70 PROTOPTERIS. 
the form of the leaf-trace being the chief characteristic on which 
the species was founded. 
In the British Museum Collection there are three specimens 
which I have referred to Schenk’s species ; two of these are simply 
casts without any minute structure, but the other is in a much 
better state of preservation and enables us to amplify the original 
diagnosis of the species. 
Stem with a central axis consisting of band-form vascular 
bundles enclosing a fairly large pith; from these vascular plates 
branches pass out to the petioles, and in a surface-view of a leaf- 
stalk base the leaf-trace is shown to present more or less clearly 
the characteristic horse-shoe pattern. 
The oval petiole scars are arranged fairly closely; towards the 
periphery of each is a single vascular bundle of the horse-shoe 
form, but differing from that of P. punctata in the absence of the 
distinct constriction which occurs in each limb of the leaf-trace ; 
the free upper ends of the leaf-trace are distinctly curved inwards. 
Sections of adventitious roots occur in the lower part of the petiole 
scars. Between the leaf-bases there is a mass of filamentous tissue, 
traversed here and there by irregularly disposed roots. 
Before describing in detail the specimens of Protopteris Witteana 
in the National Collection, it should be pointed out that they 
appear to differ in no very important characters from the widely- 
spread P. punctata. Possibly the Wealden specimens at present 
referred to the species instituted by Schenk, may eventually find 
their proper place under P. punctata; but at present we may 
regard the slight difference in the pattern of the leaf-trace bundles 
of the two forms as sufficient reason for the retention of Schenk’s 
Wealden species. 
In Protopteris punctata, Sternb., we have one of the best known 
fossil tree-ferns. The species was first instituted by Presl for a 
plant previously figured and described by Sternberg as Lepido- 
dendron punctatum.'  Sternberg’s specimen was for some time 
referred to as having been obtained from Bohemian rocks of 
Carboniferous age; another example of the same plant from 
Greenland was regarded by Heer, in the third volume of the 
‘¢ Flora fossilis Arctica,” as indicative of Carboniferous rocks. It 
was, however, shown by Krejci and Feistmantel that the coal- 
1 Sternberg, Flor. Vorwelt, Heft i. p. 20. 
