304 MOSSES AND FERNS chap. 



rangiate type. The archegonium neck projects much more than 

 in the other Eusporangiatae, and the vascular bundles in the 

 petiole are truly concentric. The venation of the leaves also 

 becomes that of the typical Ferns. The sporangia are com- 

 pletely free and smaller and more delicate, although truly 

 eusporangiate in development. In all these respects there is an 

 approach to Osniunda, unquestionably the lowest of the 

 leptosporangiate series. Hchninthostachys too may be almost 

 as well compared to Osinunda as to Angioptcris. 



On the other hand, in the circinate vernation of the leaf as 

 well as the histology, in the roots and in the sporangia, the 

 Marattiaceae, especially Angioptcris, approach quite as close or 

 closer to the Osmundaceae than does Botrychium or Hehnintho- 

 sfacliys. 



We may conclude, then, from the data at our disposal, that 

 the living eusporangiate Filicineae consist of a few remnants of 

 wide]}- divergent branches of a common stock, which formerly 

 was predominant, but has been supplanted by more specialised 

 modern types. From this primitive stock have arisen on the 

 one hand the leptosporangiate Ferns, and Cycads, on the other, 

 through Isoctcs, or some similar heterosporous forms, the 

 Angiosperms. 



