IV. PHYSICAL GEOGRAPHY. 137 



the purposes of this work. One exception must be made 

 to the provincial boundaries in tracing out this line ; the 

 sub-province of West Channel being thrown into the 

 western division of the island ; while the two other sub- 

 provinces of the same primary province are kept on the 

 eastern division. Again, the far western extension of 

 Yorkshire, even beyond the proper eastern water-shed, 

 brings the province of Humber too near the western 

 coasts for geographical correctness. Through this undue 

 comital extension, some western localities are reckoned 

 as eastern in the Census list of species ; and they are 

 also taken into account as eastern in the Summary of 

 Distribution. Several other such anomalies as this one 

 might be found in the map, but practical convenience 

 rendered a close adherence to county boundaries, as 

 before remarked, the paramount consideration in tracing 

 provinces. 



Almost the whole of Scotland is situate to the west- 

 ward of the longitudinal line which bisects England. 

 Though the line oi Four West divides Scotland into two 

 somewhat equal halves, that line also fails to separate the 

 western from the eastern coasts ; portions of each falling 

 on the wrong side of the line. In order to continue our 

 wavy dividing line northwards, we must trace it along the 

 western borders of the East Lowland and East Highlaiad 

 provinces ; that is, more in accordance with the water- 

 shed than with the mathematical line of longitude. As a 

 comital and provincial boundary, the line is arrested at 

 the North Highlands, through the extension of that pro- 

 vince and its counties from the eastern to the western 

 coasts. Geographical position, climate and plants, and 

 numerical convenience subsequently to be explained, all 

 suggest that tlie North Highland province should be 



VOL. IV. 1' 



