168 



MK. H. HAMSHAW THOMAS AND MISS N. BANCEOFT OK 



The six species examined show agreement in the occurrence of thick-walled and thin 



walled epidermal cells. They fall 

 ment of the cells. M. Macleayi { 



two 



oups, however, accord in f]^ to the 



spiralis ?), M. Denisonii (text-fig. 13), and M. Hopei 



(text-fi 



differ from the other three species in the 



ularly-shaped three- or 



the long axis of the 



pinna 



In 



four-angnlar cells placed transversely or obliquely to 



this first group, moreover, the thick-walled cells are very marked, their cavities bein 



often almost filled up ; there is also a heavy primary wall, particularlv in M. Denisonii 



b 



t-fi 





13) 



I 



Jf. 



llip 



M. 



"ylindrica (PI. 18. fi 



and M. 



spti 



Fraseri ?) the cells are three- or more often four-angular ; they are generally elongated 

 the direction of the longitudinal axis of the pinna, though the thinner-walled cells 

 } often squarish. In this second group, the walls are often much pitted, particularly 

 the case of the thin-walled cells (PL 18. fig. 15). In the other type pitting is less 



Fig. 14. 



Fig. 13. 



r 



Ifacrozamia Denisonii. — Upper cuticle in surface view 

 showing thin-walled and thick-walled cells, and 



V 



the heavy primary cell- walls. Note the irregular 

 arrangement of the cells, x 450, 



if. Ho])ei. — Upper cuticle in surface view, showing 

 thin-walled and thick-walled cells, and pitting of 

 the thin-walled cells, x 450. 



evident 



Layering of the 



cellulose is frequently marked, as in M. cylindrica (PI 



fig. 15). The cells of the upper surface and of the nerve-courses of the lower surface 



similar in both groups, but th 



between the nerve-courses are usually 



shape and size, and are much more uniformly thickened (text-figs. 15 & 16), although 



'cillip 



the elongated 



occasionally thin-walled cells occur. Sometimes, as in M. co: 

 thickened cells are septate. 



Stomata occur only on the lower surface between the nerve-courses ; their long axis 

 is parallel with or slightly oblique to the long axis of the pinna. A regular longitudinal 



arrangement, almost in 



seen in M. spiralis 



Fr 



Sive sunk below the epidermis 



apparently rather 



'). In all cases the 

 ular system of cells 



