FIL1CES. 8 1 



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

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

 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 

 K -j Indusium cup-shaped, somewhat two-valved, 



XXV. DICKSONIA, p. 121 



Sori all parallel to the midribs or rachises M 



Sori all oblique to the midribs O 



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



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



( Veins free X 



\ Veins reticulate XV. WOODWARDIA, p. 102 



f Indusium near the margin ; fertile frond much contracted, 



XIII. LOMARIA, p. 101 

 i Indusium remote from the margin ; fronds nearly uniform, 



XIV. BLECHNUM, p. 102 



iSori 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 



j 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 S 



' Fronds pinnate to quadripinnate i . . . T 



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

 VI. VITTARIA, p. 89 

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

 (Son marginal, more or less confluent in a marginal band, 

 IV. NOTHOL/EXA, p. 85 

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

 anastomosing III. GYMXOGRAMME, p. 84 



\ Sporangia ovate, with transverse ring at apex V 



I Sporangia globose without a ring .... XXX. OSMUNDA, p. 124 

 y \ Stems scandent, pinnae palmate . . . XXVII. LYGODIUM, p. 122 



' Stems not scandent ~W 



w i Sporangia in close distichous spikes . . XXIX. SCHIZ^EA, p. 123 

 \ Sporangia in copiously branching panicles, XXVIII. AXEIMIA, p. 123 

 6 



