CUTICLES OF CYCADEAN EEONDS. 



189 



tooth-like masses of thickening, but it can always be referred to the same general type 

 of wall-folding. We see the same tendency in Anomozamites . The lower epidermis 

 is composed of cells similar to those of the tipper epidermis, but of a somewhat larger 

 size ; their walls are thinner and may be sinuous or have the folds filled in, as just 

 mentioned. A few rounded hair- scars are present. The stomata are absent from the 

 nerve-courses and are irregularly scattered between [cf. PL 20. fig. 6) ; about 60-70 

 occur in each square millimetre. They have the same general form as previously 

 described, but are apparently rather more complex. Some of the examples from Marske 

 (PI. 19. fig. 12) do not difier greatly from the Anomozamites stomata except in the 

 proportions of thickening, the areas abutting immediately on the slit being the more 

 strongly thickened. The stomata in the Gristhorpe examples appear to have been 

 slightly sunken ; in most cases the pore is clearly seen and is surrounded by a strongly 

 thickened margin running to a point at either pole (PI. 19. fig. 11). The outer (upper) 

 thickening patches are often not so clearly defined as in the other genera, but have the 

 same relations to the auxiliary cells as those of Anomozamites. These outer patclies are 

 often thinner than the inner ones and occasionally appear to project into the centre, 

 almost above the slit (PL 19. fig. 10); they sometimes develop a small projectii 

 hump, similar to that seen in Ftilophyllum pecten and Bicfyozamites. Though it is very 

 difficult now to understand what the structures, which we see in the surface view, must 

 have meant in the solid, yet it is quite evident by comparison with the cuticles of other 

 groups, that Tceniopteris vittata possessed essentially the same epidermal and stomatal 

 characters as the other fronds in the Bennettitalean group, being especially like 



Anomozamites. 



When this is considered in addition to the facts quoted above, it seems that we have 



strong reasons for removing this species and its near allies from among the ferns and for 

 including it in the Bennettitales. 





TiENioPTERis MA J OH, Lindl. & Hutt. 



Some Tceniopteris fronds occur at Gristhorpe which are somewhat larger than those of 

 T. vittata, but are readily distinguishable by their distinct and widely separated dicho- 

 tomising veins, which are one millimetre apart or more and are very characteristic ; these 

 fronds are probably distinct from T. vittata, and may be referable to the form described 



by Lindley and Hut ton as T, major. 



In its cuticular characters it does not differ much from the species just described ; the 

 cells of the upper epidermis are rather large and have well-developed angularly folded 

 walls, slight additional thickenings being present on the tips. The lower epidermis has 



somewhat 

 fig. 9). 



scattered stomata which resemble very closely those of T. vittata (PI 



In this case the epidermal characters do not, so far as we have seen, present any 

 sharply marked features on which we can rely for the separation of the related forms 

 m<ijor and vittata. 



2r2 



