F, Plants reddish; leaves less than 1.5 mm. long; cells greatly bulg- 

 ing on the upper leaf-surface. 4. R. cyclodictyon 

 FF. Plants green to blackish; leaves 2 mm. or more long; cells not 

 or hardly bulging on the leaf-surface. 

 G. Leaf-tip rounded, often toothed, but sometimes entire. 



2. R. aciculare 



GG. Leaf-tip bluntly pointed, entire. 



H. Leaf-margin i cell thick throughout; short tuft-like lateral 

 branches o to few. 3. R. depressum 



HH. Leaf- margin more than i cell thick above; short tuft- 

 like lateral branches many. i. R. affine 

 BB. Hyaline points present on some leaves, at least on some of those of the 

 branch tips. 



L Leaves plainly papillose on both sides; seta twisted to the left. 



10. R. canescens 



II. Leaves not or hardly papillose. 



J. Leaves with 2-4 ridges several cells high on the under side of the vein; 



seta twisted to the left. 8. R. patens 



J J. Leaves without longitudinal ridges on the vein; seta twisted to the right. 

 K. Isodiametric cells restricted to the marginal row above, and to a 

 few cells in the tip; capsule body 3.3-3-8 mm. long. 9. R. varium 

 KK. Isodiametric cells predominating above except in the vein; cap- 

 sule-body 2.4 mm. or less long. 

 L. Leaf- margin only i cell thick throughout. 5. R. heterostichum 

 LL. Leaf-margin more than I cell thick near the tip. 



M. Hyaline leaf-points acute, always present on some leaves of 

 the branch-tips; short tuft-like lateral branches o to few. 



6. R. sudeticum 



MM. Hyaline leaf-points blunt, always present on some leaves 

 of the branch-tips; short tuft-like lateral branches o to few. 



7. R. macounii 



MMM. HyaUne leaf-points none at all or blunt or few; short 

 tuft-like lateral branches many. 8. R. affine 



AA. Upper green leaf-cells 2 01 more times as long as wide. 



N. Leaves with papillose hyaline points, or if all leaves without hyaline points 

 the green cells papillose; seta twisted to the left. 

 O Green cells papillose on both leaf-surfaces; upper green leaf-cells 1-2 

 times as long as wide exclusive of vein. 10. R. canescens 



00. Green cells not papillose except within a few cells of the hyaline point; 

 upper green leaf-cells 2-8 times as long as wide exclusive of vein. 



II. R. lanuginosum 

 NN. Leaves wholly without papillae; seta twisted to the right. 

 P. Vein extending to the leaf-tip or very nearly there. 



Q. Most of the leaves with hyaline points; seta 4-5 mm. long; capsule- 

 body 1. 8-2. 1 mm. long; peristome-teeth about .6 mm. long; leaf- 

 surface depressed over the cell-wall. 12. R. microcarpum 



