526 MANUAL OF NATURAL HISTORY. 



ceous ; stemless, creeping or floating ; leaves 

 often stalked ; vernation circinnate ; repro- 

 ductive organs enclosed in an involucre, and 

 of two kinds 1, membranous sacs, clustered, 

 stalked, or sessile, containing minute granules ; 

 2, membranous sacs, containing cells, which 

 divide into four, only one of which ger- 

 minates. Inhabit ditches and wet places, 

 chiefly in temperate countries. (Rhizocarpce, 

 Agardh.) 



2. FAMILY. Club-Mosses (Lycopodiacese). Herba- 

 ceous, moss-like ; stems creeping or corous ; 

 leaves imbricated, sometimes subulate ; spore- 

 cases axillary, sessile, 1-8-celled, dehiscing by 

 valves, or indehiscent ; at times of two kinds, 

 the one enclosing minute, powdery matter, 

 the other containing a cell, which produces 

 four germinating bodies. Most abundant in 

 warm, humid situations, especially in tropical 

 islands ; but occur also in cold climates. 



III. ORDER MUSCALS (Muscales). 



Cellular or vascular ; spore-cases either plunged 

 in the substance of the frond, or enclosed in a cap- 

 like hood. 



I. SUB-ORDER.- OPERCULATE-MOSSES (Musci). 



Operculum present ; no elaters. 

 1. FAMILY. Urn-Mosses (Bryacese). Cellular; erect 

 or creeping, terrestrial or aquatic ; leaves mi- 

 nute, imbricated, entire or serrated ; repro- 



