THE LICHEN FAMILY. 105 



several instances. Wasps are found with horn-like bodies 

 growing out of their heads, being a species of Sphoeria. 



Sphceria Rohertsii^ a native of New Zealand, is found grow- 

 ing on the head of a caterpillar, which, on burying itself in 

 the earth to undergo its metamorphosis, is attacked by the 

 fungus, which rises like a spike to about six inches in height, 

 and of course kills the caterpillar. A species similar in its 

 habits is found in Tasmania, and S. sinensis^ a native of 

 China, grows in a similar manner. Silkworms are liable to 

 be infested by a minute fungus, Botrytis hasseana, supposed 

 to be a changed state of an alga. Achy la prolifera, which de- 

 stroys gold-fish, giving them quite a woolly appearance. 



The Lichen Family. 



(Lichens.) 



Cellular plants, generally of a grey colour, growing on the 

 earth' rocks, stones, or trees, rarely in water, varying in size 

 and form from a grain like a pin's head to a slender filiform, 

 or broad leafy expansion, either entire or branched. Their 

 reproductive organs consist of circular shield-like bodies, 

 called scutellce, or cup-like cavities, either free, sessile, or 

 borne on a stalk. They occupy extensive plains in high 

 northern latitudes, as also rocky cliffs in the tropical zone. 

 There are upwards of 2500 enumerated species, some few of 

 which produce gelatine used as food, and colouring matter 

 employed in dyeing. 



Iceland Moss {Cetraria islandica). A foliaceous lichen, 

 growing about six inches high, common in this country and 

 throughout northern Europe. It is extensively collected, and ^ 

 made into a nutritious jelly for invalids. ! 



Tripe de Roche, or Eock Tripe. 



A name applied to one or more species of Umhilicaria and 

 Gyrophora. They are circular in form, attached by the 

 centre, and lie nearly flat on rocks to which they cling., 



