The Horn-tooth Mosses 



The mature spore-cases are long-egg-shaped, erect or slightly 

 arched, with a short neck. They are dark or pale-red with wine- 

 red or yellow pedicels, and short-beaked, conical lids, becoming 

 deeply furrowed, inclined, and contracted below the mouth 

 when old. 



Leaf. 



Tip of 

 spore-case. 



Peli-cu. 



Portion of 

 peristome. 



C. purpureum. 



There is but one row of teeth, each tooth being cleft into two 

 equal and strongly jointed segments, which suggest the generic 

 name Ceratodon, a compound of two Greek words, tcepas, Ke'paros, 

 a horn, and 6S<av, a tooth. The two characteristics by which one 

 may feel sure that his 

 moss is a horn-tooth, 

 are the cleft teeth and 

 the shape and groov- 

 ing of the spore-cases. 



There are eighteen 

 species in all, one 

 common in North 

 America. 



The Purple 

 Horn-tooth Moss, 

 Ceratodon purpureum, 

 Brid. See Colour 

 Plate IV ^~ P ur P ureum - 



Habit and habitat. Look for the Purple Horn-tooth Moss on 

 rocky ledges in open sunny places of the woods, in pastures and 

 along roadsides, and in vacant city lots. Bright-green cushions 

 of this moss may be found in depressions of the rocks during 



167 



