BARNES NOBTH AMERICAN MOSSES. 171 



II. Cortical cells of stem and pendent branches al- 

 ways with fibrils and pores; branch leaves not 

 blunt and toothed but cucullate and hyaline 

 bordered . . . . . VII. Cjmbi folia, p. 175. 



I. Acutifolia. 



A. Branch leaves toothed only at blunt apex, without resorption 

 furrows on margined border. 



i. Stem leaves lacerate-f ringed at apex. 



a. Stem leaves with completely resorbed cell membranes in upper 



part, without fibrils. 



Stem leaves widening upward, spatulate, apex and 



upper margins lacerate-fringed . . . S. fimbriatnm, 14. 



Stem leaves not widening upward, linguiform and lacer- 

 ate fringed only at broad round apex . S. Girgensohnii, 1 13. 



b. Stem leaves with resorbed membranes only at apex, 



upper % to % with fibrils . . . . S. Bolanderi, 1. 



2. Stem leaves usually dentate at apex, nowhere with completely 

 resorbed cell membranes. 



a. Stem leaves slightly or not at all narrowed upward, linguiform. 



Outer wall of cortical cells always porose . . S. Rnssowii, 2 . 

 Outer wall of cortical cells without pores. 

 Branch leaves curved when dry, erect-spreading, stem 



leaves without fibrils. 



Pores of branch leaves very small, near apex, S. Warnstorfli, S. 



Pores of branch leaves of medium size or large S. Yancouveriense, 4. 

 Branch leaves frequently secund, stem leaves frequently 



with fibrils, wood-cylinder never brown . . S. tenellum, 5. 

 Branch leaves densely imbricate, stem leaves without 



fibrils, wood-cylinder always brown . . .- S. fuscum, 6. 



b. Stem leaves distinctly narrowed above. 



Branch leaves when dry plainly 5 ranked . . S. quinquefarium. 7. 

 1 8. strictum Lindb. 



