IX. MTJSCI. 



927 



anastomosing filaments, unites the outer wall of the sac to the inner wall of the 

 capsule ; the columella is fitted with lax cellular tissue, which rises into "the oper- 

 eulum, and is continuous below with the tissue of the seta. The columella is wanting 

 in some Phascums. 



The SPORES are developed in fours in mother^cetts, which constitute a very soft 

 tissue between the columella and inner walls of the sporangium, and which tissue is 

 rapidly absorbed. Arohidium alone presents an exception to this rule, each mother- 

 cell containing only a single spore. The protkadlus resulting from the germination 

 of the spores is a, cellular confervoid filament, which branches, dichotomously or in 

 tufts, on several points of which buds appear ; these buds become leafy stems, of 

 which some bear archegonia or antheridia, or both. The prothallus is persistent 

 in some minute Mosses with very slender stems (ScMstostega t Ephemerum^ &c.). 



TRIBE I. BRYAOEM. 



Mosses properly so called, stegocarpous or cleistocarpous [capsule dehiscing or 

 not] , Capsule sessile or pedicelled, indehiscent or with a separable operculum ; 

 with or without an annulus, naked, or with a simple or double peristome. 



PRINCIPAL GENERA. 



