146 46. EKICACE^. 



690. Erica Tetralix, Linn. 



Area general. 



South limit in Cornwall, Isle of Wight, Kent. 



North limit in Shetland, Orkney, Hebrides. 



Estimate of provinces 18. Estimate of counties 82. 



Latitude 50 — 61, British type of distribution. 



A. A. regions. Inferagi-arian — Inferarctic zones. 



Descends to the coast level, in the Peninsula. 



Ascends to 750 or 800 yards, in East Highlands. 



Range of mean annual temperatm'e 52 — 39. 



Native. Ericetal. The average limit of this shiTib, in 

 the West of Aberdeenshire, may be taken at 700 yards, in 

 favourable situations. From this point it decreases in a 

 westerly, as well as in a northerly direction ; sinking to 600 

 yards in the West of Inverness-shire, and to 500 yards in 

 the North-west of Sutherland. For some remarks on the 

 curious variety ' E. Tetralix b. Watsoni,' of the London 

 Catalogue, see Erica ciliaris. 



690, b. Erica Mackaii, Z/boA-. 



Hibernian. As several botanists still hold this to be a 

 species distinct from Erica Tetralix, it appears better to 

 keep the notice of the two apart. Plausible, and even rea- 

 sonable, arguments may be advanced in support of either 

 view. Not having visited the habitat myself, I can speak 

 only from dried specimens ; and some of those sent to me, 

 as E. Mackaii (coiTectly, I believe), are so little distin- 

 guishable from the English E. Tetralix, that I should not 

 have thought them worth separating therefrom as named 



