KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 57. N:0 |. 25 



Dawson in a passage in the diagnose of Psilophyton princeps in the paper mentioned, 

 which passage is quoted above, in p. 16. Both these supposed fructifications and the 

 real Psilophyton princeps occur at Röragen, but there is as little evidence that they 

 belong to the same kind of plant in the Norwegian locality as there is at Gaspé, or at 

 Matringhem in Northern France, from which locality both forms have been recorded 

 by P. Bertrand (1. c). A comparison of the sporangium-bearing specimens 1 at Eöragen 

 with spine-bearing specimens of Psilophyton princeps even gives the result that there 

 are certain differences which speak against a specific identity. Under these circumstan- 

 ces a new provisional name must be created for these fossils, which, with the exception 

 of the spine-bearing branches, represent the only well characterized type among the 

 whole höst of heterogeneous plant-remains referred by various authors to Psilophyton 

 princeps. The name Daivsonites is here proposed as a provisional generic designation 

 for these sporangium-bearing specimens which all seem to be sufficiently similar to be 

 referred to one species, Daivsoiiites arcuatus. 



Diagnose. 



Sporangium-bearing branch-systems, dividing dichotomously, or differentiated 

 into a sympodially formed main axis and bifurcating lateral branches. Ultimate bran- 

 ches slender and curved, bearing terminal capsules of a narrowly obovoid or short fusi- 

 form shape and usually 3 — 5 mm. long. 



Description of specimens. 



The most interesting specimen is the one shown in natural size in pl. 3, fig. 1, a part 

 of which is represented twice enlarged in fig. 2 of the same plate. It consists of three 

 rather thick main branches or stems giving off more slender lateral branches. The main 

 branches, although probably formed in a sympodial mariner, are straight and well de- 

 fined. They are about 3 mm. broad on the impression and are markedly striated longi- 

 tudinally. Tlie striae are caused by elevated ridges representing firmer internal strands 

 or surface elevations which are now replaced by some mineral matter. The number of 

 these ridges is usually four in the lower part of the main branches. In fig. 2, to the right, 

 it can be seen that one of these ridges continues out into the lateral branch. The lateral 

 branches are only partly preserved; but close to them can be seen at least two groups of 

 curved ultimate branches and sporangia (sp. in the figures). — ■ A distinctly defined 

 main branch or rachis is seen in pl. 4. fig. 18. The difference in size between the main 

 branch and the lateral branches is even greater than in the specimen just described. 

 The main branch shows a similar but somewhat finer and denser striation. There is no 

 doubt that the lateral branches bear sporangia, but these are rather poorly preserved. 



In fig. 7, pl. 3, is shown, three times enlarged, a part of the surface of another piece 

 of slate with remains of several sporangia attached to the ultimate branches. The ulti- 



1 These structures have not been shown to contain spores, and it cannot be regarded as proved that 



they are sporangia. It is, however, probable that this is the case, and for the sake of brevity the term 

 sporangium will be used in the following pages. 



K. Sv. Vet. Akad. Harull. Band 57. N:o 1. 4 



