FILICES. 8 1 



Sori mostly on the back of the veins ; indusium orbicular or reniform, 

 opening all round the margin . . . XX. DRYOFTERIS, p. no 

 J \ Sori at the end of a free vein ; indusium reniform, opening toward 

 the margin of the frond ; fronds simply pinnate, the pinnae articu- 

 lated to the rachis XXI. NEPHROLEPIS, p. 117 



Indusium roundish or stellate, delicate . . XXIV. WOODSIA, p. 119 

 Indusium cup-shaped, somewhat two-valved, 



XXV. DICKSOXIA, p. 121 



Sori all parallel to the midribs or rachises M 



i Sori all oblique to the midribs O 



Sori partly oblique and partly parallel to the midrib ; frond simple, 



I tapering to a point XVIII. CAMPTOSORUS, p. 108 



j Veins free N 



( Veins reticulate XV. WOODWARDIA, p. 102 



Indusium near the margin ; fertile frond much contracted, 



XIII. LOMARIA, p. 101 



' Indusium remote from the margin ; fronds nearly uniform, 



XIV. BLECHNUM, p. 102 

 Sori on the upper side of a veinlet, rarely on both sides, 



XVI. ASPLENIUM, p. 103 



Sori confluent in pairs, with an apparently double indusium open- 

 ing in the middle XVII. SCOLOPENDRIUM, p. 107 



f Sori spread in a stratum on the under surface of the frond, 



I. ACROSTICHUM, p. 82 



I Sori roundish, or not more than twice as long as broad ... Q 

 [ Sori usually linear, always more than twice as long as broad . R 



{Stipes articulated to the rootstock ; fronds (in our species) entire or 

 simply pinnate II. POLYPODIUM, p. 82 

 Stipes not articulated to the rootstock; fronds (in our species) 

 bi tripinnatifid or ternate XIX. PHEGOPTERIS, p. 108 



i Fronds simple & 



Fronds pinnate to quadripinnate T 



Fronds very narrow, grass-like ; veins indistinct, free, 



S -{ VI. VlTTARIA, p. 89 



Fronds broader ; veins anastomosing .... V. T^ENITIS, p. 88 

 f Sori marginal, more or less confluent in a marginal band, 



IV. NOTHOL-iENA, p. 85 



Sori following the veinlets, simple, forked, pinnate, or variously 



anastomosing III. GYMNOGRAMME, p. 84 



\ Sporangia ovate, with transverse ring at apex V 



' Sporangia globose without a ring .... XXX. OsMUXDA, p. 124 

 r ( Stems scandent, pinnas palmate . . . XXVII. LYGODIUM, p. 122 



' Stems not scandent "W 



w \ Sporangia in close distichous spikes . . XXIX. SCHIZJEA, p. 123 

 < Sporangia in copiously branching panicles, XXVIII. ANEMIA, p. 123 

 6 



