58 baker's north YORKSHIRE. 



flora more varied and more southern. As determining differ- 

 ences between the floras of Umited tracts the results of this 

 difference may be traced, but throughout the various parts of 

 our low country the different kinds of soil are so much mixed 

 up together that as regards its application to the topography of 

 our vegetation this is all the result that can fairly be attributed 

 to it with clearness. 



The most prominent contrasts concerning topography of vege- 

 tation of which we have to speak are in the first place the restric- 

 tion of a category of specially Xerophilous or dry-loving species 

 to the dysgeogenous soils in such a way that this restriction is 

 one of the most prominent features of their role of distribution ; 

 and in the second place as regards the modification which the 

 influence of the subjacent rock exercises upon the altitudinal 

 range of certain species. Though to a certain extent It involves 

 the repetition of what has been already dwelt upon, I will quote 

 from my note-book, in order to connect together more clearly 

 what follows with what has been stated already, two extracts 

 which give an account of excursions made to hills of the two 

 lithological types and which enumerate also the commoner or 

 more conspicuous plants which the two hill-surfaces and their 

 slopes produce. 



' The Harriet Air near jRievaidx, a?id Ouldray Gill. — A plateau 

 with the beds of limestone rock not far from the surface, covered 

 with elastic wiry grassy turf, the constituent elements of which 

 are the common plants of pastures, but scattered over with 

 Carlina and Bee-orchis, and with Thyme and Rock-rose and 

 Poterium Sanguisorba in knolls upon its undulations, and a few 

 scraggy bushes of Hawthorn and a few blocks of hard massive 

 calcareous gritstone scattered over its slope in the direction of 

 the main dale. 



The plateau is about 600 feet in elevation above the sea-level, 

 and there are two or three farm-houses upon it, with Sycamore 

 and Scotch Fir planted to shelter them from the moorland 

 breezes, and there are fields of Oats and Rape and forage,. 



