KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 45. NX) 7. 5 



agreement with Marsilia, and the pinna? may have been spread out horizontally. In 

 other specimens the pinna? are borne in a different manner. The bundle of the 

 petiole forks into two branches, these divide again into strands forming the midribs 

 of the pinna?. In such specimens the leaf appears divided dichotomously. In the 

 specimen fig. 14 this is clearly seen. In this case the pinna? appear more conspi- 

 cuously arranged in the plane of the petiole and not spread out horizontally. It 

 is only in agreement with this arrangement, that the outer pinna? show a strong as- 

 symetry in the development of the lamina. In fig. 14 the midrib of the outer pinna? 

 is seen to run close to the inner margin of the lamina. 



The tissue of the leaves is often preserved as a carbonaceous film which, in 

 favourable cases, may be removed from the matrix. If this film is treated with 

 nitric acid and chlorate of potash and afterwards transferred to ammonia, it shows 

 the outlines of the epidermal cells very clearly. The cells of the upper side are 

 uniform, rectangular or square in shape, with straight walls. No stomata have been 

 observed on the upper surfaee. In the epidermis of the lower side the cells are more 

 varying in shape. Rows of longitudinally elongated cells cover the midrib and the 

 lateral veins. In the fields, separated by these anastomosing stripes, the cells are 

 shorter, square or rounded, with somewhat sinuous walls. Only in these fields the 

 stomata are found. Figs. 1 — 4, pl. 3, represent the lower surfaee of the pinna? of 

 this species. In fig. 3 the broad zone of rectangular cells, covering the midrib is 

 visible. The cutiele of the upper side has not been removed, but is seen in some 

 places through the lower epidermis. In this specimen the cells of the anastomosing 

 stripes are comparatively short. Fig. 1 represents the lower cutiele of another spe- 

 cimen, separated from that of the opposite side. Fig. 2 shows part of the same 

 cutiele with stomata and anastomosing cell-rows, fig. 4 one of the stomata more 

 magnified. As appears from the figures, the stomata are of typical strueture. Their 

 number is comparatively small. 



Fig. 5, pl. 3 gives a surfaee view of the epidermal tissue on the lower side of 

 the petiole of a S. alata-iorm (the specimen pl. 1, fig. 5). It shows a broad zone of 

 longitudinal cell-rows in the middle, covering the midrib, and on both sides more 

 irregularly arranged, rounded or polygonal cells. The stomata are scarce and confined 

 to the lateral zones. Like in the full-grown leaves of S. undulata, they occur only 

 on the lower side. 



Sagenopteris dentata Nath. has been referred to here as partly a synonyme of 

 S. undulata. The species was founded in 1878 on three specimens from Bjuf, figured 

 in Prof. Nathorst's paper on the flora of that locality (4, pl. 2 figs. 5 — 7). One of 

 these specimens shows two leaflets connected at the base and resembles very much 

 S. undidata, save the more deeply dentate margin. The other two specimens 

 represent only fragments of detached pinna?. As they show a similar type of vena- 

 tion and the same characteristic teeth as the other specimen, they were also included 

 under the same species. In the third part of the Bjuf -Flora, S. dentata was, however, 

 identified with 8. undulata. 



