KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 51. N:o 10. 7 
only the Cycadophytes and the Ferns to choose between. Now, however, the question 
stands somewhat differently. We can, I think, feel confident in saying that the 
fossils in question are not Ferns, as no structures bearing resemblance to sori have 
ever been found, and as the whole appearance of the fronds and, above all, the 
thick cutiele and the structure of the stomata speaks against their belonging to this 
group. — I have discussed the systematical value of the structure of the cuticle and 
of the stomata in a previous paper (1914, p. 19), and therefore will not enter further 
irto these subjects here. — There is no reason why Ptilozamites should not be a cy- 
cadophytean genus, but, on the other hand, this is by no means certain. There is 
a great gap between Ferns and Cycadophytes,in the Palaeozoic bridged over by the 
Pteridosperms, and one could well conceive that Ptilozamites has its proper place here. 
In his Tonkin-Flora ZEILLER (1903, p. 51) placed the genus Ctenopteris SAP. 
among the Ferns, to be more exact in the group Odontopteroideae. He did this, 
however, only with great hesitation and with all reserve regarding its definite classi- 
fication, as he does not consider it impossible that the genus in question belongs 
to the Cycadofilices. He founds his classification partly and principally on its agreement 
with the genus Ctenis LINDLEY & HUTTON, in which RACIBORSKI (1894) found rounded 
tubercles, which in their opinion were sori, and partly on its resemblance to Dicho- 
pteris Z1IGNO, ”dont Pattribution aux Fougéres est généralement acceptée”. ”De plus”, 
he continues, ”on ne connait, parmi les Cycadinées fossiles, abstraction faite du genre 
Ctenopteris lui-méme, aucun genre å frondes bipinnées, et sil existe aujourd”hui une 
Cycadinée å frond bipinnée, le Bowentia spectabilis HOooKER, il faut connaitre que les 
Ctenopteris n offrent guére de resemblance avec elle.” 
Against this argumentation some remarks may be made. Even without anything 
turther, it is surely very problematical whether the tubercles in Ctenis which RAcI- 
BORSKI interpreted as sori really are such, and SEWARD (1900, p. 234) pointed also 
out that it was only a case of prominent, circular papillae in the cuticle. With 
"regard to the nature of Dichopteris opinions have, I think, never agreed. The supposed 
sori figured by ZiGNOo will hardly have definitively decided the systematical position 
of Dichopteris in anybody's opinion; and since SEwARD (1910, p. 550) expressed the 
opinion, which is shared by HALLE — according to a kind communication by Dr. HALLE, 
who has also examined the specimens in question — that they, without doubt, only 
constitute ”irregularities in the matrix”, the question is more open than ever. 
The reasons for which ZEILLER placed Ctenopteris among the Ferns are accordingly 
rather vague, and it may be confidently stated that several circumstances speak 
against the opinion of the genus belonging to this group. — I have dwelt somewhat 
on ZEILLER'sS discussion, as it is highly probable that Ctenopteris not only closely 
agrees externally but is also really nearly related to Ptilozamites. — Finally, I will 
once more point out that it is not easy to give a definite place in the system to 
either one or the other genus for the present. It is, however, most likely that both 
belong to the Cycadophytes or to an extinct plant-group closely related to these. 
As this paper only has reference to the Swedish species of Ptilozamites, I 
cannot speak of its extent, i. e. whether and, under such circumstances, which fossils 
