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201 



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EXPLANATION OP PLATES 17-20. 



[The figures in Plates 17-19 were drawn with the aid of a camera lucida, the magnification being 



450 diameters, unless otherwise indicated. The following abbreviations are used:—/), polar 

 subsidiary cells ; I, lateral subsidiary cells ; d, dorsal lignified lamellae of the guard-cells ; 

 V, ventral lignified lamellse ; ff, guard-cells ; s, stoma-opcning ; i, intercalated subsidiary cells ; 



«, air-space.] 



Plate 17. 



Fig. 1. Stangeria paradoxa. 



characteristically 



thickened appearance due to the lignified lamellae of the guard-cells. Note the radiating 

 striae at the poles of the stoma, due to folds in the cutin layer. 

 Fig. 2. The same. A hair-scar from the under side of the leaf in surface view, showing the radiating 



folds of the cutin. 

 Fig. 3. The same. Upper cuticle in surface view, showing the characteristic undulated walls of the 



epidermal cells and the striations due to folds in the cutin. 

 Fig. 4. The same. Upper cuticle in section. Note the irregular appearance of the cutin layer due to 



fold i n g. 



