﻿1851.] BUNBURY — FOSSTL PLANTS OF SCARBOROUGH. 181 



species, as represented by him, well agrees with that which is common 

 in the recent Hymenophylla, while their reniform or transversely 

 oblong shape, in ours, is more characteristic of Bicksonia. To that 

 genus, I think it clear that our plant is allied, although in its techni- 

 cal characters there is nothing to exclude it from the Hymenophyl- 

 lites of Goeppert. The texture of the frond is almost too vague and 

 uncertain, in a fossil state, to afford good generic characters ; besides, 

 there is no proof that the texture of this Sphenopteris was more 

 membranous than that of Bicksonia punctiloba* for instance ; and 

 the distribution of the veins, one veinlet running into each ultimate 

 lobe or segment, is the same in many Bicksonice. If the fructifica- 

 tion were not so very rare, it might doubtless afford good characters 

 for subdividing the genus Sphenopteris, which evidently includes 

 types allied to several very distinct recent genera. But as it is, it 

 appears to me that there is more practical convenience, for the pre- 

 sent, in leaving this genus, however miscellaneous, united under the 

 name and character originally assigned to it by Brongniart. 



The Balantites Martii, Goepp., from the coal-formation of Silesia, 

 is evidently allied to the genus Bicksonia as understood by Hooker, 

 but to a different group of species from that to which I have com- 

 pared our plant ; and in the form and division of its frond, it comes 

 nearer to Pecopteris than to Sphenopteris. 



Another and a very interesting fossil plant which I may here men- 

 tion, as having in all probability belonged to the same tribe of Ferns, 

 is the Tympanophora racemosa of the 8 Fossil Flora,' figured in that 

 work from such imperfect materials, that its affinities appeared alto 

 gether doubtful. The splendid specimens in Mr. Bean's collection 

 show clearly that it was the fertile state of a Fern, having, like the 

 BicksonetB and Hymenophyllece, its fructification contained in termi- 

 nal cup-shaped indusia. Mr. Bean's best specimen shows a very 

 considerable portion of the frond, which is regularly tripinnate, and 

 has thoroughly the aspect of a Fern : the main stalk rather thick, 

 firm, and rigid ; the subdivisions slender and delicate, with no distinct 

 leafy border or expansion ; the frond being, as in some recent Ferns, 

 reduced to the mere skeleton or framework of veins. It has thus, 

 as Brongniart remarks f, an evident analogy with the Thyrsopteris 

 elegansX, a very remarkable recent Fern from Juan Fernandez, in 

 which the fertile part of the frond has no parenchyma, consisting 

 solely of the ribs or skeleton of the tripinnatifid leaf, with the cup- 

 like indusia terminating its ultimate divisions. It is very interesting 

 to find these rare and singular types of structure common to two 

 geological periods so widely separated. 



The Thyrsopteris has fertile and barren branches on the same 

 frond. In those specimens of the Tympanophora which I examined, 

 there was no appearance of any barren leaflets, nor of one part of the 

 frond being different from the rest ; but Mr. Bean, whose long study 

 and close observation of the Scarborough fossils give great weight to 

 his opinions, thinks that the Pecopteris Murrayana, Brongn., is the 



* Hooker, Sp. Fil. vol. i. p. 79. f Tableau des Genres, p. 26. 



% Hooker, Gen. Fil. t. 44 A. 



