Plants growing on their supérincumbent Soits. 417 
Erédium cicutarium, or moschatum, belongs, I am inclined 
to believe, to the new red sandstone. The sand-hills of Bootle 
and Southport are covered with it, and considerable quantities 
appear on the banks of the Irwell at Barton. 
The slate and transition limestone districts claim Convélvu- 
lus Soldanélla. The only localities I ever found of this plant 
are, the mouths of the river Conway, and of the Ex in De- 
vonshire. 
The heaths are found most luxuriant where granite or other 
primitive rocks are found. * ‘These plants, as their names im- 
ply, are found always on bog soil; and, as the component 
particles of that earth may be taken as similar every where, 
yet it cannot be denied that the heaths of different contiguous 
hills are extremely different both in kind and degree. Red 
heather (Hrica cinérea) is the only species found for miles 
together on the greywacke of the Isle of Man; /. Tétralix, the 
only species for several hundred yards on Blackstone Edge ; 
E. vulgaris is the only species for miles on the granite of 
Goatfell, in the Isle of Arran. Each of these species may be 
found in sufficient quantity wherever bog soil is found ; but 
they may reasonably be claimed by those districts only, where, 
with equal climates, they are produced in greatest luxuriance : 
and few observers of the common features of a landscape can 
have failed to notice the great diversity of character in these 
universal natives of our moors, in the different geological 
arrangements of the country. Few can have omitted to notice 
the total want of them on bog whose substratum is chalk or 
mountain lime; and many have been delighted with their 
abundance and surpassing beauty in the primitive ranges of 
Wales and Scotland. The ling of Pont Aber Glas Llyn, 
near Reddgelert, yields to none in the richness of its flowers ; 
and that of the granite range of Avan, in the Frith of Clyde, 
is often 34 ft. in ‘height, arborescent, and erect, like the finest 
specimens of Cape heaths cultivated in our green-houses. 
The poor natives of that island make an economical substitute 
for hemp from its twigs; and the roots, occasionally thrown 
out of the soil by the fury of a mountain-torrent, are 2 in. in 
thickness, and capable of a high polish, being nearly as hard 
as ebony. The Cape of Good Hope itself, which has supplied 
our exotic collections with nearly 300 species of this genus, is 
one of the finest granite ranges in the world. 
Several species of 7'vifolium are found ina singular manner 
* Were it possible to conceive the universality of a vegetable soil, what 
would be the effect ? I presume, a decrease of vegetation in general, and a 
total extinction of those plants best fitted to support animal life ; the whole 
of which, nearly, are the productions of rock soil. 
