PLATE XXXIX. 



[Proc. Wash. Acad. Sci., Vol. IV, PI. XXII.] 



Figs, i, a-f. Polytrtchum yukonense. 



1, a. Entire plant, natural size. 



I, b, b. Leaves ( X ^S)- 



1, c. Transverse section of a leaf ( X34)- 



I, d. Transverse section of a lamella ( X i35)- 



1, e. Part of a lamella seen from side ( X 270). 

 i,f. Basal areolation of the leaf ( X ^SS)* 



2, a. Polytrichum jensenit. 



2, a. Basal areolation of the leaf ( X i35)« 



3, a-e. Brachythecium beringianum. 

 3, a. Entire plant, natural size. 

 3,3. Stem leaf ( X 26). 



3, c, c. Branch-leaves ( X26). 



3, d. Basal areolation ( X I3S)« 



3, e. Cells in the middle ( X 270). 



4, a-e. Plagiothecium fallax. 



4, a. Entire plant, natural size. 



4, <5. Leaf (X 13)- 



4, c. Perigonial leaf ( X 26). 



4, d. Basal areolation of a leaf ( X ^35) 



4, e. Areolation in the middle ( X I35)' 



5, a-e. Hyfnum treleasei. 



5, a. Entire plant, natural size. 

 5, b, b, b. Leaves ( X26). 



5, d. Basal areolation of a leaf ( X 270). 



5, e. Cells in the middle ( X 270). 

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