4 ARKIV FÖR BOTANIK. BAND 17. NIO 3. 



maximum length is 6 cm. The difference seems to be greater 

 between E. intermedius and E. Münsteri than between E. 

 intermedins and E. Mohergii. As for the two other species, 

 which are nearly related to E. Mohergii: E. Lyellii and E. 

 Bunhuryanus, see the paper by Möller and Halle (1913). 



Neocalamites Nathorstii sp. nov. 



PI. 1, figs. 9—14. 



Stems articulate, with few branches; internodes on the 

 impressions minutely striated and with 8 — 16 fairly distinct 

 longitudinal furrows; their length about 40 — 70 mm, their 

 breadth 10 — 20 mm. Nodes mostly of the same breadth as 

 the internodes. Leaves free down to their bases, their number 

 12 — 24, their breadth 1,5 mm, their length in most cases more 

 than 50 mm. 



In some pieces of rock there are found rather small and 

 gracile fragments of branches or stems belonging to this 

 species. Here the breadth of the internodes is about 2 mm 

 and the length 20 — 30 ram. The leaves are 1 mm broad, 

 at least 3 cm long and standing out at right angles from 

 the axis. 



The material of Neocalamites Nathorstii was collected by 

 Prof. Nathorst at Whitby, Yorkshire, in 1909, and by Prof . 

 Halle in the same place in 1910. Through this discovery 

 of Prof. Nathorst's the genus Neocalamites has been proved 

 to exist as late as about the middle of the Jurassic period. 

 The other species of the genus are from the Rhaetic {N. 

 hoerensis (Schimp.) Halle, N. Carrerei (Zeill.) Halle, iV. 

 Knowltonii Berry) or from the Keuper (iV. Meriani (Brogn.) 

 Halle, N. virginiensis (Fontaine) Berry). The fossiliferous 

 rock is a coarse arenaceous shale, in which the impressions 

 are not so distinct as in the case of Equisetiies intermedins. 

 In the same pieces of rock are also to be found the remains 

 of many other plants. 



Prof. Halle has shown that in Neocalamites as well as 

 in some species of Equisetites from the Lower Mesozoic there 

 is a greater number of longitudinal furrows on the internodes 

 (= impressions of the fibrovascular bundles of the central 



