18i ME. H. HAMSHAW THOMAS AND MISS N. EANCEOFT ON 



do not differ markedly from those on some modern Cycad fronds, but they are not so 

 massiye as in the present example, nor are they arranged in such 

 When, however, the epidermal cells are arranged in reo-ular rows, 



a regular sequence, 

 the outgrowths from 



them may be expected to possess the regular arrangement which we see here. The 

 fronds just mentioned appear to possess stomata which are somewhat similar to those 

 above described (see text-fig. 30). 



An interesting comparison can be drawn between the hair-scars seen so abundantly on 

 these fronds, and the hairs on the bracts and lower part of the strobilar-axis in the 

 flower of WilUamsonia scotica, recently described from the Kinimeridge of Sutherland 

 by Prof. Seward *. The hairs in the latter formed a very striking feature ; they were 

 YQYj numerous, and arose from the thickly cuticularised outer wall of an epidermal cell 

 which formed a dark ring round the lower end of the hair. Higher up the walls of the 

 hair were much thinner. If leaves bearing hairs of this type had been preserved 

 as impressions in the same way as the material now before us, we could scarcely expect 

 the substance of the hair to be preserved, though the cuticularised base would remain as 



Tm. 30. 



Stomata ot PtilopIijiUum sp., sliowing form of the guard-cell thickenings. 



a clearly visible ring on the outside of the epidermis. It is possible, too, that hairs of 

 tliis type might have been deciduous. The occurrence of these characteristic hair-scars 

 forms another link connecting the Ftilophyllum fronds with the type of inflorescence 

 now^ known under the o^eneric name of WilUamsonia. 



Zamites (Williamsonia) gigas, Lindl. & Hutt. 



There have yet been found few examples of this species from which good cuticular 

 preparations can be made. One specimen, however, from Marske, which has large 

 pinnae and apparently belongs to this species, yields preparations which show the cells 

 of the upper epidermis fairly clearly. The lower epidermis is somewhat crumpled, and 

 the preparations made from it are always rather dirty ; its cells are very indistinct, and 

 the pits in which the stomata appear to have been sunk are usually filled with matrix. 

 We can, however, make out some of its epidermal characters. The upper epidermis is 

 thinly cuticularised, and is composed of cells of the iisual type with very sinuous out- 

 lines. The lower cuticle is also very thin, and the outlines of the cells cannot be seen. 

 The stomata are arranged in fairly regular rows with their axes at right angles to the 

 rows ; the guard-cells appear to be considerably sunken and are surrounded by a brown, 

 rather highly cuticularised area, probably the walls of the pit. The guard-cells possess 



* Seward (191 1^, p. lOS, pi. 12. figs. 40-42 & 45. 



