The Present Position of Palaeozoic Botany. 207 



the solid centripetal wood consisting of pitted tracheides interspersed 

 with bands of pareuchj^ma. From the principal stele, large vascular 

 strands, the meristeles or subsidiary steles, are detached, which divide 

 up and fuse with one another, ultimately giving rise to the leaf-trace 

 bundles, a large number of which enter the leaf-bases. The petiolar 

 bundles are concentric, resembling those of Seward's Rachiopteris 

 WiUiamsoni, which was no doubt the petiole of another species of 

 Sutdiffia. In the specimen investigated, secondary growth in thickness 

 was only just beginning. In habit and various structural details, the 

 plant agrees with a Medullosa ; it shows a near approach to monostelic 

 structure, for the single central cylinder forms the dominant feature 

 in the vascular system, while the meristeles eflect the transition to 

 the leaf-traces. The concentric foliar bundles constitute a more Fern- 

 like character than is known elsewhere among the Medulloseae. The 

 plant is of considerable interest, as indicating the probable derivation 

 of the MeduUosean stem from a simple protostelic type, such as occurs 

 in Hetermifjium among the Lyginodendreae. 



As regards habit, there can be no doubt that the Medulloseae 

 were plants of very large size. Petioles of Medullosa nearly 15 cm 

 in diameter are known, and those of Sutdiffia approached the same 

 dimensions. The repeatedly pinnate leaves, with the habit of a 

 huge Osmimda (as in Nenropteris) or Amjiopteris (as in Alethopteris) 

 were borne on stems probably resembling those of Tree-ferns; in a 

 Medîdiosa from Saxony the decorticated stem measures 48 >< 45 cm in 

 diameter. The specimens of Medullosa amjlica show that the stem was 

 completely clothed by the decurrent bases of the leaves. 



M. Grand'Eury's extensive observations on the association 

 between fronds and seeds of definite species, not only in Alefliopteris 

 and Neuro2)teris, but in Odontopteris, Linopteris, Loncliopteris, etc. have 

 convinced him that the Neuropterideae generally were seed-bearing 

 plants of Cycadean affinities. There can be no question that all the 

 existing evidence points in this direction, while throughout the whole 

 of the family there is practically an entire absence of any counter- 

 vailing evidence on the Fern side. 



We have as yet scarcely any knowledge of the nature of the 

 male organs in this family. In 1887 Mr. Kids ton described a form 

 of fructification in Neuropteris lieterophijlla. the same species in which 

 he afterwards discovered the seed. The specimen shows a forked 

 rachis, bearing the normal vegetative pinnules below, while the 

 branches terminate in four-lobed bodies, which may be interpreted 

 either as groups of sporangia or as cupules. As there is no reason 

 to suspect the presence of cupules in the Neuropterideae. the former 

 view is perhaps the more probable, in which case the specimen would 

 no doubt represent the microsporangiate fructification; M. Grand' 



