174 



SCHIZAEACEAE [CH. 



The living genus which presents on the whole the most archaic features 

 is Lygodium, with its protostelic axis, and its large sporangia with ill-defined 

 annulus sometimes irregularly doubled, and its relatively large spore-output 

 from each. But its leaf is highly elaborated and specialised for climbing, 

 and it occasionally shows reticulate venation. The protection of the 

 sporangia by elaborate indusial growths is doubtless in accord with their 

 exposure at the heights to which the sporophylls climb in the forest. It has 

 been noted above that the output of sperms from each antheridium is 

 large. 



Schizaea, on the other hand, has more primitive leaves, with prevalent 

 equal dichotomy and constantly open venation. The stelar structure shows 

 irregular but incomplete advances from the simple protostele, while the 

 sporangia without highly specialised protection have a more perfect annulus, 

 with a diminished output of spores. The gametophyte of Schizaea is, how- 

 ever, unique in its simplicity, and the output of sperms from each antheridium 

 is small. 



Aneinia is distinctly more advanced in the general features of the 

 sporophyte. Its radial construction accords with the dictyostelic skeleton 

 of most of the species, and is led up to by the solenostelic \Aneniiorrhiza. 

 The leaf is pronouncedly dichopodial, closely resembling that of Osmunda 

 or Botrychium in its younger stages, but occasionally progressing to reticu- 

 lation. The sporangia are relatively small and with lower spore-output, but 

 with specialised annulus and enlarged distal face. The output of sperms 

 from the antheridium is relatively low (Kny, Berlin, 1869). The effect of 

 these features is to place Anemia in a position of advance. 



This position is shared by Mohria, which also has a dictyostelic axis with 

 highly dichopodial leaves. The sporangia, however, each with its indusial 

 protection, have a less specialised annulus, but a low spore-output. The 

 dermal protection is by scales in place of the simple hairs which are seen in 

 the rest of the Family. 



It is plain that the characters thus summarised do not run parallel : it is 

 therefore difficult to seriate the genera according to them, so as to bring out 

 any single probable line of descent. Taking them cumulatively, however, it 

 may be held that Lygodium is on the whole a relatively primitive type, though 

 curiously specialised in accordance with its climbing habit: while Mohria 

 is a relatively advanced type, with specialisation in relation to dry conditions: 

 and this conclusion is supported by the detailed, almost trivial-seeming 

 structural fact that in Anemia and Mohria the cap-cell of the antheridial 

 wall is undivided after the Leptosporangiate type, while in Lygodium it is 

 divided, and the output of sperms is large, thus conforming to what is seen 

 in more primitive Ferns. A rough sequence of the living genera may then 

 be given thus : 



