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MEMOIR OF THE AUTHOR. XV 



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in which province that particular species grows. For fuller 

 detail, to be used in local work, these provinces were afterwards 

 subdivided into 38 subprovinces and 112 counties or vice- 

 counties. The vertical range of the species he registers by 

 means of two regions of climate and altitude, each divided into 

 three zones. The Agrarian region includes that part of Britain 

 in which it is possible, so far as climate is concerned, to cultivate 

 the cereal grasses and potatoes. It of course includes the whole 

 area of the island at sea-level from north to south ; and the 

 hills up to about 600 yards in the North of England, and 400 

 yards in the North of Scotland. All above this is mountain, 

 heather, and rock, with a tempera ture like that of the low levels 

 in Arctic latitudes. This upper region he called the Arctic 

 region, and the zones Superarctic, Midarctic, and Inferarctic, 

 Superagrarian, Midagrarian and Inferagrarian. The Infer- 

 agrarian zone, for instance, includes all the low-level country 

 south of the estuaries of the Humber and the Mersey. He 

 estimated that average annual temperature sinks at the rate 

 of one degree Fahrenheit for every hundred yards of elevation, 

 and that in Britain the range of mean annual temperature is 

 from 52 to 34, which makes a zone to be equal on an average 

 to three degrees of Fahrenheit's scale. Then he deals with each 

 species from a historical point of view, classifying them into 

 Natives, Colonists, Denizens, and Aliens, according to whether 

 they appear to have come into the country without man's help, 

 or to have been introduced by human agency, acting directly or 

 indirectly. And finally he separates out the species into their 

 types of distribution, British, English, Atlantic, Germanic, 

 Scotch, or Highland, according to whether they preponderate in 

 some particular part of the island or are dispersed, broadly 

 speaking, through the whole of it. In a ' Supplement of the 

 Cybele,' which came out in 1860, the horizontal range of the 

 species is traced out through the thirty-eight subprovinces. In 

 the three volumes of the ' Compendium ' (1868-1870) a mass of 

 additional information obtained after the publication of the 



