386 L. Wills — Plant Cuticles, Coal-measures. 



Schiilze's macerating fluid, and then washed in ammonia. The 

 bleached cuticle alone remains after this treatment. The two surfaces 

 of the leaf when present were separated by careful teazing with 

 needles. The preparations were stained with either Bismarck brown 

 or diamant fuschin. 



3. Desckipxion. 



Neuropteris heterophylla, Brongn. 



Localities : Preesgwyn and near Cefn. Horizon : Middle Coal- 

 measures. 



The general form and venation of the leaflets are indicated in 

 PI. XXX, Fig. 1. Under the microscope the leaflets show two 

 distinct types of cuticular structure ; both types possess the following 

 common features. The cells of both the upper and lower epidermis 

 are roughly polygonal in outline, except over the vein-courses, where 

 they are rectangular and elongated in the direction of the venation. 

 The cell-walls are of a normal thickness and straight. On one 

 surface the stomata are fairly numerous, approximately sixty-eight to 

 the square millimetre, while on the other there are only a few scattered 

 ones. On both surfaces they are restricted to the areas between the 

 vein-courses. 



The stomata (PI. XXX, Figs. 2, 3, 4, 5, S) are irregularly arranged. 

 Each individual one (Text-fig. 1) is nearly spherical in shape. The 

 guard-cells are slightly sunk, lightly cuticularized, and sometimes 

 imperfectly preserved. The cells surrounding the stomatal cavity, 

 generally five or six in number, are similar to the other epidermal 

 cells, but take a deeper stain ; where they abut on to the stomatal 

 cavity they form a solid ring of thickening (PI. XXX, Fig. 4). 



The distinguishing feature between the two types is the presence 

 of small papillate hairs on one surface of the leaf in type ^ and their 

 absence in type a. As there are corresponding types of Cyclopteris 

 leaflets ( Cyclopteris is a name given to one type oi Neuropteris foliage), 

 it would seem possible that two distinct species of Neuropteris are 

 here represented. Further, in a few specimens of type a a marginal 

 zone of water-stomata occurs (PI. XXX, Pig. 2, 7F), This is of interest, 

 as the same structure is found in the corresponding Cyclopteris type 

 (PL XXXI, Fig. 7) and in some modern forms. ^ These stomata are 

 similar in structure to the ordinary air-stomata but larger, more 

 circular in outline, and with a less prominent ring of thickening round 

 the stomatal cavity (PI. XXX, Fig. 2 ; PI. XXXI, Fig. 7). Certain 

 of these stomata have a thin walled tissue in the stomatal cavity in 

 place of the normal two guard-cells. 



In addition to the two types described two specimens show 

 glandular patches on certain cells of the single surface preserved 

 (PL XXX, Fig. 5). These glandular cells, like the hairs in type /3, are 

 irregularly scattered over the whole leaf surface. No water-stomata 

 have been observed in this type. 



Leaflets of a Neuropteris have been collected from the Old Hill 

 Marls, but have not yet been identified. 



^ G. Haberlaudt, Physiologische Pflanzenanatomie, 1909, p. 449. 



