xx] 



GLEICHENIACEAE 



289 



semi-circular in form (fig. 226, C), in others (sect. Mertensia') 

 the segments are linear (fig. 226, D), and in many species the 

 fronds are distinguished by the regular dichotomous branching 



Fio. 224. A. Aneimia flexuosa. 



B. A. phyllitidis. 



C. Hymeiwphyllum dilatatum. 



D. E, F, G. Matonia pectinata; i, indusium. 

 H. Thyrsopteris elegans. 



I. Gleichenia circinata. 

 (A, B, after Prantl ; C, G, H, I, after Bower.) 



1 Underwood (07), p. 243, has adopted Bernhardi's genus Dicranopteria in 

 place of Mertensia on the ground that the latter was used as early as 1793 for a 

 Boraginaceous plant. 



