BARNES NOETH AMERICAN MOSSES. 189 



DIDYMODON, p. 104. 



Leaf cells throughout quadratic . . . . D. luridus, 104. 



Leaf cells below rectangular. 

 Inflorescence syaoicous . . . . . . D. rubellus, 104. 



Inflorescence dioicous. 



Lid conic, leaves denticulate . . . D. Baden-Powellii, 113. 

 Lid rostrate. 

 Basal cells thick- walled. 



Lamina and costa long papillose D. infos, 115. 



Lamina and costa minutely papillose . D. Henderson!, 114. 

 Basal cells thin walled. 



Perichaetial leaves gradually narrowed . D. cylindrical, 105. 

 Perichsetial leaves abruptly attenuate . D. Canadensis, 112. 



DITRICHUM, p. I05. 1 



Dioicous. 



Leaves slightly twisted. 

 Stem leaves spreading, perichaetial leaves hardly 



sheathing .... . . . D. tortile, 105. 



Stem leaves imbricate, perichaetial leaves long sheath- 

 ing . . D. yaginans, 106. 



Leaves not twisted. 

 Plants short (1-2 cm.), not radiculose. 



Teeth without a basilar membrane . . D. homomallnm, 107. 

 Teeth with a broad basilar membrane . D. ambignnin, 104. 

 Plants long (to 10 cm.), densely radiculose. . D. flexicaule, 107. * 

 Monoicous. 

 Plants short (5-10 mm.). 



Teeth cylindric, legs unequal, nodose-articulate, 



leaves spreading . . . . . D. pall id uni, 107. 



Teeth cylindric, legs equal, obscurely and dis- 

 tantly articulate, leaves spreading . D. montanum, 103. 

 Teeth flattened, linear, trabeculate, perforate, 



leaves secund . . . .. . .. D. Sell im peri, 108. 



Plants longer (2-3 cm.), glaucous . . . D. glaucescens, 108. 



i Leptotrichum Hampe, L. & J. Man. 105. 



a Leptotrichum brevifolium Kindb., Mac. Cat. 46, is described as a subspecies of L, 

 flexicaule Hampe. The characters given however are not sufficient to justify a place in 

 this key. See Appendix, no. 105. 

 3 



