234 METAXYOID FERNS [CH. 



have a four-rowed stalk, and a slightly oblique annulus. Such characters 

 ensure for it an archaic position. 



The old genera Syngramme and ElapJioglossnm appear to be related to 

 Metaxya by similar primitive features: but in the latter the circumscribed 

 sorus is replaced by an Acrostichoid state, such as has been found to be 

 derivative in several other phyletic lines. In particular a parallel may be 

 traced in this respect with the Dipteroid Ferns described in the preceding 

 Chapter. But the venation marks off the Metaxyoid Ferns from these: for 

 here it is simply pinnate, either without any vein-fusions as in Metaxya 

 itself, or, where fusions occur and areolae are formed, there are no free 

 vein-endings within them. This is in fact the most obvious character which 

 defines the Metaxyoid series from the Dipteroid Ferns. 



Syngramme J. Smith (1845) 



This genus includes about 16 species of rare and local Ferns from the 

 Malayan region. They have mostly a short and creeping rhizome, bearing 

 bristle-like hairs (5. vittaefonnis); but sometimes the bases of the hairs 

 may be widened into small scales bearing a terminal bristle {S. quinata 

 (Hk.) Carr). The leaves are stalked and often coriaceous: in most species 

 the blade is undivided, but 5. quinata bears three to five long pinnae, one of 

 which is terminal. These pinnae are lanceolate, about \\ inches wide, with 

 pinnate venation, but showing irregular marginal fusions: except for this 

 last, and their entire margin, these pinnae resemble those of Metaxya 

 (Hooker, Sp. Fil. Vol. V, Plate CCXCVil). It is the same with the simple- 

 leaved S. borneensis (Hk.) J. Sm., except that here the marginal fusions are in- 

 constant, the veins being free towards the base of the blade, where numerous 

 free endings occur (Fig. 735,^, <^). In other species the fusions may be more 

 numerous, so as to constitute a marginal reticulum, as in 5. alsinifolia (Pr.) 

 J. Sm. (Fig. 735, c,d): but it is irregular, and may show free marginal twigs 

 mixed with closed loops. Such facts suggest a relatively recent progression 

 from an open Pecopterid venation, and it is noteworthy that there are no 

 intra-areolar vascular twigs with free endings, as in the Dipteroid Ferns. 



Observations on herbarium material show that, as in Metaxya, the rhizome 

 s solenostelic in S. borneensis and alsinifolia : but three separate strands 

 have been seen in the basal region of the petiole, which thus shows a 

 structural advance on the condition of Metaxya. The sori follow the veins, 

 but stop short of the leaf-margin. If a string of sori extended along one vein 

 of Metaxya were linked together, the result would be what is seen in Syn- 

 gramme. In both genera the sporangia, which are accompanied by paraphyses, 

 have a slightly oblique annulus interrupted at the stalk, and the spores are 

 tetrahedral. But in Syngramme the stalk is three-rowed, while in Metaxya 



