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TRIBE I. CYATHEA 



Tree-ferns. Sori dorsal, round ; sporan- 

 gia stalked or sessile on an elevated 

 receptacle ; indusium inferior, in the form 

 of a scale beneath the sorus, or completely 

 enveloping the sorus, ultimately bursting 

 at the top and forming a cup. It is absent 

 in Alsophila. 



Caudex arborescent ; indusium globose, 

 ultimately rupturing at the apex so as to 

 form a cup holding the sorus. 



Genus II. Cyathea 29 



Caudex arborescent ; sori round, naked. 



(Distinguished from Cyathea by the 

 absence of indusium). 



Genus III. Alsophiia R. Br. 31 



TRIBE II. DICKSONIE.E 



Sori round, at the back or apex of a 

 vein ; indusium inferior, leathery, mounted 

 on a stalk, covering the whole sorus and 

 bursting irregularly, or cup-shaped, entire 

 or two-lipped. Veins free or anastomosing. 



Sori round, arising from the back of a 

 vein or veinlet ; indusium inferior, globose, 



