XXXIV aOMPENBIUM. 



GENUS 866. PLATYTAENIA. Like genus 86a, but 

 the fronds pinnate and the spores globoso-tetra- 

 hedral. 



FAMILY VII. PARKERIACEAE. Ring incomplete, vertical. Sori inde- 

 finite, consisting of numerous sporangia scattered irregularly 

 along the few, longitudinal veins, covered by the unaltered, 

 recurved margin of the frond v?hen young. 



GENUS 87. CERATOPTERIS. Characters of the fa- 

 mily. 



FAMILY Vlli. OSMUNDACEAE. Ring incomplete, short and horizontal 

 or consisting of a lateral group of thickened cells only. Indusium 

 wanting. 



GENUS 88. OSMUNDA. Sori globose, placed in op- 

 posite, marginal clusters. Segments articulate to 

 the rachis, the fertile ones more or less con- 

 tracted. 



GENUS 89. LEPTOPTERIS. Sori flat, dorsal. Segments 

 not articulate to the rachis, the fertile ones not 

 contracted. 



Seriesi II. Exannulatae. Sporangia without a ring. 



FAMILY IX. MARATTIACEAE. Fronds mostly large, the stipes flanked 

 by 2 stipulaeform appendages at the base. Indusium wanting 

 or inconspicuous. 



GENUS 90. ANGIOPTERIS. Sporangia in 2 opposite, 

 close rows, not concrete. Fronds large, compound. 



GENUS 91. MARATTIA. Sporangia concrete in 2- 

 valved synangia, the valves opposite, boat-shaped. 

 Fronds large, compound. 



GENUS 92. CHRISTENSENIA. Sporangia concrete in 



