XXVIl] THINNFELDIA 543 



Jurassic, Cretaceous and some Tertiary species referred to 

 Thinnfeldia, but many of these are probably not generically 

 identical with T. odontopteroides or T. rhomboidalis. Mr Berry^ 

 in a paper on The American species referred to Thinnfeldia 

 concludes that the genus is "a rather indefinite one... and 

 badly in need of revision." He regards the Middle and Upper 

 Cretaceous American species as Conifers related to Phyllocladus 

 and probably forming a link between the Podocarpeae and 

 Taxeae : for these forms he proposes the generic name Proto- 

 phyllocladus. The opinion has been expressed elsewhere' that 

 this "problematical*" genus rests on an unsatisfactory basis; 

 the available data do not justify the use of a name which 

 implies the existence in North American Cretaceous floras of 

 a type related to the New Zealand and Tasmanian Conifer 

 Phyllocladus. We are not' in a position to assign a single 

 species of Thinnfeldia to the Filicales or the Gymnosperms. 



A leaflet from Jurassic rocks of Poland figured by Raci- 

 borski* shows what this author regards as the impression of a 

 circular sorus : no sporangia have been found. A specimen 

 in the British Museum ^ which is said to come from Rhaetic 

 beds in Queensland, shows a row of contiguous polygonal 

 prominences on each side of the midrib which resemble the 

 sori of a fern; but until sporangia are discovered we cannot 

 determine the precise nature of this apparently fertile frond. 



A species described by Fontaine" from the Potomac beds 

 (Wealden- Jurassic) of North America as Thinnfeldia variabilis 

 affords a good example of a plant which cannot be identified 

 with any degree of confidence either as a fern or a seed-bearing 

 type. Mr Berry draws attention to the former application of 

 this name by Velenovsky to a distinct Lower Cretaceous 

 Bohemian species and proposes for Fontaine's plant the name 

 T. Fontainei ; he maintains that no one has doubted the fern- 

 nature of the Potomac plant. T. variabilis may indeed be a 

 fei'n, but the evidence is not such as to preclude legitimate 

 doubts as to the correctness of this suggestion. Solms-Laubach', 



1 Berry (03). = Seward (04) p. 31. » Hollick and Jeffrey (09) p. 2i. 



" Baciborski (94) A. PI. xx. figs. 1, 2 ; Zeiller (OO''') p. 98. 

 5 V. 5950. « Fontaine (89) Pis. xvii. xviii. 



'' Solms-Laubach (91) A. p. 141. 



