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XVII. —On the Fossil Osmundacese. By R. Kidston, LL.D., F.R.S., F.G.S., 

 Foreign Mem. K. Mineral. Gessel. zu St Petersburg, Hon. Sec. R.S.E. ; and 

 D. T. Gwynne-Vaughan, M.A., F.L.S., Professor of Botany, Queen's University, 

 Belfast. (Plates I.-IV.) 



(MS. received December 20, 1909. Read December 20, 1909. Issued separately Marcb 24, 1910.) 



PART IV.* 



The fossils dealt with in this part of our memoir should have been included in the 

 first paper of the series had it been possible to treat the plants described in the order 

 of the complexity of their structure. Unfortunately, however, the specimens did not 

 reach our hands until Part I. was already published ; and since we were no longer able 

 to place them in their proper position in the sequence already embarked upon, it was 

 decided to defer their treatment until the conclusion of the memoir. 



Osmundites Kolbei, Seward. 



(Pis. I., II. ; and PI. III., figs. 19-21.) 



1907. Osmundites Kolbei, Seward, "Fossil Plants from South Africa," Geol. Mag., N.S., decade v., 

 vol. iv. p. 482, pi. xx. figs. 2-4, pi. xxi. figs. 5a-d. 



This species was founded by Professor A. C. Seward, on specimens discovered in 

 South Africa by Mr Kolbe in the Uitenhagen Series at Herbertsdale, Cape Colony. 

 Our thanks are especially due to Professor Seward for obtaining permission from 

 Mr Rogers, Curator of the South African Museum, to hand over the specimens to 

 us for microscopical investigation, thereby enabling us to render our account of 

 the fossil Osmundacese more complete. 



A full description of the external features of the fossil, illustrated by figures, has 

 already been published by Professor Seward, according to whom the plant must have 

 been a large one, for he states that the fragments he examined indicate a stem about 

 90 cm. long. The fossil has been subjected to much compression, and across its thickest 

 part it measured 20 cm. by 6. As seen in transverse section (fig. 1) it presents the 

 usual appearance of an Osmundaceous stock. The stem itself is comparatively narrow, 

 and is surrounded by a very thick mantle of concrescent and closely adpressed petiole 

 bases. When restored to its original uncompressed condition, the complete stock must 



* 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. Part III., idem, vol. xlvi., part iii. (No. 23), pp. 651-667, pis. i.-viii., 

 1909. 



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