Salmi'.—On the Branching of the Zygopteridean Leaf. 373 
Stauropteris was thus considered to possess pinna-traces facing parallel to 
the main petiolar trace, and an attempt was made (Bertrand, 1909 , p. 177) 
to explain what was regarded as a surprising anomaly. 
Except for Stauropteris our knowledge of the Zygopteridean leaf is 
still confined to its basal region, and it is too early to generalize as to the 
probable mode of branching of the distal (laminated) portions of the frond. 
It is to be borne in mind, however, that a number of frond genera from the 
same rocks as these raches still remain to be correlated, and that these 
fronds do not differ materially, in the orientation of their segments, from 
those of any living Ferns. There is thus a strong presumption that the 
distal (laminated) portions of the Zygopteridean leaf were in most cases 
held in a more or less horizontal position, all their segments being expanded 
in the same plane, as in the modern Ferns. The suggestion put forward by 
Kidston and Gwynne-Vaughan ( 1910 , p. 474), that the peculiar habit of the 
Zygopteridean leaf is to be attributed to an erect position, is probably 
applicable only to the basal wingless portion of the rachis, except in 
Stauropteris. If, as Dr. Scott ( 13 ) has suggested, there were two kinds of 
leaves, sporangiferous and vegetative, the former appear to have been held 
strictly erect, at least in the last-named genus. 
II. On the Probable Pinna Nature of Gyropteris sinuosa , 
Goeppert. 
Having arrived at the conclusion that the embedded trace of Diplolabis 
and similar Zygopterids belongs to a secondary rachis completely enclosed 
in the primary cortex, the question arose whether any closely allied plant 
existed in which the secondary rachis became free from the main cortex 
before dichotomizing. After this I read for the first time a description 
of Gyropteris sinuosa (P. Bertrand, 1909 , p. 181) from the Carboniferous 
Limestone of Glatzisch-Falkenberg, originally described by Goeppert ( 4 ), 
and was struck by the fact that the shape of its xylem portion was almost 
identical with that of the pinna-trace of Diplolabis or Metaclepsydropsis , the 
two latter being almost indistinguishable one from the other. The degree 
of similarity is indeed so great that it seemed probable that G. sinuosa is in 
reality a ‘ pinna ’ enclosed within its own cortex , and belonging to a genus 
closely allied to, if not identical with, either Metaclepsydropsis or Diplolabis. 
The transverse section of the vascular strand of Gyropteris measures about 
1 cm. in length, i. e. more than four times as much as in Metaclepsydropsis , 
and if the above conjecture has any foundation, the complete plant of 
Gyropteris must be a giant among the family. 
Dr. Bertrand naturally did not fail to notice the resemblance mentioned 
above, but he dismissed as improbable the idea that G. sinuosa is a 
secondary rachis, and provisionally regarded it as a separate genus. The 
