Watson's climatic zones. " 83 



their own in North Cardiganshire at 1500 ft. On this they remark: 

 " We find that the Plinhmmon region is in this respect similar to 

 the High Peak region, but dissimilar to the Lake region and the 

 East Highlands": but, if this were the case, the Pteris ought to 

 mount higher in North Cardiganshire with its higher hills than in 

 the Peak District. The reason it does not do so is that the hills 

 do not rise from a table-land in the former as they do in the latter. 

 The expectation that as Pteris grows to 1900 ft. in the East High- 

 lands, they should "get it possibly at 2300 ft., or at any rate 

 2000 ft. in Mid Wales," is founded, I think, on the same mis- 

 apprehension. Again, it is stated : " Using Baker's test of the 

 fruticose Eubi (exclusive of M. flssiis) to determine the top limit of 

 the mid-agrarian zone, we find it to end about 750-850 ft. This 

 is again lower than Watson's limit in the East Highlands.'' 

 Watson gives the limit of R. fruticosus L. there at 250 or 300 yds. 

 But in Journ. But. 1891, p. 48, there is an article by Mr. Baker on 

 Eubi in Wales where one species is mentioned as occurring at 

 1000 ft. on the Llanberis side of Snowdon, and this does not 

 appear to be even on the south side of the hill. This latter altitude, 

 being taken from a higher hill, gives a fairer estimate of the 

 climatic zone in Wales as compared with the East Highlands, and 

 would seem in itself evidence that the hills given in North 

 Cardiganshire are too low for this purpose, there not being three- 

 quarters of a degree of difference of latitude between the two Welsh 

 localities. If the authors' conclusions were followed out, it would 

 entail different zones for every small hill or small group of hills, 

 with the arctic zone to descend in proportion to the lowness of 

 altitude of the hills, provided they have a few rocks and some 

 exposure. 



It may be here remarked that altitudes of plants on the 

 Snowdon range are much required. On the warm Atlantic coast 

 in the latitude of the Grampians, cultivation stops at about 400 ft., 

 the fruticose Eubi at 500 ft., and Pteris with an average of 1250 ft. 

 on the south side of the hills ; but it would surely be a mistaken 

 use of terms to say that the climatic zone is lower here than in the 

 East Highland range of mountains, even allowing for the humidity 

 of the west coast being more favourable for arctic plants than is the 

 drier eastern side of the country. It is, I think, almost entirely a 

 condition of the surface of the land, the hills alluded to on the west 

 coast being only about 3000 ft. high, and devoid of table-land. 

 This usually implies that one side at least of the hills will have 

 steep rocks suitable for alpine plants down to a lower level than 

 occurs in a table-land district such as the Grampians. 



Although Watson characterizes his zones by the presence or 

 absence of certain plants, they are in reality "zones of temperature," 

 as they are named by Baker in his Flora of the Lake District ; and 

 I think that the term "ascending" is preferable to "climatic" as 

 applied to them, because the hills of Britain are not of sufficient 

 height to allow us to judge of the relation between plants and 

 climate in the arctic zone, even limiting the relationship to the 

 conditions as occur with us. The upper limit at which the majority 



