MUSCINEJ3. 195 



moors, which they cover with a thick carpet saturated with water. 

 The lower extremities of the plants perish very rapidly, and 

 gradually become converted into peat, and the branches thus 

 separated from each other become independent plants. The 

 sporangia (Fig. 199 D, E) are spherical, but with a very short 

 stalk. They open by a lid, but have 110 annulus. The archegonium 

 (Fig. 199 (7) persists at the base of the sporogonium as in the 

 Liverworts. Only one genus, Sphagnum. 



Family 2. Schizocarpeae. 



The Mosses which constitute this family are of a brownish -black colour and 

 are found living on rocks. The sporangium resembles that of the Liverworts 

 inasmuch as it opens by four valves, but these continue attached to each other at 

 the apex as well as at the base (Fig. 193). There is only one genus : Andreaa. 



B. The stalk is formed from the lower portion of the sporogonium. The 

 columella is continued to the summit of the sporangium and united with it 

 (Arclddium has no columella.) 



Family 3. Cleistocarpeae. 



The fruit does not dehisce in the regular way, but the spores are liberated by 

 decay. They are small Mosses which remain in connection with their protonema 

 until the sporangium is mature. The archegonium remains sessile at the base 

 of the short capsule-stalk, and is not raised into the air (compare Hepaticae). 

 Phascum, Ephemerum, Archidium, Pleuridium. 



Family 4. Stegocarpeae. 



To this belong the majority of the Mosses, about 3,000 species. 



The capsule opens as in Sphagnum by means of a lid (operculum) , 

 which is often prolonged into a beak. Round the mouth of the 

 opened capsule, a number of peculiar yellow or red teeth are to be 

 found. These constitute the peristome ; their number is four, or a 

 multiple of four (8, 16, 32 or 64). The form and thickenings 

 of these teeth are widely different, and on this account are used by 

 Systematists for the purposes of classification. In some Mosses 

 (Fig. 200 0, D) there is a double row of teeth. Except in 

 Tetraphis they are not formed from entire cells, but from the 

 strongly thickened portions of the wall of certain layers of cells 

 belonging to the lid, and persist when this falls off. They are 

 strongly hygroscopic, and assist greatly in the ejection of the lid, 

 in which operation they are considerably aided by a ring of elastic 

 cells with thickened walls, situated in the wall of the lid near the 

 base of the teeth. This ring is known as the annulus. The arche- 

 gonium. is raised into the air like a hood, the calyptra, which 



