PKOTOPTEKIS. 69 



"We may briefly define Protopteris as follows : — 



Stems of tree-ferna 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-soars 

 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, Velenovsk^, and Staub 

 in adopting the generic name of Dichsonia, I have provisionally 

 placed Protopteris in the Cyatheaoecs on account of its resemblance 

 to Dichsonia antarctiea, Labill. 



1.— Protopteris Witteana, Schenk. 



1871. Protopteris Witteana, Sohenk, Palffiontographica, vol. six. p. 226, 



pi. XXI. figs. 6 and 6a. 

 1874. Protopteris (?) Witteana, Schimper, Trait, pal. v%. toI. iii. p. 526. 

 1880. Protopteris Witteana, Hosius and Von der Marck, Palseontographica, 



vol. xxvi. p. 206. 

 1883. Protopteris Witteana, Renault, Cours hot. foss. vol. iii. p. 75. 

 1890. Protopteris Witteana, Staub, Foldt. Kozl, 1890, p. 230 (German text). 



This species is thus defined by Schenk ' : — 



" Truncus arboreus erectus, inter pul vinos radicibus adventitiis 

 vestitus, petiolorum pulvini oblongi spiraliter dispositi, cicatrices 

 ovales, fasciculus flbrovasalis sinuosus cornubus inflexis." 



Type. Portions of structureless stems. Collection of Obergeriohts 

 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 5 cm. 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 Palseontographica, vol. xix. p. 226. 



