CUTICLES OF CTCADEAN FEONDS. 



185 



the same characteristic thickenings as previously descrihed ; the crescentic patches are 

 terminated in sharp points {cf. text-fig. 31) and partially cover the ventral patches, 

 while the central space on either side of the slit is thinner. The small projection 

 from the centre of the crescentic patch which is charact(n'istically seen in Ptilophyllv/ni 

 pecten, DietyozamiteSj etc., is here apparently ahsent. 



A large frond from Marske with a form somewhat like that of Zamites gig as yielded, 

 after some difficulty, a cuticular preparation of the upper epidermis, in which the cells 

 are rounded in shape and quite distinct from the other examples in the present group. 



Zamites (?) sp. Scale-leaves from stem. 



In the Natural History Museum (Palseohotanical Department) of Stockholm, there 

 is an interesting specimen, collected at Whitby by Prof. Nathorst in 1909. It appears 

 to be the remains of a branching stem about 5 cm. wide ; one part of it is fairly well 

 preserved, and seems as if covered with numerous overlapping scales or leaves ; it is 



Fig. 31 



Stoma of Zamites gigas, Lindl. & Hutt., showing form of the thickening on the upper side of the guard-cells. 

 The circle surrounding the stoma represents the outline of the shallow pit in which the stoma was sunk. 



ewhat similar to those of the James Yates Collection, figured by Wicland (1911 



fiirs 



The scale-leaves appear as if lanceolate in shape, of rather thick texture, and striated; 

 they are very indistinctly outlined. They yield, however, cuticular preparations which 

 show a certain amount of structure, though considerably obscured by a mass of hypo- 

 dermal or other tissue, which was evidently thick- walled and has resisted both decay 

 and maceration. The actual epidermal cells are not clearly seen, but some of the 

 stomata are quite visible; they appear to be similar "in both form and arrangement 

 to those previously described (see PI. 19. fig. 2). 



