19 
THURSDAY, APRIL 10rx. 
Che Zones of the Chalk near Brighton, 
WITH AN 
Introductory Sketch of the Existing Zones of Life 
in Britain, 
BY 
Mr. WILLIAM McPHERSON, F.G:S. 
‘lid order to make perfectly clear what is meant by the terms I 
have used, “ Zones of Life,’ I shall begin with an example 
of the application of the term to existing conditions of life,— 
Animal and Plants. This will enable you better to understand 
the significance of the zones in the chalk, to the determination 
of which I have devoted the last four winter and early spring 
months. 
The term Zone, as used in this Paper, is an arbitrary 
Horizon of Life. They more or less overlap each other, and the 
animal or plant chosen to represent the zone is one that has a 
small vertical range; and where they are most prolific, they 
encroach upon the zones above and under, but in diminished 
numbers. . 
I have selected the game birds and animals of Britain and 
their characteristic food plants, as they represent very distinct 
and well-defined zones, from the highest mountains down to the 
sea level. Latitude in Britain affects the zones ; for example, 
the red deer is found in Inverness-shire at an elevation of 1,200ft. ; 
in the Island of Lewis in the outer Hebrides it comes down to 
200ft. Everywhere we find an adaption to their surroundings, 
in regard to altitude, latitude, and temperature. Moisture and 
cold play important parts in the distribution of life. Moisture 
in temperate latitudes, with its increase of vegetable food, where 
the monthly rainfall is fairly equally distributed, produces a 
greater number and variety of genera and species of animal life 
than is found in warmer climates with an irregular rainfall. 
Beginning with the highest zone of life in Britain, that of white 
hare and ptarmigan. The white hare (Lepus albus) inhabits the 
upper parts of the mountains of central Scotland. It was formerly 
found in Cumberland and Westmoreland, but is now extinct in 
