50 Illinois State Labonitori/ of Natural History. 



{ Midrib wantinsr or not apparent C 



i Midrib clearly apparent D 



f Sporogonium dorsal ; elaters bispiral, free. 11. Pellia, 



ri J Sporogonium borne on nnder side of thallus near the 

 I margin; elaters unispiral, adherent to the apex of 



1^ the valves. I. Aneuea. 



D^ 



E 



F^ 



G 



H 



Inner involucre tubular, at first terminal, at length 

 dorsal; thallus sinuate or lobed. IV. Steetzia. 



Inner involucre wanting or early vanishing E 



Outer involucre wanting; fructification apical; thallus 

 simple or bifid. III. Blasia. 



Outer involucre monophyllous, ventricose; sporogonium 

 arising from lower surface of midrib; thallus fur- 

 cate. V. Metzgeria. 



" Leaves incubous : i. e. the apex lying on the base of the 

 next one above G 



Leaves succubous: i. e. the apex lying under the base of 

 the next one above 



Leaves bilobed or with a small ventral lobe at base. .H 



Leaves without ventral lobe at base, mostly 3-5-toothed, 

 lobed or parted L 



Amphigastria present* I 



Amphigastria wanting; lower lobe usually convex un- 

 derneath. XL Radula. 



r Amphigastria entire or 2-tootlied K 



I Amphigastria 4-5-lobed; lobes of leaves divided. XIII. 

 1^ Blepharozia. 



Amnbigastria are obsolete or wanting in tliree species of Lejeunia- 



