20 Mammals of Eastern Asia 
blows from the southwest from May to October. Most of this 
moisture is deposited upon the coastal mountains of Arakan 
and the highlands of Assam, with relatively little falling in the 
interior of the country north of Prome. Parts of Arakan receive 
as much as 200 inches of rain annually, while the interior "dry 
zone" has only about 50 inches, though the mountains beyond 
along the Yunnan frontier receive nearly as much rain as the 
Arakan Hills. At sea-level, in the deltas of the Irrawaddy and 
the Salween Rivers where the protecting influence of the Arakan 
Hills is not felt, the rainfall is also abundant, about 100 inches. 
Animal Environments and Faunal Areas in Eastern 
Asia (fig. 3). The sum total of the conditions under which an 
animal lives constitutes its environment. Although environment 
is more comprehensive than climate, local climate is always an 
integral factor of environment. Environment is influenced also 
by the physical and chemical character of the land and soil, 
whether the locale is mountainous, rocky, swampy, sandy, acid 
or alkaline. If an organism is aquatic, the character of the water 
is important, whether a lake, a sluggish river, a mountain tor- 
rent, sweet or brackish, hard or soft. Another factor that plays 
an important part in an animal's environment is the character 
of the local vegetation. Is the land forested, grass-covered, or 
semi-desert? If forested, is it composed of stands dominated 
by one or a few species of trees, like pine, spruce, oak? Or is it 
a mixed hardwood forest of oaks, hickories, beeches? Depend- 
ing upon its relationship to climate and soil, the forest may be 
tall and luxuriant, or low and seemingly starved. 
Forests of the tropics differ completely from temperate for- 
ests. One of the many reasons for this, and possibly the most 
important of them, is the ability of temperate and arctic plants 
to tolerate the extreme changes of temperature, compared with 
the intolerance of such by tropical plants. Accompanying those 
varying tolerances of temperature go other more local toler- 
ances : Both the tropical and the temperate zones contain certain 
