196 BULLETIN OF THE UNIVERSITY OF WISCONSIN. 



II. Leaves not bordered. 



Cells smooth B. macronifolia, 131. 



Cells papillose. 

 Monoicous. 



Costa percurrent .... S « . k i ^Z '"®T'^' iqI' 



^ ( B. sabnlata matica, 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, 151. 



Polygamous, costa excurrent into a hyaline spinulose 



hair B. Muelleri, 133. 



Dioicous. 



Costa percurrent or ceasing below apex . . B. latifolia, 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, 159. 

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

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

 Tube of peristome much shorter than the pale 



teeth B. lasTiuscula, 155. 



Hair red at the base or throughout. 

 Leaves not sheathing, patent when 



moist B. rotundo-emarginata, 161. 



Leaves sheathing, squarrose-spreading, all the 



margin recurved B. aciphylla, 158. 



Leaves sheathing, curved, margin slightly re- 

 curved in the middle . . . B. brachjangia, 154. 



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

 usGula, 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. megalocarjja Kindb. is; 

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



1 See Appendix, no. 152. 



