4 i 8 STUDIES IN FOSSIL BOTANY 



similar species of Sphenopteris. This identification was, 

 in the first instance, due to the penetration of Mr. R. 

 Kidston, 1 who has further pointed out to me that at 

 least two other Lower Carboniferous fronds, 5. Linkii 

 (Gopp.) and 5. dissecta, Brongn., also show characters 

 identifying them with Heterangium, of which there 

 must clearly have been several species in this Flora. 



We have therefore to picture Heterangium Grievii 

 to ourselves as a Fern-like plant, with a long, upright, 

 or perhaps trailing, ribbed stem, bearing large and 

 graceful, finely divided fronds, much resembling those 

 of some recent Asplenium? 



III. Affinities of Lyginodendreae 



At present we have no certain knowledge of the 

 fructification of Heterangium ; the various species of 

 Sphenopteris which no doubt represent the foliage of 

 the genus have so far only been found in the sterile 

 condition. Associated with Heterangium Grievii in 

 the Burntisland petrifactions are seeds [Conostoma ovale 

 and C. intermedium), described by Williamson in i876, s 

 which are evidently very nearly allied to Lagenostoma, 

 as shown by the structure of the testa and pollen- 

 chamber. It is very probable that they may have 

 belonged to Heterangium, but there is as yet no direct 

 evidence. As has been shown above, the agreement 



1 Kidston, "Fructification and Internal Structure of Carboniferous 

 Ferns," Trans. Geol. Soc. Glasgow, 1889, p. 49. 



2 When first discovered, the present Sphenopteris elegans was identified 

 with Fumaria officinalis, which is thus a synonym for Heterangium Grievii, 

 certainly a strange freak of nomenclature ! 



3 "Organisation of Fossil Plants of Coal-measures," Part viii., Phil. 

 Trans. Hoy. Soc. vol. 167, p. 243, Figs. 80-87. 



