150 



glomerates in the masses of the Longmynd, we encounter in such situations the 

 dry-loving species (or those of the Germanic type) among the more charac- 

 teristic montane species. On the other hand, where the argillaceous schists 

 predominate, or tho quartzose particles of the Lower Silurian rise beneath the 

 argillaceous covering, the soil, cold and humid generally, in dry weather forms 

 an arid, parched crust, covered with heath and moorland, which thus restricts 

 the area for the growth of some montane species, while the bleak, urgenial 

 winds exert a dwarfing effect on others, as in the instance of the diminutive 

 Tormciitilla officinalis and the Heloscidium nodifiorum, which passes into the 

 form of Hdosciadium reptans in such situations. 



As we approach the south- western plateaux, and the more or less fissured 

 and cleaved Pentamerus beds near "Wentnor, we find the difference in the cha- 

 racter of these rocks shown in the Calluna giving way to certain characteristic 

 limestone species, and the escarpments, as we proceed in the same direction, 

 supporting Ranunculus acris, Arenaria trinervis, Erythrcea centaurea, Linum 

 calharttcum, and other calcareous species, while the steep and more grassy slopes, 

 southerly, are crowned more or less with dense woodland. 



From the measurement made by the Trigonometrical Survey, it appears 

 that the highest point in the Longmynd range is 1,674 feet above the sea 

 level. Such an elevation is accompanied by a corresponding Flora, illustrative 

 of the rule " that a small vertical line corresponds to a large horizontal distance 

 from a main point of solar action." 



"We have thus the " superior and mid-agrarian zones " of Watson, in a 

 measure, sketched out. The Pteris aquilina forms, too, a pretty constant 

 limit at 1,200 feet of the Agrarian region. 



Occuping different ranges, the following plants are more or less con- 

 stant : — Erica cinerea, Viola lutea, Veronica hybrida, Galium saxatile, Vaccinium 

 myrtillus, and V. vitis idceus, Vaccinium, oxycoccos, Empetrum nigrum, JVardus 

 stricta, Molinia ccerulca, Myosotis collina, Ccntunculus minimus, Euphrasia 

 officinalis, Fcdia carinata, Sedum anglicum, Jasione montana, Tcucrium scoro- 

 donia, Spergularia rubra, Tormcntilla officinalis, Dianthus deltoides, Hypericum 

 pulchrum, Aspcrula cynanchica, Carlina vulgaris, Cnicus acaulis, Cotyledon 

 umbilicus. Of these, as locally ascending, I would specify Aspcrula cynan- 

 chica in particular, and the rare Dianthus deltoides, which I have met with in 

 one station only, near the Cwms, Spring-bank. 



The Cotyledon umbilicus seems equally partial to the faces of the dark 

 olive schistose rocks at All Strefcton and the porphyritic ledges of Caer Caradoc. 



Spergularia rubra is equally locally ascending. The next division, 

 limited to the higher moorland and slopes, comprises Ulex Europceus, Draba 

 verna, Viola lutea, Veronica hybrida, Drosera rotundifolia, Arctostaphylos uvce 

 urti (Stiper stones), Erica cinerea, Empetrum nigrum, Vaccinium oxycoccos, and 

 V. myrtillus, Lycopodium clavatum, and L. Selago, and Blechnum boreale. 



