CUTICLES OF CTCADEAN FRONDS. 



163 



The walls of all tlie epidermal cells are witliont tindulations, but are often slightly 



curved. In most of the cases examined, the lateral walls 



the outer walls) of both 



upper and lower epidermal cells are pitted in the same way as the lateral walls of Cycas 



This 



ery marked in E. Lehmcmni (PI. 18. fig. 10 



also fi 



In E. Woodii 



and on the lower surface of -S. villosus pittings are infrequent. In the examined species 

 of, Bncephalartos the inner and lateral walls of the epidermal cells are 



often 



slightly 



Fiff. 4. 



Fig. 5. 



cephalartos Woodii. — Upper cuticle in surface view, 

 showing form and arrangement of epidermal cells. 



X 4.50. 



E. Lehmanni. — Upper cuticle in surface view 



X 450. 



thicker than the outer walls (PI 



fig. 10) 



Towards the pinna-margins the cells 



become smaller and thicker-walled. In some cases, as in U. horridm and E. villosus 

 (PL 18. fig. 11), the elongated epidermal cells are septate. 



Stomata are confined to the lower surface of the pinna;, and more or less definitely to 

 the areas between the nerve-courses. Their longitudinal axis is typically coincident with 

 that of the pinna. They are in most cases considerably sunk below the geneml level of 



pidermis without overarching of the subsidiary 



that the outer air-spa 



fairly long and narrow and tubular in shape (text-fig. 6). There is a somewhat irregular 

 system o/intercalated cells separating the guard-cells from the general epidermal cells. 

 In median sections of the stomata, typically two intercalated cell-series appear (text-fig. 6) ; 

 the sections may not, however, pass through a cell of both series. Nestler (1895, p. 348) 

 mentions that one or two intercalated series are present ; while according to Kraus (1866, 

 p. 34) the o-uard-cells lie immediately under the epidermis except at the pinna-bases. 

 The stoma-opening is somewhat elongated and elliptical to (luadrangular in shape (text- 



^ Q n 



SECOJsD SERIES.— BOTANT, VOL. VIII. 



C 



