CHAPTER XXXI. 



PTERIDOSPERMS REPRESENTED BY SEED-BEARING LEAVES 

 ONLY OR LEAVES IN CONSTANT ASSOCIATION WITH 

 SEEDS. 



Before describing other genera represented by petrified 

 vegetative organs exhibiting in their anatomical features points 

 of contact with the MeduUoseae, a short account is intercalated 

 of some imperfectly known seed-bearing fronds and seeds belonging 

 to the Pteridosperms but which do not afford sufficient data to 

 admit of their reference to a more precise position in a natural 

 classification. 



Pecopteris PlucJceneti (Schlotheim). 



In the section in Volume ii. devoted to the genus Pecopteris 

 reference was made to the species P. Pluckeneti^, further treatment 

 being deferred until other Pteridosperms had been described. 

 The fern-like fronds originally described by Schlotheim as Filidtes 

 Pluckeneti^ and afterwards transferred by Brongniart and other 

 authors to Pecopteris^ are now recognised as the leaves of a 

 Pteridosperm. Some doubt has been expressed as to the specific 

 identity of the specimens figured by Schlotheim and Brongniart 

 respectively, but Potonie's examination of the type-specimen 

 of the earlier author convinced him that Brongniart's leaves were 

 correctly named. The large fronds of Pecopteris PlucJceneti are 

 characterised by the bifurcation of the principal axis which bears 

 opposite pairs of bi- or tri-pinnate branches and in the angles of 

 the bifurcations of the rachis undeveloped buds occur on prolonga- 

 tions of the axis, a habit recalling recent species of Gleichenia^ 



1 Vol. n. p. 576. ^ Schlotheim (04) A. PI. x, fig. 19. 



^ For synonomy, see Kidston (86) A. p. 125 and Potoni6 (93) A. p. 81. 

 » Sterzel (83); (86^) B.; Zeiller (06) B. p. 60. 



