PROTOPTERIS. 69 
We may briefly define Protopteris as follows :— 
Stems of tree-ferns characterized by a central vascular cylinder 
consisting of band-form bundles variously arranged. The surface 
of the central axis is covered by spirally arranged leaf-scars 
separated by, and occasionally embedded in, a mass of ramenta 
and adventitious roots. The leaf-trace, as seen on the surface of 
the petiole scars, has a horseshoe-like form which presents certain 
modifications in the pattern according to the species. 
The genus appears to range from the Permian to the Lower 
Cretaceous. 
Without following the example of Heer, Velenovsky, and Staub 
in adopting the generic name of Dicksonia, I have provisionally 
placed Protopterts in the Cyatheacee on account of its resemblance 
to Dicksonia antaretica, Labill. 
1.—Protopteris Witteana, Schenk. 
1871. Protopteris Witteana, Schenk, Paleontographica, vol. xix. p. 226, 
pl. xxx. figs. 6 and 6a. 
1874. Protopteris (?) Witteana, Schimper, Trait. pal. vég. vol. ii. p. 526. 
1880. Protopteris Witteana, Hosius and-Yon der Marck, Palsontographica, 
vol. xxvi. p. 206. 
1883. Protopterrs Witteana, Renault, Cours bot. foss. vol. iil. p. 74. 
1890. Protopteris Witteana, Staub, Féldt. Kozl, 1890, p. 230 (German text). 
This species is thus defined by Schenk * :— 
‘Truncus arboreus erectus, inter pulvinos radicibus adventitiis 
vestitus, petiolorum pulvini oblongi spiraliter dispositi, cicatrices 
ovales, fasciculus fibrovasalis sinuosus cornubus inflexis.” 
Type. Portions of structureless stems. Collection of Obergerichts 
director Witte, Hanover. 
The type specimen, from the Hastings Sands in the neighbour- 
hood of Hanover, is described as being considerably compressed, 
with a length of 19 cm. and a breadth of 5cm. The petiole scars 
are oval in form, and arranged in a fairly close spiral. The form 
of the leaf-trace is distinctly shown in many of the leaf-bases ; 
between the latter are several scars marking the points of attach- 
ment of adventitious roots. Schenk’s specimen shows no structure; 
1 Paleontographica, vol. xix. p. 226. 
