TEMPSKYA. 155 
specimen of Protopteris Witteana already described, which has 
its minute structure partially preserved, there is certainly a general 
resemblance in texture and manner of preservation to Zempskya 
Schimper?, and such adventitious roots as occur in the neighbour- 
hood of the Protopteris petiole scars appear to agree with those 
of Corda’s species. 
The figure of a transverse section of a small root of Zempskya 
given by Velenovsky (pl. vi. fig. 6) is rather of the nature of a 
diagrammatic than a very accurate sketch; it gives a very im- 
perfect idea of the structure of the central vascular axis. He 
also figures in the same diagrammatic fashion a section of a 
Dicksonia antarctica root; here again the xylem is not shown at 
all clearly. In the better specimens of Zempskya Schimperi which 
I have examined, and in sections of fresh Dicksonia antarctica roots, 
there is a very close agreement in structure; in both there is a 
well-marked diare vascular bundle, and in both a strengthening 
ring of sclerenchyma, with parenchyma on the outside. In pl. vi. 
fig. 5 of his paper, Velenovsky figures what he describes as the 
main axis of a root with a horseshoe vascular bundle; this seems 
to me much more probably a section of a petiolar structure; the 
form of the vascular bundle is entirely different to that which we 
find in the adventitious roots of such ferns as Dicksonia antarctica. 
Through the kindness of the Director of the Royal Gardens, 
Kew, and of the Assistant-Curator, Mr. Watson, I have lately had 
the opportunity of closely examining some specimens of Dicksonia 
antarectica. In one case Mr. Watson had a well-grown stem, 
twenty-five years old, taken out of the ground; we found that 
just below the surface of the soil the basal part of the axis became 
swollen owing to the greater number of adventitious roots which 
clothed the lower part of the stem. The central vascular cylinder 
was prolonged almost to the bottom of the underground mass of 
roots, tapering towards its somewhat oblique termination. 
We did not find any mass of roots below the surface, which 
was without a central or excentric vascular axis for a sufficient 
length to account for even the smaller specimens of Zempskya. 
In the case of older and larger plants of Dicksonia, Mr. Watson 
tells me that in such cultivated examples as he has noticed there is 
usually a large ball-like mass of roots below the surface, but these 
do not extend for more than a short distance, either vertically 
downwards, or in an oblique direction, without any vascular 
