108 



Illinois State Academy of Science Transactions 



seems more likely that the reverse is the case since the asymmetry of the 

 steles is probably a specialized feature and this is more extreme in the 

 Nashville stem than in the English Medulloseae. The distelar condition 

 may have come about by elimination of one of the steles of a tristelar form 

 as easily as by the division of the stele of an essentially monostelar plant. 

 The lesser number of steles in the Nashville Medullosa is a feature which 

 serves to distinguish it specifically but this character is less important 

 in itself for judging phylogenetic position. Reduction in complexity of 

 general stelar organization seems more in keeping with features of the 

 histologic organization which will be discussed elsewhere 4 in connection 

 with a diagnosis of the new plant. 



^^p******^, 



ftlfaM&w.ifiiifi 



10cm 



Sutchffia msignis Scott 



Medullosa n.sp. 



,8cm 



, 2cm 



M. pus il la Scott 



Medullosa anglica Scott 



7cm 



5cm 



M. centrof ilis De Fraine 



CROSS- SECTIONS OF STEMS OF CERTAIN MEDULLOSACEAE 



These plants, whose stem structure is so different from those typical 

 of the present are also known to have had fern-like foliage and large nut- 

 like seeds. The male fructification in some instances at least was remark- 

 ably large with tubular sporangia containing male spores which are also 

 much larger and very different from the pollen of modern plants. Even 

 in the case of the best preservations these various organs are habitually 

 found separate from one another. This renders it scientifically impossible 

 to make certain of the specific correlation of seed structure, characters of 

 the male fructification or of the stem or leaf in any single instance which 

 would be comparable with that known for plants living today. We cannot 

 know for certain whether allied stems of different ages with specifically 

 different structure also had different seeds or whether the seed characters 

 were about the same in both cases. The sex organs are considered to be 



