MOSSES WITH A HAND-LENS 



PAGE 



Growing on rotten wood or occasionally on 



peaty banks 13- 



Growing on soil !4- 



Growing on rocks or cliffs Dicranum. 45 



13. Peristome of four teeth Georgia. 17 



Peristome of sixteen teeth .... Dicranum ftagellare. 49 



14. Plants with hairy calyptra and appearance of 



the Hair-caps Pogonatum. 23 



Plants without hairy calyptra IS- 



15. Peristome of 32 teeth attached to the columella 



as in the Hair-caps Catharinea. 25 



Peristome of 32 hairlike, strongly twisted 



teeth ; leaves crisped when dry 16. 



Peristome of 16 teeth often divided and slender 



at apex but not hairlike or twisted 18. 



1 6. Costa excnrrent into a long white hair. . . .Tortula. 72 

 Costa not excurrent or barely so I/. 



17. Basal hyaline cells forming a V at the base of 



the leaves Tortella. 70 



Line of separation between hyaline and dense 

 cells running nearly straight across the leaf 

 Barbula. 67 



18. Leaves tongue-shaped with long-excurrent costa 



as in Tortula Desmatodon plinthobius. 74 



Leaves short, closely imbricated ; not tongue- 

 shaped Ditrichum. 37 



Leaves long and slender, lanceolate ; costa not 

 excurrent or only shortly so 19. 



19. Plants comparatively large; cells at basal angles 



of leaf abruptly enlarged and usually colored 



Dicranum. 45 



Plants small ; cells at basal angles of leaf not 

 conspicuously enlarged or colored 20. 



20. Plants rusty red ; capsules more than twice as 



Jong as broad Didymodon rubellus. 38 



green; capsule nut moie 111 

 long as broad wl 



21. Plants of sandy fields; leaves crisped when dry 



Weisia viridula. 67 



