LICHENS AND THE ROCK FLORA. 



241 



of the lichen are united by innumerable connections, 

 which involve an anatomical union. The colour of 

 the upper surface is generally leaden-ash colour to 

 brown, and is fairly conspicuous. Towards the edge 

 of the lichen the lobes spread outwards and often turn 

 slightly upwards. It is at the edge on these lobes that 

 the lichen-cups are found. They are of a conspicuous 



CL 



Fig. 30. — A Lichen (Peltigera canina). (i) View from above with under- 

 surface bent upwards to show the rhizines and nerves : three of the shield- 

 shaped cups are shown at a. (2) Section of lobe greatly enlarged, showing the 

 loose fungus tubes of the central portion which are fused together to form the 

 upper surface ; between them are many small algal cells arranged in a layer 

 ne.ir the top. 



reddish colour, and are about a quarter of an inch \x\ 

 diameter, generally extending almost round the small 

 lobe which carries them. Insects are sure to notice 

 them, and after alighting upon them will probably 

 carry off spores when they leave. 



The " cup," or apotheciinn, of Peltigera is rather 

 different from the type usual in the lichens. In most 

 forms it is like a shallow plate or saucer with or without 

 a rim ; sometimes it is swollen and globular. It is, 

 however, almost always very small, from tV to ^ of 

 an inch in diameter. The bottom of the cup is covered 



(B7) Q 



