332 Hejjorts and Proceedings — 



nervosa, Brongt. ; and Pec. muricata, Schlotli. sp., tlie genus Mario- 

 pteris,^ which though founded on characters observed on barren 

 fronds, brought together certain species apparently closely related 

 and which stand between Pecopteris and Sphenopteris. Brongniart 

 himself proposed in MS. the genus Heteropteris for this group, but 

 his name has since been appropriated. 



One of the chief characters of Mariopteris is taken from the bifurca- 

 tion of the rachis of the primary pinn^, each foi'k of which bifurcates 

 a second time, these last bifurcations supporting the foliage- bearing 

 •tertiary pinnee. Stur, on the other hand, regards the frond as once 

 bifurcating or sometimes forming a double bifurcation, as has been 

 figured by Zeiller,- 



The main point of difierence between these two authors lies in 

 Stur regarding as a frond what Zeiller regards as a pinna ; con- 

 sequently, what is looked upon as a rhizome or stem by Stur, is 

 regarded as the main axis of the frond by Zeiller. 



From our own experience of this group of ferns, Stur's view of 

 their structure- seems to go against the evidence he has adduced in 

 its support. Zeiller, in proof of his views, gives a very good figure 

 of Mertensia glaiicescens, Willd.,^ where are shown, springing from 

 the main rachis, similarly formed pinn^ to those which occur in 

 Mariopteris. We believe Zeiller's interpretation of the structure of 

 the ferns in question to be correct and his genus Mariopteris of real 

 practical value, whereas, Stur's Diplothmema, as again employed by 

 him, is little more than another name for Sphenopteris, Brongt. 



He only describes one specimen in fruit, Diplothmema cf. 

 Zioickauiense, Gutbier sp., which scarcely aifords enough evidence 

 from which to form any opinion of the affinities of the fern. He 

 also figures a bifurcating '\fertiles Phylloin " of Diplolhnema stib- 

 geniculatum, Stur; hence there are in his Diplothmema two modes of 

 increase. 



Although there are some points, in which we cannot agree with 

 Dr. Stur, his communication deserves the careful study of all those 

 interested in Fossil Botany, as it contains an amount of valuable 

 information regarding the fructification of Carboniferous Fossil 

 Ferns now for the first time brought together in book form. The 

 value of his paper is much enhanced by the addition of forty-four 

 beautifully executed woodcuts. 



K/Si^os-TS -^n^iD I^I^OG:H]:EX)Il^rG-s. 



Geological Society of London. 

 I.— May 14th, 1884 {continued). 

 Prof. T. G. Bonney, D.Sc, F.R.S., President, in the Chair. 

 2. " Note on a Specimen of Iron Amianthus." By the Eev. J. 

 Magens Mello, M.A., F.G.S. 



The accompanying specimen was found at the bottom of one of 



^ Bui. Soc. geol. de France, 3^ ser. vol. vii. p. 93. 



^ Bui. Soc. geol. de France, loc. cit. pi. v.-vi. 



3 Ann. des bcienc. jS'at, 6^ serie. Bot., vol. xvi. pi. xi. f. 1. 



