268 G wynne- Vaughan.— On the Anatomy of 
complex than that described above. With this reservation the mature 
stem of Archangiopteris maybe said to present a simpler structure than 
that of any of the other Marattiaceae. In fact it still retains at maturity 
a stage rapidly passed through by the young plants of the other genera. 
It has been shown that in young plants of Angiopteris , Marattia , and 
Danaea 1 there is a stage with a single internal strand only, which itself 
fuses with each leaf-gap margin ; just as in the mature stem of Archangi- 
opteris. The mature stem of Kaulfussia, although it only contains a single 
internal strand, is a stage in advance of Archangiopteris , for here the 
internal strand runs freely and continuously through the central ground- 
tissue, and is only connected with the leaf-gap margin by means of 
branches. 
The vascular system of the petiole is also comparatively simple both 
in Archangiopteris and Kaulfussia , the arrangement of the strands being 
based upon a simple horseshoe-shaped curve comparable to that typical for 
the Cyatheaceae and Polypodiaceae. It is clear also that the further increase 
in complexity that occurs is not due to any alterations in the outline of this 
curve, but to the formation of an altogether new system of internal strands 
which arise from the inside of those of the original curve. 
Miss Shove (1. c.) has stated that in the base of the petiole of Angiop- 
teris the internal strands are seen to arise from the outer ring, and the same 
thing has been said of Marattia fraxinea by MM. Bertrand and Cornaille 
(1. c.). There is very little doubt, therefore, that in these genera also the 
outer ring of strands represents the same original curve, which remains 
comparatively simple throughout the order. It is certain also that the 
internal petiolar strands have no direct connexion with those in the stem. 
The initial appearance of these strands probably took place in the basal 
region of the petiole, and it is suggested that Archangiopteris and Kaul- 
fussia represent an early stage in which they are still confined to the basal 
pulvinus. The more or less internal strands that occur in the upper part of 
the petiole of these two plants really belong to the original horseshoe- 
shaped curve, and are not to be confused with those found in the basal 
pulvinus, nor with those that occur practically throughout the petiole in 
Marattia and Angiopteris. With this exception my observations are 
thoroughly in accord with the conclusion arrived at by Bertrand and 
Cornaille — that these internal petiolar strands of the Marattiaceae are 
not strictly comparable with anything to be found in the petioles of the 
leptosporangiate Ferns, nor, in my opinion, are they comparable with 
the internal strand found in the petiole of Helmin thostachys. 
There is no essential difference between the Marattiales and the 
Filicales as regards the origin and final distribution of the vascular strands 
1 Farmer and Hill, 1. c., p. 376. Brebner, l.c., p. 530. Jeffrey, ‘The Structure and Develop- 
ment of the stem in the Pteridophyta and Gymnosperms/ Phil. Trans., vol. 195, p. 120, 1902. 
