XXl] POLYPODIACEAE 377 



Adiantides antiquus (Ett.) (fig. 279, A) from the Carboniferous 

 limestone of Flintshire are portions of tripinnate fronds bearing 

 cuneate segments with numerous forked veins radiating from the 

 contracted base of the lamina. It is not improbable, in view of 

 Dr White's^ discovery of seeds on a very similar plant from the 

 Potts ville beds of North America, that this characteristic Lower 

 Carboniferous genus is a Pteridosperm. 



From Jurassic rocks in various parts of the world numerous 

 fossils have been described under the generic names Aspidium, 

 Asplenium, Davallia, Polypodium, and Pteris. In the great 

 majority of cases such records leave much to be desired from 

 the point of view of students who appreciate the dangers of 

 relying on external similarity between vegetative organs, and 

 on resemblances founded on obscure impressions of sori. The 

 generic term Woodwardites', which suggests affinity with the 

 recent genus Woodwardia, has been used for Rhaetic plants 

 belonging to the Dipteridinae. 



A plant described as Adiantides Lindsayoides from Jurassic 

 rocks of Victoria', characterised by marginal sori which appear 

 to be protected by the folded-over edge of the leaflets, and by 

 the resemblance of the pinnules to those of recent species of 

 Lindsaya, may be a true Polypodiaceous fern ; but in this case, 

 as in many similar instances, nothing is known of the structure 

 of the sporangia. Some sterile pinnae described by Yabe from 

 Jurassic rocks of Korea as Adiantites Sewardi^ may perhaps be 

 identical with the A ustralian species. 



In such a species as Polypodium Oregon ense Font., from 

 Jurassic rocks of Oregon, the generic name is chosen because 

 the " fructification seems near enough to that of Polypodium to 

 justify the placing of the plant in that genus'." But the fact 

 that no sporangia have been found is a fatal objection to this 

 identification. 



Onychiopsis. 

 This generic name was instituted by Yokoyama^ for a 



1 White (04). ^ Schenk (67) A. PL xm. ; Zeiller (03) p. 91, PI. xvii. 



3 Seward (04^) p. 162, PI. viii. fig. 5. « Yabe (05) p. 39, PI. i. figs. 1-8. 



» Fontaine, in Ward (05) p. 64. « Yokoyama (89), p. 26. 



