228 FERNS I BRITISH AND FOREIGN. 



116. HEMIDICTYUM, Presl. 



Vernation fasciculate, erect. Fronds pinnate, 10-14 feet long ; 

 pinnae 1-2 feet long, 3-5 inches wide. Veins forked ; venules 

 parallel till near the margin, then anastomosing and reticulated, 



Genus 116. Portion of fertile pinna, under side. No. 1. 



combined by a transverse, continuous, marginal vein. Sporangia 

 produced on the superior side of the parallel veins, constituting 

 unilateral, linear sori. Indicium plane. 



1. H, marginatum, Presl ; Hook. Gen. Fit. t. 55 A. Asple- 

 nium marginatum, Linn, (Plum. Fil. t. 106) ; Hook, 

 Fil Exot. t. 73 ; Lowe's Ferns, 5, t. 53. Diplazium 

 giganteum, Sort. Linden. Tropical America. 



117. CETERACH, Willd. ; J. 8 



nn. 



Vernation fasciculate, erect, caespitose. Fronds 2-12 inches 

 long, sinuose-pinnatifid or pinnate, the under side densely squa- 

 mose. Veins forked, anastomosing. Sporangia unilateral, 

 protruding through the dense squamae, forming oblong sori. 

 Indusium obsolete. 



