CUTICLES or CTCADEAiS' FEO:?^DS. 



203 



Fig. 13. Zamia mitricata. Lower cuticle^ showing a stoma in section. Note the slightly sunk 



guard-cells. 



Fig. 14. Macrozamia cylindrical Section through a stoma, showing two intercalated series of cells and 



the long narrow air-space. 

 Fig. 15. The same. Upper cuticle in surface view^ showing variation in the thickness of the cell-walls^ 



also pitting and layering of the walls. 



Plate 19. 



[Camera lucida drawings of stomata of fossil fronds.] 



Fig. 1. Ptilophyllum pecten. Showing the different thickenings of the guard-cells and the tliin places 



above the poles. Specimen from Marske. x 600. 

 Fig. 2. Zamites sp. Showing outlines of stomatal thickenings. From scale-leaves on stem. Specimen 



in the Naturhistoriska Rilismuseum, Stockholm, x 500. 

 Fig. 3. Otozamites Feistmanteli . Stoma with differences of thickening less marked. The subsidiary cells 



are not thickened. Specimen from Marske. x 500. 

 Fig. 4. Otozamites graphicus. The sides of the pore appear to have been slightly cuticularised. 



Specimen from Marske. x 500. 

 Fig. 5. Anomo zamites Nilssoni. Showing thin subsidiary cells and thin places at the poles. Specimen 



from Gristhorpe. x 500. 

 Figs. 6-8. Dictyozamites Hawelli. Subsidiary cells thickened : 6 and 8 show projections from upper 



thickenings of guard-cells. Fig. 7. Stoma seen from mesophyll side. Specimens from 



Marske. X 500. 

 Fig. 9. T(Bniopteris major. Compare with 7\ vittata. Specimen from Gristhorpe. x 500. 

 Figs. 10-12. Taniopteris vittata. Showing the similarity with stomata of other Bennettitalean fronds. 



Fig. 10 is seen from the mesophyll side. 



Mar 



X 500. 



Figs. 13, 14, 18. Nilssonia sp. From a specimen found at Roscberry Topping, x 500. Note in 13 the 



series of overarching subsidiary cells. Figs. 14 and 18 show the guard-cells as seen from 



the mesophyll side of the epidermis. 

 Fig. 15. Nilssonia mediana. Subsidiary cells with thickened tips overarching the guard-cells. 



Specimen from Marske. X 500. 

 Figs. 16, 17. Ftilozamites Leckenbyi. Stomata as seen from upper (17) and lower side (16). In the 



former the guard-cells can just be seen through the opening. Specimens from Gristhorpe, 



X 500. 

 Fig, 19. Ctenis falcata. Showing thick wall of cuticle round the stomatal cavity. Specimen from 



Gristhorpe. x 500. 



Plate 20. 



[Photomicrographs of cutlcular preparations of fossil fronds.] 



lophylh 



ight) and lower epidermis with the 



Fig 



stomata arranged in regular rows. From Marske. X 25. 



Upper epidermis more highly magnified, showing sinuous outlines of the 



cells. X 170. 



Fig. 3. P tilophyllum pecten. Part of lower epidermis more highly magnified, showing stomata. 



X 200. 



Fig. 4. Ptilophyllum sp. Showing rows of circular hair-scars with epidermal cells below. From Marske 



X 200. 



SECOND SERIES. — BOTANY, VOL. YIII. 2 H 



