146 RECORDS OF THE AUSTRALIAN MUSEUM. 



and epidermis seems to be tolerably apparent, and the fact that 

 the fronds were supplied by a single vascular bundle, as in 

 Heterangiuni. * 



As regards the petioles a general resemblance exists between 

 those attached to our longitudinal section PL xxvii., fig. 12, and 

 that of Lyghiodendron given by Williamson and Scott,! but little 

 or no minute structure can be made out. They are here opposite, 

 and not spiral as in PI. xxvi., fig. 6 ; they are spiral in 

 Heterangium. t 



In conclusion, as to the general affinities of this very interesting 

 little plant the following observations may not be inappropriate. 

 Messrs. Williamson and Scott remark § — "The occurrence of 

 secondary thickening in a Fern-like plant is not in itself very 

 surprising. We know that it takes place in a perfectly typical 

 way, though not to any great extent in the stems of Botrychium 

 and Helmiiithostachys at the present day." Tlie same may be 

 justly claimed for the present plant. 



It is unnecessary to follow Messrs. Williamson and Scott through 

 their very interesting line of reasoning to show the structural 

 connection of Lyginodendron and Heterangium, with both Ferns 

 and Cycads, but the following sentence |j is probably very pertinent 

 to the Talbragar fossil — '■'■ The view of the affinities of Lygino- 

 dendron and Heterangium, which we desire to suggest, is, that 

 they are derivatives of an ancient and 'generalised' (or rather 

 non-specialised Fern-stock), which already show a marked diver- 

 gence in the Cycadean direction," and they think " the existence 

 of a fossil group on the borderland of Ferns and Cycadeaj is now 

 well established. "11 For this intermediate group of plants Dr. H. 

 Potonic has proposed ** the divisional name of Cycado-filices, a 

 class not hitherto recognised, Mr. Seward remarks to me, in the 

 Southern Hemisphere. 



I intended using the generic name of Pteroxylon for this plant, 

 but Mr. J. H. Maiden, Director of the Botanical Gardens, Sydney, 

 informs me that as Ptaeroxylon it was employed in 1835 for the 

 " Sneezewood" of South Africa. As, however, it is very desirable 

 to retain in the name a connection between the presence of 

 secondary wood and a Fern alliance I have adopted a suggestion 

 made to me V>y Mr. Whitelegge, and term it Bleclinoj:ylon.-\] Now, 

 although f:i\-7jXi'ov, is literally a "kind of fern," still, according to 

 Loudon it is also "one of the Greek names of the fern,"|| and may 



* Phil. Trans. (B) for 1895, clxxxvi., p. 754.. 



t Ibid., pi. 26, tig. 22. J Ibid., p. 756. 



§ Phil. Trans. (B) for 1895, clxxxvi., p. 766. 



il Ibid., p. 7(59. \\ Ibid., p. 770. 



** Lehrbuch der Pflanzenpalaeontologie, Hief 2, 1897, p. 160. 



tt fSXrixvov and ^uAor. 



IX Encyclopedia of Plants, 1880, p. 881, Note 2183. 



