Mosses and Lichens 



Genus HYPNUM, Dill. 



The species of the Genus Hypnum in its wider sense all 

 agree in having the peristome double and perfect, the outer of 

 sixteen, strong, lance-shaped, taper-pointed and densely cross- 

 barred teeth; the inner a broad membrane 

 divided to the middle, or about, into 

 sixteen, keeled, yellow segments, dis- 

 tantly cross-barred, entire, or cleft more 

 or less along the keel, the segments 

 generally separated by i to 3 filiform 

 divisions (cilia) cross-barred and often 

 bearing tiny spurs on the margin. 



The difference in the species will 

 perhaps better be understood by refer- 

 ence to the following synopsis of the 

 sub-genera represented by the species 

 which follow. 



Dr. Johnston in speaking of the 

 genus Hypnum said that perhaps it 

 formed one-fourth of the vegetable cloth- 

 ing of Great Britain. 



The word bypnum is the Greek 

 VTTVOV, an ancient name for some sort of 

 moss supposed to promote sleep. 



Hyfmum triquetrunt. Por- 

 tion of peristome showing one 

 outer tooth on the left with 

 annulus cells at its base, two 

 keeled inner teeth on the 

 right with three spurred cilia 

 between. 



SYNOPSIS OF SUB-GENERA 



Thuidtum. Primary stems prostrate 

 and irregularly divided; leaves with tiny 

 protuberances (papillose} ; paraphyllia 

 more or less numerous. 



Stem-leaf. 



Branch. 



Thuidium delicatuhim. 



274 



Cross-section 

 of leaf to show 



papillae. 



Spore -case 

 with lid. 



