Plants growing on their superincurnberit Soils. 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 of 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 covered 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 verna, Cochlearia officinalis 

 and jStatice Armeria ; of which the two last are rare in that 

 •quarter ; and as to Arenaria verna, 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. Priestholm, I understand from my correspondent, Mr. 

 Wilson of Warrington, possesses all the peculiar rock plants of 

 Orme's Head except one, ikfespilus Cotoneaster, which has been 

 found in no other locality in the British Isles. But samphire, 



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