234 



CTENIS. 



cells, which are well preserved, and readily examined under the 

 microscope after suitable treatment, are characterized by prominent 

 circular papilla agreeing precisely with those figured as sori by 

 Raciborski and other authors. It is not uncommon among recent 

 plants to find the surface cells of a leaf provided with conical 

 elevations or papilla ; the circular elevations on the epidermal cells 

 of Ctenis (Text-fig. 43, A p and B) are identical with those met 

 with in recent plants. The enlarged drawing (Text-fig. 43) demon- 

 strates the nature of these sorus-like projections as seen in the 

 Ctenis segments in the Manchester Museum. The three epidermal 



FIG. 43. Ctenis, sp. Epidermal cells of the specimen shown in Fig. 42,. 



highly magnified. 

 A. Cells in surf ace -view ; B. side-view of the epidermal cells, showing 



the papilla). 

 p = papilla; ; s = stomata . 



cells shown in side-view in Text-fig. 43 B illustrates the nature of 

 the circular dots seen in surface-view in Fig. 43, p ; the shaded 

 areas in the drawing mark the position of depressions, which no 

 doubt occur immediately above stomata (Fig. 43, s). 



In view of these facts, I prefer to retain Ctenis as a Cycadean 

 genus characterized by pinnate fronds with linear segments 

 traversed by parallel veins connected at intervals by lateral 

 anastomoses. 



