THE MOSS FAMILY. 



107 



fraxinea and B. farinacea are most common, and generally 

 their growth denotes unhealthy forest vegetation. They 

 yield but a small amount of colouring matter. 



Manna {Lecanora esculenta). A crustaceous species of a 

 grey or brownish colour, growing on the mountains of 

 Armenia, and other countries of Asia Minor. At some period 

 of its growth it becomes dried up, and is blown by the winds 

 to a considerable distance, eventually falling, and covering 

 the ground with a coat several inches in depth ; the inhabitants 

 suppose that it falls from heaven. In times of scarcity it is 

 ground up with corn, and used for food. This plant is found 

 abundantly in the desert in which the children of Israel so- 

 journed, and is by some travellers and commentators sup- 

 posed to be the substance they called manna. Showers of 

 it have fallen in Algeria. 



Cudbear {Lecanora tartar ed). A common crustaceous 

 lichen, formerly very extensively used in Scotland for dyeing 

 wool. 



Parmelia parietina. One of the most beautiful crustaceous 

 lichens, covering trees, or walls with a fine yellow, or redi 

 tinge. It has been highly valued as a dye. 



CLASS II.— ACROGElSrS. 



Leafy plants, having stems with a firm central axis, 

 which branches into the cellular laminae forming midribs, 

 and veins. Keproduced by spores, contained in special 

 spore cases {sporangia, thecce, dc). 



This class contains mosses, club-mosses, ferns, and 

 horse-tails (fig. \l, a,h, c). 



THE MOSS AND LIVERWOET ALLIANCE. 

 The Moss Family. 



(Bryace^, or Musci.) 



Plants with erect, or creeping, simple, or branched 

 stems, the central axis being composed of firm, elongated 



