A rchangiopteris Henryi and other Marattiaceae. 263 
the Polypodiaceae and Cyatheaceae ; the curve that they outline being 
but a slight variation of the horseshoe design so frequently met with in 
these two orders. In the enlarged basal region of the petiole, however, 
a new feature is introduced by the occurrence of one or more internal 
vascular strands lying within the typical curve (Fig. 8). These internal 
strands arise as branches from the inside of the median abaxial strands of 
the curve, but they do not lie in the course of the curve itself, nor can they 
be considered as forming part of it. Two such strands are usually present 
(Figs. 9 and 10), but in one case as many as five were observed (a, b, c, d, e 
in Fig. 8). They were arranged in an arc concentric with the abaxial part 
of the typical curve. Two of them (a and d ) ended blindly above, and two 
others (b and c) fused together, so that here also only two internal strands 
eventually remained. As they pass upwards these internal strands in all 
cases gradually move across the central ground-tissue towards the adaxial 
side of the petiole, and before the top of the pulvinus is reached they fuse 
with the two terminal incurved strands of the typical arc (xx in Figs. 9 and 
to). In a few cases a single strand alone arose from the abaxial strands 
of the typical curve, but this soon divided into two which behave as before. 
The protoxylems of the internal strands first of all face outwards, towards the 
abaxial surface of the petiole (Fig. 8), but as they advance across the internal 
ground-tissue they gradually turn round so as to face in the same direction 
as the terminal strands with which they fuse (Figs. 9 and 10). The internal 
strands may fuse with either end of the terminal strands according as the 
protoxylems of the latter face towards the sides of the petiole (Fig. 9) or 
towards its median plane (Fig. 10). In the region above the pulvinus all 
the strands present in the petiole belong to the typical curve. The two 
terminal strands sink in towards the centre of the petiole, and at a point 
higher up they fuse together across the median plane to form a single large 
internal strand with the protoxylem on its adaxial side, as described and 
figured by Bertrand and Cornaille 1 . 
In A rchangiopteris two vascular strands only are given off from the 
dictyostele of the stem to supply each leaf. As they pass outwards they 
divide up into several (8 or 9) separate strands which are arranged at the 
base of the leaf in a typical horseshoe-shaped curve, entirely similar to that 
in Kaulfussia (Fig. 11). The terminal strands of the curve (xx in all the 
figures) advance towards the median plane of the petiole, and at one point 
in the pulvinus they fuse together to form a single broad strand the 
protoxylems of which face abaxially (Fig. 13). Higher up they become 
separate again, and curving gradually inwards they turn round at the 
same time so that their protoxylems face towards the sides of the petiole 
(Fig. 14). 
1 Etudes sur quelques caracteristiques de la structure des Filicindes actuelles. moires de 
l’Universitd de Lille, tom. x, Mem. 29, pp. 151 et seq., 1902. 
