THE FOSSIL OSMUND ACE^Fl 779 



Plate I. 



Fig. 1. Osmundites Dunlopi. Surface view of the specimen, a., outer limit of stem. (Natural size.) 

 Fig. 2. Osmundites Dunlopi. A transverse section of the specimen, a., outer limit of stem ; xy., xylem 



ring of the stele; S.L., zones of scale-leaves; scl., conspicuous sclerotic strands in the outer leaf-bases. 



( x about 3.) Slide in the collection of Mr R. Dunlop. 



Fig. 3. Osmundites Dunlopi. Portion of the xylem ring showing the departure of the leaf-trace xylem. 



(x36.) Slide K/1242.* 



Plate II. 



Figs. 4 and 5. Osmundites Dunlopi. Portion of the xylem ring showing the departure of the leaf-trace 

 xylem. (Fig. 4, x 31, slide K/1243 ; fig. 5, x 36, slide K/1242.) 



Figs. 6, 7, 8. Osm,undites Dunlopi. Longitudinal sections of the xylem ring showing the departure of the 

 leaf-trace xylem. st. xy., stem xylem ; It. xy., leaf-trace xylem. (x9.) Slides K/l 246, K/l 244 (figs. 7-8). 



Fig. 9. Osmundites Dunlopi. Transverse section of small portion of the xylem ring showing the pit- 

 markings on the walls of the tracheides. ( x 90.) Slide K/1243. 



Figs. 10 and 11. Osmtmda cinnamomea. Longitudinal sections of the xylem showing the multiseriate 

 pitting of the tracheides. (Fig. 10, x 144 : fig. 11, x 155.) 



Fig. 12. Osmundites Dunlopi. Oblique section of a leaf-trace passing through the inner cortex to show 

 the apparently porose pitting of the tracheides. ( x 63.) Slide K/1243. 



Fig. 13. Osmundites Dunlopi. Transverse section of a leaf-trace passing through the inner cortex to show 

 the origin of the root steles, en., endodennis. ( x 20.) Slide in the collection of Mr E,. Dunlop. 



Plate III. 



Fig. 14. Osmundites Dunlopi. Transverse section of four leaf-bases in close proximity to the stem. 

 (xl6.) Slide K/1243. 



Fig. 15. Osmundites Dunlopi. Transverse section of leaf-trace (A) in fig. 14 more highly magnified. 

 scl, sclerotic ring of the petiole. ( x 33.) Slide K/1243. 



Fig. 16. Osmundites Dunlopi. Portion of the coating of leaf-bases to show the sclerotic stands (sc. st.} 

 scattered in the spaces once occupied by stipular parenchyma, scl., sclerotic rings of the petioles ; It. xy. y 

 xylem of leaf-trace. ( x 33.) Slide K/1243. 



Fig. 17. Osmundites Gibbiana. Surface view of specimen. (Natural size.) 



Fig. 18. Osmundites Gibbiana. A transverse section of the specimen, a., outer limit of the stem; xy. t 

 xylem ring of stem ; S.L., zones of scale-leaves. ( x 2'5.) Slide K/1249. 



Fig. 19. Osmundites Gibbiana. Portion of xylem ring of stele, en., endodermis. ( x 33.) Slide K/1249. 



Plate IV. 



Fig. 20. Osmundites Gibbiana. Portion of coating of leaf-bases to show the sclerotic strands (sc. st.) in 

 the spaces once occupied by stipular parenchyma, scl., sclerotic rings of the petioles ; It. xy., xylem of leaf- 

 trace ; S.L., scale-leaf. ( x 14.) Slide K/1249. 



Fig. 21. Osmundites Dowkeri. Transverse section of the stock, a., outer limit of stem; xy., xylem ring 

 of stele. The pith (p.) is still preserved. ( x about 2.) Slide K/1248. 



Fig. 22. Osmundites skidegatensis. Transverse section, xy., xylem ring of stele ; p., the pith (still intact) ; 

 int. str., internal vascular strands. ( x 2 - 4.) Slide K/1251. 



Fig. 23. Osmundites skidegatensis. Portion of the vascular ring of the stem. ext. ph., external phloem ; 

 int. ph., internal phloem ; int. str., internal vascular strands ; scl. 1 , sclerenchyma between xylem strands of 

 normal vascular ring ; scl. 2 , sclerenchyma between the internal vascular strands. ( x 14.) Slide K/1251. 



* Slides indicated by a " K " in the collection of Mr R. Kidston. 

 TRANS. ROY. SOC. EDIN., VOL. XLV. PART III. (NO. 27). Ill 



