Plants growing on their superincumbent Sozls. 413 
mometer is languid, and the mercury in the weather-glass is 
stationary. Some choose the south, some the north, and others 
the west side of a hedge; one chooses the angle of a rock 
which looks up towards the sky, another lurks beneath the 
hedge, nor will exchange its own dull nook for the sunny glo- 
ries "ae its neighbour. All, in short, of this vast tribe of living 
things, the only living things that are unable to choose their 
place and change it spontaneously, press on our attention the 
singular peculiarity of their geological positions. 
Were we to appeal to experience for another confirmation 
of our theory, we should with confidence refer to the fact, that 
primitive ranges produce the greatest variety and richest spe- 
cimens of vegetables ; a phenomenon derived from the obvious 
aptitude of such rocks to furnish the best and quickest soil for 
vegetable growth. And we should contrast with these ranges 
the poverty and slow production of secondary and diluvial dis- 
tricts: we should simply contrast the shores of Orme’s Head 
and Devonshire with those of Lancashire, and leave each en- 
quirer to his own conclusions, satisfied that they would be 
favourable to the relation we endeavour to establish. 
I proceed next to state several coincidences of similar strata 
with similar vegetables, which have appeared to me not acci- 
dental, but indicative of a constant relation, which time and 
opportunity will corroborate. 
The author, with perfect candour, affords us an instance in 
his paper: — ** It is remarkable,” says he, ‘ that the hill of 
Strathdon (which differs in materials from the neighbouring 
hills) has a peculiarity in its vegetation. The contiguous hills 
are invariably cover ed with heaths ; ; but the hill just mentioned 
derives its name from a green covering of grass : it produces, as 
it is also worthy of notice, Arenaria vérna, Cochlearia officinalis 
and Statice Arméria; of which the two last are rare in that 
quarter ; and as to Arendaria vérna, I never met with it in that 
part of Scotland, unless in the spot mentioned, and again at 
Leslie, growing on the very serpentine rock with which it is 
associated at Strathdon.” 
An instance is afforded in the promontory of Orme’s Head. 
Here the same range of mountain limestone stretches towards 
Anglesea, and has for its link the rock of Priestholm or Puffin 
Island. Not more strikingly do these round hills contrast with 
the bold crags of Penmonmaur and the Caernarvon mountains, 
than do the ‘vegetable coverings of these two contiguous dis- 
tricts. Pyestholva! I understand from my correspondent, Mr. 
Wilson of Warrington, possesses all the peculiar rock plants of 
Orme’s Head except one, Méspilus Cotoneaster, which has been 
found in no other locality in the British Isles. But samphire, 
EE 3 
