CHAPTER XXX. 



II. MEDULLOSEAE. 



The term MeduUoseae was first employed by Goeppert and 

 StenzeP for a family of Palaeozoic plants that appears to have 

 reached its maximum development in the Permian period : the 

 oldest representatives so far discovered are of Upper Carboniferous 

 age. Our knowledge of the family is chiefly derived from a study 

 of the anatomical characters of stems, and it is therefore on this 

 basis that any grouping of genera or species should be attempted. 

 Although there is httle information with regard to the reproductive 

 organs of Medullosa, the type-genus, it is certain that the Medul- 

 loseae are Pteridosperms differing from members of that group 

 included in the Lyginopterideae in the presence of more than one 

 stele in the stem, in the habit of the fronds, and in the structure 

 of the rachis, as also in the structure of the seeds, though these 

 organs bear a fairly close resemblance to the seeds of Lyginopteris 

 and Heterangium. The fronds of the Lyginopterideae are of the 

 Sphenopteris type while in the case of such species of Medullosa 

 as afford evidence of connexion between stems and leaves the 

 latter have the characters of Neuropteris, Aleihopteris, Odonto- 

 pteris, Linopteris, and other form-genera usually included in 

 the Neuropterideae. Dr Lotsy^ speaks of Lyginopteris and 

 Heterangium as members of the SphenopteridophyUa and assigns 

 species of Medullosa either to the NeuropteridophyUa or to the 

 PecopteridophyUa, the latter subdivision including species with 

 fronds of the Alethopteris type. There is, however, little doubt 

 that other forms of leaves, such as Odontopteris and possibly 

 Taeniopteris, were borne on Medullosan stems. It is undesirable 



1 Goeppert and Stenzel (81). 2 Lotsy (09) p. 723- 



