196 BULLETIN OF THE UNIVEESITT OF WISCONSIN. 



II. Leaves not bordered. 



Cells smootti B, mncronifolia, 131. 



Cells papillose. 

 MonoicouB. 



Costa percurrent .... j„ ,. , ^* *''®'"i?*®' Jli" 



^ ( B. snbnlata mntica, 130. 



Costa excurrent into a long (mostly smooth) hyaline 



hair; on trees B. laeripila, 132. 



Costa excurrent into a short point; on rocks . B. alpina, ISX, 



Polygamous, costa excurrent into a hyaline spinulose 



hair B. Muelleri, 133. 



Dioicous. 



'Costa percurrent or ceasing below apex . . B. latlfolia, 132, 

 Costa short-excurrent, clothed above with gemmae B. papillosa, 133. 

 Costa naked, excurrent into a hyaline, spinulose hair. 

 Hair white throughout. 

 Tube of peristome nearly equaling purple teeth in length. 

 Peristome twice twisted. 

 Costa abruptly excurrent. 

 Hair point spinulose . . . B. ruralis,' 132. 



Hair point nearly smooth . . . B. leptotricha, 1S9. 

 Costa gradually excurrent . . . B. raraliformls, 15S. 

 Peristome once twisted . . . . B. iBtermedia, 167. 

 Tube of peristome much shorter than the pale 



teeth B. laeTinscnla, 165. 



Hair red at the base or throughout. 

 Leaves not sheathing, patent when 



moist B. rotnndo-emarginata, 161. 



Leaves sheathing, squarrose-spreading, all the 



margin recurved B. aciphylla, 168. 



Iieaves sheathing, curved, margin slightly re- 

 curved in the middle . . . B. bfachyangia, I64. 



The very great similarity of BB. ruraliformis, hranchyangia, Icsvi- 

 usoula, papillinervis, intermedia, aciphylla, leptotricha and lato-ex- 

 cisa renders it more than probable that they are all forms of the extremely 

 variable and polymorphic B. ruralis, as B. megalocarpa Kindb. is; 

 wherefore the key is likely to prove useless in distinguishing them. 



I See Appendix, no. 152. 



