196 BULLETIN OF THE UNIVERSITY OP WISCONSIN. 



II. Leaves not bordered. 



Cells smooth B. nmcroni folia, 131. 



Cells papillose. 

 Monoicous. 



Costa percurrent . | B. snbuUta 'Set' m 



Costa excurrent into a long (mostly smooth) hyaline 



hair; on trees B. laevipila, 132. 



Costa excurrent into a short point; on rocks . B. alpiua, 151. 

 Polygamous, costa excurrent into a hyaline spinulose 



hair B. Muelleri, 133. 



Dioicous. 



Costa percurrent or ceasing below apex . . B. 1 at i folia, 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, 1 132. 



Hair point nearly smooth . . . B. leptotricha, 159. 



Costa gradually excurrent . . . B. ruraliformis, 153. 



Peristome once twisted . . . . B. intermedia, 157. 



Tube of peristome much shorter than the pale 



teeth B. heviuscula, 155. 



Hah* red at the base or throughout. 

 Leaves not sheathing, patent when 



moist B. rot n n do-em arginata, 161. 



Leaves sheathing, squarrose-spreading, all the 



margin recurved . . . . . B. aciphylla, 158. 

 Leaves sheathing, curved, margin slightly re- 

 curved in the middle B. brachyangia, 154. 



The very great similarity of BB. ruraliformis, branchy 'angia, Icevi- 

 uscula, 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. 



1 See Appendix, no. 152. 



