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



Alethopteris sp. 



Locality : Preesgwyn. Horizon : Middle Coal-measures. 



Both surfaces are preserved, but could not be separated. As in 

 the two species already described, the cells over the vein-courses are 

 rectangular and elongated in the direction of the veins, those in the 

 intervening areas polygonal. 



The stomata can only be observed on one surface ; they are fairly 

 numerous, approximately eighteen to the square millimetre, and 

 arranged in rows parallel to and between the vein-courses as shown 

 on PL XXXI, Fig. 9. In structure the stomata are of the same type 

 as in Neuropteris heterophylla. The guard-cells can be clearly seen in 

 the stomatal cavity. The whole structure is similar to that described 

 by Professor Zeiller for Alethopteris grandini, except that in the present 

 case the guard-cells are also preserved. They are illustrated on 

 Plate XXXI, Fig. 10. 



Pecopteris sp. 



Locality: Preesgwyn. Horizon: Middle Coal-measures. 



Only one epidermal surface is preserved in this species. The cells 

 are polygonal except over the vein-courses, where they are rectangular 

 and elongated in tbe direction of the veins. No stomata have been 

 observed in the specimens examined. 



Cordaites sp. 



Locality: Preesgwyn. Horizon: Middle Coal-measures. Locality: 

 Old Hill, S. Staffs. Horizon : Upper Coal-measures. 



Preparations from several species have been made, all of which 

 show the same cuticular structure. The two surfaces are preserved, 

 but the one epidermis does not make good microscopic preparations ; 

 it shows, however, thin-walled cells and rows of stomata between the 

 vein-courses. The other surface is well preserved. The cells are 

 thick-walled, rectangular, and elongated in the direction of the vein- 

 courses ; those immediately above these being narrower and longer 

 than those in the intervening areas (see PI. XXXI, Fig. 11). There 

 are a few stomata on this surface ; they are oval in shape and arranged 

 in rows parallel to the venation. The stomata are smaller than in the 

 forms described above, and are frequently surrounded by four cells 

 which form a ring of thickening round the cavity (Text-fig. 4). 

 The guard-cells are lightly cuticularized and frequently imperfectly 

 preserved. Circular structures of unknown significance occur at 

 irregular intervals on the well-preserved surface (Text-fig. 5). 



Thalloid groivth. 



Locality : Old Hill. Horizon : Upper Coal-measures. 



A thalloid growth of uncertain affinity covers certain layers in the 

 Old Hill Marls. A typical piece is figured on PI. XXXI, Fig. 8. 

 At first sight it appears to be formed of cutin, but since it dissolves 

 in Schulze macerating solution it must be of a different chemical 

 composition. 



The fragments found measure as much as 10 mm. in length and 

 average 1"5 mm. in breadth. They branch dichotomously and 

 repeatedly. This fact, together with the lack of differentiation of 



