KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 57. NIO |. 21 



figured in connection with a detailed description, it is at any råte certain, that of all 

 plant-remains Psilophyton princeps, even in the narrower delimitation, comes nearest to 

 the Röragen specimens described above. 



The numerous statements made by Dawson regarding the distribution of Psilo- 

 phyton princeps in North America must be thoroughly revised. White, after a critical 

 review of the evidence, declares that he has seen typical Psilophyton besides from Gaspé 

 only from the Hamilton of Maine and New York [the specimens described by Pen- 

 hallow (1893) as P. grandis], Numerous specimens found in the Old Red Sandstone of 

 Scotland ha ve been referred to this species; but in no case is there any sufficient proof 

 of specific identity. Lycopodites Milleri is certainly not specifically identical: this plant 

 has even recently (1914) been referred to a new genus - - Thursophyton — by Prof. Nat- 

 horst. P. Bertrand (1913) records Psilophyton princeps, on what appears to be good 

 evidence, from Matringhem in Northern France, and finally it has been identified by 

 Prof. Nathorst (1914) in a collection from the little archipelago of Bulandet in 

 Western Norway. All the specimens referred by Bureau (1914) to this species are 

 doubtful. 



The species shows a close agreement with Arthrostigma gracile: it may be asked 

 whether the two forms may not be not only generically but even specifically identical, 

 a possibility which is al so discussed by White. They are kept here in separate genera 

 because of the occurrence of a vein in some of the leaves of Arthrostigma and the charac- 

 teristic structure of the stem of that plant. 



Psilophyton Goldschmidtii n. sp. — Text fig. 2; pl. 2, fig. 6?; pl. 4, fig. 15? 



Nathorst 1913, p. 26; pl. 3, fig. 3. 



It seems to be necessary to describe as a separate species of Psilophyton the inter- 

 esting specimen figured by Prof. Nathorst in pl. 3, fig. 3. of his preliminary report on 

 the Röragen flora and refigured in this paper (text-fig. 2). Its chief characters are em- 

 bodied in the following diagnoser 



Branch-system consisting of a well developed, probably sympodially formed main 

 axis and lateral branches. Lateral branches dividihg dichotomously at a short distance 

 from the axis and again repeatedly bifurcating under rather wide angles, probably in one 

 plane, their whole system of ramifications having a spreading habit. Main axis and some- 

 times the basal part of the branches bearing narrowly conical to subulate spines up 

 to 4 mm. long. 



The main axis agrees closely with the stems and branches of typical Psilophyton 

 princeps. The spines are very similar to those of that species, possibly somewhat finer 

 and more pointed. Their arrangement cannot be distinctly made out: they appeartobe 

 irregularly placed but it is possible that their disposition was a spiral one. In so far as 

 the main axis alone is regarded, the difference from Psilophyton princeps is not so great 



