IS 76.] Knowledge of tie Fossil Flora in India. 3G9 



The secondary veins pass out from the rhachis at a very acute angle 

 pretty straight towards the margin, where they are incurved. In the 

 apical portion, where is no midrib, the secondary veins radiate fan-wise. 

 The secondary veins are alternately single and forked ; the furcation 

 occurs at different parts of the length of the veins, all of which are 

 regularly equally distant from one another. I cannot observe any distinct 

 peduncle ; the leaf becomes more attenuate towards the base and the rhachis 

 thicker, until at last only the latter remains. 



It seems certain that the aggregation of the leaves is not due to an 

 insertion on a common stalk, but rather to associated growth out from 

 the rhizome. As I have said, this form has no analogue in any existing 

 fern except Yittaria, where also the rhachis vanishes towards the apex 

 and the secondary veins pass out at a very acute angle from it ; the only 

 difference being that our fern has many more secondary veins, and that 

 the frond in proportion to its length is much broader. I have obtained 

 from Mr. Kurz a good collection of Indian Vittariae for comparison, 

 and of these the Vittaria intermedia from Java comes nearest to ours. 

 But amongst the American forms are some still broader ones, which would 

 come still nearer. 



Amongst fossils nothing is as yet known at all like our fossil plant. 



If we take the single leaf and consider only its shape and the general 

 disposition of the veins, then we find an approximate similarity in Sagenop- 

 teris, but here the leaves come out from a common stalk and the secondary 

 veins anastomose so as to form a net-venation. 



Amongst the Taeniopterides we find scarcely any similarity, as all these 

 have a rhachis continuous to the apex of the frond, and the angle at which 

 the secondary veins pass out from it, as for instance in Taeniopteris Iforrisi, 

 Oldh.,* or in Phyllopteris plumula, Sap.,f far less acute than in oixr fossil. 



IV.— DICTYOPTERIDES. 



This order includes all ferns with net- venation. This is again only 

 a palseontological order, for in the same living genera are forms with 

 forked, as well as with netted veins, for instance, in Fteris, Asplenium, etc. 



But there is yet a peculiarity : it is that most of the ferns with 

 net-venation occur in the mezozoic epoch, without any corresponding forms 

 with free veins, while in the palaeozoic epoch the ferns with net -venation 

 are very rare, those with free veins predominating. In the palaeozoic we 

 have mostly only Lonchopteris, Bgt., which has its analogy in Alethopteris, 

 and Dictyopteris with complete analogy in Ncuropteris ; so that the order 

 Dictyopterides (eae) can very fairly be considered to be a mezozoic one. 



* Oldham and Morris, Bajmahal Flora, Pal. Indica, 1862, PI. Ill, f. 1. 

 f Saporta, Veget. foss. de France (Paloeont. Franchise), PL LXIII, f. 6. 



