170 



MR. H. HAMSHAW THOMAS AND MISS N. BANCKOPT ON 



In M. cylindrica, in the 



of the lower surface, and also here and 



the upper surface of the pinnae, occur crystals of calcium oxalate (text-fig. 18) 



they 



appear to be contained in small isodiametric cells, and not in cavities, as in Dioon edule, 

 and in M. spiralis {—Fraserif), where the crystal-containing spaces are very small and 

 not at all frequent. 



Fig. 18. 



Maoozamia cylindrica. — Lower cuticle (from a nerve-course) in surface view, showing a crystal-containing 

 cell. (Cf. the form and arrangement of the cells with those shown in PI. 18. fig. 1-5, from the 



M. 



X450. 



The cutin layer is moderately thick (PI. 18. fig. 14 ; text-fig. 17), but, as usual, it 

 inner on the lower than on the upper surface of the leaves. 



Zamia, Linn. PI. 18. figs. 12 & 13; text-figs. 19-23. 



References .— Bornemann (1856), pp. 40, 43, 44; Taf. 11, figs. 7-15. Kraus (1866), pp. 41, 42; 



Taf. 22. 6gs. 24-27. 

 Species examined : — Z. Skinneri, Warsz.; Z. muricata, "Willd.; Z. Loddigesii, Miq.; Z. integrifolia, 



AM.; Z.Fischertj'Mifi.; Z. Ottonis,^i\(\.', Z. Lindem,^ege\j=Z. cylindrica, Jjiehvu. { = Leiboldiij 



Miq. ?). 



These 



eight 



species agree in essential characters 



of the epidermis. The cells in all 



are elongated in the direction of the longitudinal axis of the pinnae, and are three- or 



four-angular in shape. In Z, Ottonis the cells are somewhat irregular, with groups of 

 smaller cells here and there. In some species, for example Z. Skinneri (text-figs. 20 

 & 23) and Z. integrifolia (PI. 18. fig. 12), there is a marked distinction into two kinds 

 of cells, thin-walled and thick-walled. In Z. Skinneri and Z. Loddegesii^ the thin- 

 waUed cells are only occasional, while the other cells often show a considerable amount 



of thickening. 



In Z. Fischeri (text-fig. 19) and Z. Ottonis the walls throughout are 



fairly thin. Z. muricata has walls of intermediate thickness. The cells of the nerve- 

 courses of the lower epidermis are similar to those of the upper surface. In Z. cylin- 

 drica and Z. Lindeni the cells of the nerve-courses are fairly thick-walled, elongated 



