AFFINITIES OF MEDULLOSEAE 463 



various Neuropterideae possessed stolons and other 

 means of vegetative propagation. 1 



Affinities of Medulloseae 



We may provisionally treat the family names Medul- 

 loseae and Neuropterideae as synonymous, for though 

 there can as yet be no strict proof that the groups 

 indicated were coextensive, yet there is evidence that 

 the Medullosean type of structure existed in several 

 of the genera with Neuropteridean characters in the 

 frond. 



In the Medulloseae, as in the Lyginodendreae, we 

 are able to point to definite structural characters, quite 

 apart from the habit, which indicate affinity with the 

 Ferns. So far as Medullosa itself is concerned, the 

 most Fern-like feature is the vascular system of the 

 stem, which in its primary " polystelic " arrangement 

 appears essentially Filicinean, and was compared by 

 Weber and Sterzel in 1896 with that of Psaronius. 

 The fact that this original ground-plan becomes more or 

 less obscured as secondary growth goes on does not 

 affect the significance of the primary structure, but a 

 more serious difference from the Ferns consists in the 

 absence of leaf-gaps in Medullosa (see above, p. 444). 

 The discovery of the Sutcliffia type of vascular system, 

 which may be described as a modified protostele, renders 

 it probable that polystely arose within the family 

 Medulloseae, and if so we must regard this character 

 rather as a parallel development to the polystely of 

 the Ferns than as a direct inheritance from them. In 



1 C. Grand'Eury, " Sur les organes et le mode de vegetation des Neuro- 

 pteridees, et autres Pteridospermes," Comptes Rendus, t. 146, p. 1241, 1908. 



