Bower. — Studies in the Phytogeny of the Filicales. 525 
especially in the curiously modified epiphytes of the genus Platycerium. 
In Cheiropleuria a scandent tendency has been seen, though it does not 
appear to have led to any definitely climbing or epiphytic state. But 
Platycerium has its shoot strongly modified in relation to epiphytic life, 
as shown particularly in its peculiar leaves. Nevertheless, externally 
a similarity to Dipteris and Cheiropleuria may be traced, not only in the 
outline of the erect or pendent leaves, with their regular bifurcation, but 
also in the venation ; and this may be traced even in the highly modified 
nest-leaves. Perhaps it is in the newly-described species, P. Sumbawense 
n. sp. Christ (Warburg, Monsunia, i, 1900), that the similarity between the 
fertile leaves and those of Dipteris is the most marked. For there the 
narrow lamina is repeatedly furcate, so that the lacineae may number 
twenty on a single frond, and all are soriferous; this is reminiscent of the 
simpler species of Dipteris , such as D. Lobbiana. The comparison already 
made of the juvenile leaves of Cheiropleuria with those of young plants of 
Dipteris and of Platycerium supports the similarity still further, and it is 
apparent also in the mature leaves of D. conjugata , of Cheiropleuria , and 
even in some measure in the nest-leaves of Platycerium. 
But the anatomical comparison of the axis shows marked divergence 
of character in Platycerium from what is seen in Cheiropleuria or Dipteris. 
As Mettenius has shown, and Tansley has quoted in his Lectures on the 
Filicinean Vascular System (p. 62), the axis of P. alcicorne is highly dictyo- 
stelic, and perforated. There is, as a result, an almost simple ring of 
meristeles, while the leaf-trace, with certain complications at its origin, 
comes off ab initio as a number of detached strands (Text-fig. 9, a). 
Miss Allison (New Phyt., 1913, p. 311) has recently published a descrip¬ 
tion of this with figures, and has also described the vascular system for 
P. aethiopicum. In the latter the structure is still more complex, for the 
leaf-trace consists of still more numerous strands, while a large number of 
medullary strands are present at the centre of the axis (Text-fig. 9, B). 
A comparison of the structure of these species with the states seen in 
Matonia and Dipteris suggests that the relatively simple ring of meristeles 
seen in P. alcicorne finds its correlative in the simple solenostele of Dipteris ; 
while the more complex system in P. aethiopicum , with the numerous 
medullary strands in addition, finds its correlative in the polycycly of 
Matonia. Imagine these genera with their solenosteles profusely 4 per¬ 
forated *, and something very like the stem structure of the species of 
Platycerntm would be the result. Clearly Platycerium , on such an interpre¬ 
tation, takes anatomically a more advanced position than Dip ter is, or Matonia , 
and a still more decidedly advanced position than Cheiropleuria} 
1 See The Genus Alcicornium of Gaudichaud, by L. Underwood. Bull. Torrey Club, vol. xxxii, 
1906, P» 587* &c. Underwood desires to retain the name Alcicornium, Gaud., in place of Platy- 
ceriumy Desv. But I follow Christensen’s Index in retaining Platycerium as the generic name. 
