68 



GYMNOGRAMMOID FERNS 



[CH. 



sori are connected marginally by vascular commissures. The result may 

 appear similar to what is seen in Pteris, Lindsay a, Diellia, or Nephrolepis. 

 But the innovation of a connecting commissure may be held as homoplastic 

 in them all, rather than as an evidence of kinship. It ranks in the propagative 

 region with the adoption of a reticulate venation in the sterile: and this 

 innovation is seen to arise independently in various groups of Ferns quite 

 distinct from one another systematically. 



A more important point is the existence as far back as the Wealden of 

 fossils referred to the genus Onychiopsis, in regions as far apart as Britain, 

 Germany, Japan, and South Africa (Seward, Fossil Plants, Vol. ii, p. 377). If 



Fig. 627. Sporangia of Cryptogramme crispa, showing instability in the obliquity ot the 

 annulus, in its induration, and in the structure of the stalk. 



the reference to this affinity be correct, the early occurrence of a Fern so 

 close in kinship to Cryptogramme would enhance the interest which the 

 indications of antiquity seen in the living representatives of that genus 

 already possess. 



Jamesonia Hook, and Grev. 



Jamesonia is a genus comprising some 14 species: they live in the higher 

 Andes, and are characterised by a reduced habit, but particularly by a 

 continued apical growth of the simply pinnate leaves: they live on exposed 

 boggy ground together with Sphagnum. The genus has usually been grouped 

 systematically with Gymnogramme, from which it is distinguished by habit. 

 This is excellently shown by Karsten's drawings (Fig. 628). The thin creeping 



