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 
Heterangium .* 
As regards the petioles a general resemblance exists between 
those attached to our longitudinal section PL xxvii., fig. 12, and 
that of Lyginodendron given by Williamson and Scott, f 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. J 
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 auy great extent in the stems of Botrychium 
and Helminthostachys at the present day.” The 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 || 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 1 generalised > (or rather 
lion-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 Cycadese is now 
well established.”^! 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 by Mr. Whitelegge, and term it Blechnoxylon. ft Now, 
although :f3X.rj)(i'ov, is literally a “kind of fern,” still, according to 
Loudon it is also “one of the Greek names of the fern,”JJ and may 
* Phil. Trans. (B) for 1895, clxxxvi., p. 754. 
f Ibid., pi. 26, fig. 22. J Ibid., p. 756. 
§ Phil. Trans. (B) for 1895, clxxxvi., p. 766. 
|| Ibid., p. 769. % Ibid., p. 770. 
** Lehrbuch der Pflanzenpalaeontologie, Hief 2, 1897, p. 160. 
ft f3Xrj)(yov and £v\.ov. 
JJ Encyclopaedia of Plants, 1880, p. 881, Note 2183. 
