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XXIII.— On the Fossil Osmundacese. By R. Kidston, LL.D., F.RS. L. &E., F.G.S., 

 Foreign Mem. K. Mineral. G-esell. zu St Petersburg ; and D. T. Gwynne Vaughan, 

 M.A., F.L.S., Lecturer in Botany, Birkbeck College, London. (Plates I.-VIII.) 



(MS. received November 28, 1908. Read January 4, 1909. Issued separately January 23, 1909.) 



PART III.* 



We have already referred in the second part of this series to the opinions held by 

 various authors as to the systematic position of the genera Thamnopteris, Bathypteris, 

 and Anomorrhcea, and have given in detail the reasons that have induced us to adopt 

 these names for the specimens included in these genera (cf. Part II., p. 213). It is 

 therefore unnecessary for us to deal any further with the historical aspect of the matter 

 in the present communication, and we will at once proceed to the description of the 

 structure of the Fern stems in question. 



Thamnopteris, Brongniart. 



1849. Tableaux des genres de veget. foss., p. 35. 



Thamnopteris Schlechtendalii, Eichwald, sp. 



(Pis. I.-V.) 



1842. Anomopteris Schlechtendalii, Eichwald, Urroelt Russlamls, Heftii., St Petersburg, pp. 163-180, 

 pi. iv. figs. 3, 4, and 5.f 



1849. Thamnopteris Schlechtendalii, Brongt., Tableaux des genres des veget. Joss., pp. 35—36. 



1850. Splialmopteris Schlechtendalii, Unger, Genera et species, p. 195. 



1860. Sphallopteris Schlechtendalii, Eichwald, Lethxa Rossica, vol. i., p. 93, pi. iii. figs. 2 and 3, and 



pi. xx. figs. 2 and 5. J 

 1869. Thamnopteris ScldecJitendalii, Schimper, Traite de paleont. veget., vol. i., p. 701. 



A photograph sent to us by Mons. Zalessky, showing the external characters of the 

 type specimen, is figured half natural size in PI. II. fig. 2. The portion presented to 

 us for examination by Mons. Tschernyschew was cut from the upper part of this 

 specimen, and is figured natural size in PI. II. fig. 3. It comprised about two- 

 thirds of the total circumference of the complete specimen (cf. PI. I. fig. l), which 

 must have measured about 12 cm. across its greatest diameter. The exposed surface 

 of the fossil does not exhibit the true external surface of the original stock. It 



* Part I., Trans. Roy. Soc. Edin., vol. xlv., part iii. (No. 27), pp. 759-780, pis. i.-vi., 1907. Part II., idem, 

 vol. xlvi., part ii. (No. 9), pp. 213-232, pis. i.-iv., 1908. 



t The specimens figured came from the " gres cuivreux " of Kamskowatkinsk, government of Wjatka. 



\ The specimens figured came from the "gres cuivreux" of Bjelebei. 



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