Page:Transactions of the Natural History Society of Northumberland, Durham, and Newcastle-upon-Tyne (1867).djvu/58

42 plants which he finds to be most characteristic; and of those which he names for the dysgeogenous strata, we have in Northumberland and Durham eight species only, whilst out of the eugeogenous fifty which are frequent in the arenaceous Vosges, but either nearly or quite absent in the calcareous Jura under parallel, or nearly parallel, conditions of atmospheric climate, we have thirty-five species, which are the following:—

We have in this list most, or very nearly all, the very species which make up the gregarious swamp-heather-land vegetation of which we have spoken as covering, with us, such wide tracts of surface. Of the four kinds of rock—limestone, porphyry, slate, and sandstone mixed with shale, that in the North of England form hill-masses on a grand scale, there are none from which these plants as a class are excluded, though it is amongst the sandstones that the ericetal species especially attain their greatest luxuriance and frequency. To sum up the bearings of the subjacent rocks on plant-topography, as exercised with us, as compared with what takes place in Central Europe, we shall be safe