of interest. 
Miss Allison has lately described the vascular system in the rhizome 
of certain species of Platycerium (New Phyt., vol. xii, p. 311, &c.). It was 
found that in PL alcicorne , one of the less robust species, the vascular 
Text-fig. 9. a. Sections of rhizome of Platycerium alcicorne, showing relation of two leaf- 
traces to the ring of meristeles of the axis. B. similar sections from Platycerium aethiopicum, showing 
the greater complexity with numerous medullary strands. After Miss Allison, New Phytologist, 1914. 
system of the axis is a simple dictyostele, but very highly perforated (Text- 
fig. 9, a) ; on the other hand, in PI. aethiopicum ) one of the most robust 
species, there is in addition a very complex medullary system (Text-fig. 9, B). 
As Miss Allison has pointed out, a comparison may be drawn with Matonia 
and Dipteris thus : ‘ Anatomically Dipteris is relatively simple , its simple 
solenostele is replaced by several concentric solenostelic cylinders in Matonia. 
In many other phyletic lines it may be seen how the solenostele becomes 
broken up into a dictyostele. It would be quite consistent with the 
structural facts here described, if we were to consider Platycerium with its 
complicated dictyostele as the dictyostelic type of a series of which Dipteris 
and Matonia are the solenostelic types’ ( 1 . c., p. 323)* • This seems to be 
a very reasonable interpretation of the facts so far as known; widespiead 
e perforation ’ would be an important factor in leading to the conditions 
described for Platycerium . Moreover, the fact that such perforations do 
occur in the petiole of Dipteris Lobhiana and of Cheiropleuria\y&v£. a special 
