200 THE Lire History OF 
rectly external to the bundles, while these formations occur more 
abundantly on leaves developing later yet they are rarely over a 
bundle ( f. 99). 
Leaves formed from the rhizome at a later stage of growth 
show a variation in form from oblanceolate to linear ) 94, 95). 
Such leaves have a vein extending through the middle and one 
along each margin with numerous anastomosing branches. Glands 
and scales are somewhat more numerous and the epidermis con- 
tains but little chlorophyl. 
The latest leaves formed show the greatest length and are 
ridged over the nerves on the upper surface, bearing scales between 
the central and marginal veins (f. 709). These scales, while no 
more numerous on the upper surface than on the lower, are fre- 
quently larger, measuring as much as 1.9 mm. in length. It is 
found that the regularity of arrangement of the stomata and the 
increase of the ridges of the leaves increases as a form approxi- 
mate to that of the adult is reached ( f. 704). 
SPOROPHYLLS.— The sporophylls are long linear coriaceous 
leaves with a short petiole exhibiting the epinastic growth of so 
many ferns. The numerous scales which doubtless serve as a 
protection to the unrolling leaves persist in mature forms (f. 709- 
III) The dorsal surface is marked by two deep grooves imme- 
diately external to the lateral veins, and these grooves contain the 
stomata, glands, sporangia and accompanying paraphyses ( f. 104- 
709). The two fascicles of stelar elements given off from the 
edges of the incomplete cylinder in the foliar gap in the rhizome do 
not fuse until some distance in the petiole has been traversed, and 
the lateral branches are given off before the fusion is complete 
(f. 102, 103, 1, 6, 7). The lateral veins and the central vein are 
connected by various anastomosing branches (f. 102-100). The 
central vein runs quite to the apex of the leaf (f. 94-95), while 
the lateral veins end free a short distance below the tip or termi- 
nate in an anastomosing branch (f. 103-109). The vascular ele- 
ments of the leaves are the same as the rhizome in composition, 
and the bundles are enclosed in a sheath of two to six layers of cells 
iin SR walls ) 108d, f). The mesophyll of the upper 
anions peius closely packed and contains a large amount of 
; giving this surface a dark green color (f. 774). The 
