6. CISTACE^. 171 



Native. Rupestral and Pascual. Distributed widely, yet 

 very unequally. Appai-ently much influenced in its locali- 

 ties by the presence of chalk or harder limestones, and yet 

 found on gravel in some spots where there can be little 

 or no lime within reach of the plants. It occurs also in great 

 local abundance upon various volcanic rocks. Though I 

 have no reference among my notes, to any localities in the 

 provinces of Mersey or West Highlands, the species seems 

 so likely to occur in one or both of those proiances, that I 

 have put down the estimate at 16, and might have said 17 

 even, instead of the ascertained number of 15. By general 

 acquiescence, the H. tomentosum, of English Botany, and 

 the H. suiTeianum are now referred to H. vulgare. 



129. Helianthemum canum, Dun. 



Area * ^ * * [5] 6 7 * * 10 * 12. 



South limit in Glamorganshire, i^i^^-u^*^/' 



North limit in Westmoreland and Yorksliire. 



Estunate of provinces 4. Estimate of counties 8. 



Latitude 51 — 55. Local type of distribution. 



Agrarian region. Inferagrarian — Superagrarian zones. 



Descends nearly to the coast level, in South Wales. 



Ascends to 650 yards, in Yorkshu-e. 



Range of mean annual temperature 50 — 42. 



Native. Rupestral. On the limestone hills of Wales 

 and the north of England; being an example of the Anglo- 

 Cambrian gi'oup of species, mentioned under Draba muralis. 

 Occurs in the counties of Glamorgan, Caemai'von, Angle- 

 sea, Denbigh, Flint, York, Westmoreland (and the north- 

 ern extremity of Lancashire, taken with Westmoreland into 

 the Lake province) and, perhaps, Cumberland. " Penpool 

 Rocks," near Bristol, is a locality published by Mr. Thomas 



