ANATOMY AND AFFINITY OF CERTAIN RARE AND PRIMITIVE FERNS. 367 
Leaf— The typical leaf is about 1 foot long. It is slender, simply-pinnate, and 
unbranched, and shows a continued apical growth. Reduction forms are not 
uncommon. In our plants the rachis of these small leaves may not exceed \\ inches 
in length ; the pinnae are few and typically malformed, and scattered irregularly 
Text-fig. 3. 
along the rachis. The distribution of these small leaves is variable, but the majority 
of them are formed towards the end of the season’s growth and receive their traces 
from ventral leaf-gaps. The condition thus shown seems similar to that which I 
have demonstrated in Platyzoma, R. Br. (Trans. Roy. Soc. Edin., vol. li, pt. iii, 
1916). In both these plants the axis is slow-growing, and the small leaves seem 
expressive of xerophytic conditions. 
Text-fig. 4. 
Within the genus there is considerable variation in the details of pinna-form and 
venation. The smallest pinnae are found in J. scalaris (text-fig. 3), the largest in 
J. verticalis (text-fig. 4). In the latter species the pinnse are sessile, but in J. scalaris, 
J. cinnamomea, and J. canescens they are stalked (text-figs. 3, 5, 6). The pinnse of 
J. cinnamomea and J. verticalis are thick and leathery , but those of J . canescens 
and J. scalaris are more delicate. The pinna-margin is membranous, and indexed 
