M 



N 



O 



Q 



R 



FILICES. 8 1 



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

 opening all round the margin . . . XX. Drvoi'ieris, p. no 

 Sori at the end of a free vein ; indusium renifornij opening toward 

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

 lated to the rachis XXI. Nephrolepis, p. 117 



( Indusium roundish or stellate, delicate . . XXIV. Woodsia, p. iig 

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



' XXV. DiCKSONIA, p. 121 



Sori all parallel to the midribs or rachises 31 



Sori all oblique to the midribs O 



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



tapering to a point XVIII. Camptosorus, p. 108 



( Veins free N 



( Veins reticulate XV. Woodwardia, p. 102 



Indusium near the margin ; fertile frond much contracted, 



XIII. LOMARIA, p. lOI 

 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 



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



I. Acrostichum, p. 82 

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

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

 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 



Fronds simple S 



Fronds pinnate to quadripinnate T 



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



VI. Vittaria, p. 8g 

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

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



IV. NOTHOL.-ENA, p. 85 



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



anastomosing III. Gymnogramme, p. 84 



( Sporangia ovate, with transverse ring at ape.x V 



( Sporangia globose without a ring .... XXX. Osmund.\, p. 124 



.T ( Stems scandent, pinnae palmate . . . XXVII. Lygodium, p. 122 



' Stems not scandent W 



W 



j Sporangia in close distichous spikes . . XXIX. Schiz.ea, p. 123 

 ( Sporangia in copiously branching panicles, XXVIII. Anemia, p. 123 

 6 



