372 MR. T. W. WOODHEAD ON THE 
Figs. 17, 19, 21, 23, 25, & 97. 
Fig. 17. T. S. leaf-stalk from exposed situation of Gritstone Plateau. 
18. T. S. portion of the same; x 150 diam. 
19. T. S. leaf-stalk, Oak-wood form. 
20. T. S. portion of the same ; x 150 diam. 
21. T. S. leaf-stalk from a very large frond from a moist Oak wood. 
L = lacune. 
22. T. S. portion of 21; x 150 diam. 
23. T. S. leaf-stalk of an immature shade-form. 
24. T. S. portion of 23; x 150 diam. 
25. T. S. leaf-stalk, mature shade-form. 
26. T. S. portion of 25; x 150 diam. 
27. T. S. slender leaf-stalk, Oak-wood form. 
28. T. S. portion of 27; x 150 diam. 
