1920] TAYLOR—SUCCESSION OF MOSSES 473 



some Hypnaceae as the third vertical la; 

 example of this was found on a low rock 

 1 an open pasture, and at some distance fror 



An especially 



distance from the stream. The 

 top of the rock sloped a little in the downhill direction and was 

 slightly lower than the ground at the upper edge, but was perhaps 

 2 feet above the ground at the lower side. Numerous bushes 

 overhung the upper border, but the lower part was exposed to 

 full sunlight. On the shaded vertical face was a small quantity of 

 a liverwort and an extensive growth of crustose lichens. The 



errow 



much 



■ 



being overgrown by foliose lichens. Growing among and over 



pocarpa. Overlying the edge of the Grim- 



many 



forming a thick compact mat over a large part of the remainder of 

 the rock, except at the upper side where soil had washed over the 



from 



Here 



thecium acuminatum, growing partly on the soil, was extending out 



form 



Small 



lichens and of Grimmia here and there indicated that these at one 



had been Dioneer plants over the entire surface. When the 



time 



more mesophytic species came m, they had developed more 

 llv on the Dart of the rock which received the most moisture 



from 



xng 



m 



form the moss 



xpected, the change in species occurs more 



more 



perpendicular. In some places the cliffs are quite closely covered 



Junip 



Under 



these and often overhanging the edge of the cliff is an undergrowth 



of 



Junip 



e pines in the dune region, except for the greater meso- 

 which is indicated by the herbaceous flora. On vertical 

 rock faces, well shaded and with water dripping over the surface, 



ism 



luxuriant mass of Anomodon 



common 



