128 MOSTLY MAMMALS 
with which is the great desert tract extending through 
Arabia, Syria, Mesopotamia, and Persia. By means of 
the more or less desert tracts of Baluchistan, Sind, and 
Kuch, this area leads on to the great Rajputana Desert 
of India. More important is the vast Gobi Desert of 
Mongolia, and other parts of Central Asia. In Southern 
Africa there is the great Kalahari Desert, of which more 
anon. In North America there is a large desert tract 
lying east of the Rocky Mountains, and including a great 
part of Sonora; while in the southern half of the New 
World there is the desert of Atacama, on the borders of 
Peru and Chili. Lastly, the whole of the interior of 
Australia is desert of the most arid and typical description. 
But among these there are deserts and deserts. Tracts 
of the typical barren, sandy type are, as already said, 
extensively developed in the Sahara, as they are in the 
Gobi and the Australian deserts. Between such and the 
plains of the African veldt there is an almost complete 
transition, so that it is sometimes hard to say whether 
a given tract rightly comes under the designation of a 
desert at all. A case in point is afforded by the South 
African Kalahari. Although there are endless rolling dunes 
of trackless sand, and rivers are unknown, yet in many 
places there is extensive forest, and after a rain large 
tracts could scarcely be called a desert at all. Mr. H. A. 
Bryden, for instance, when describing the Kalahari, writes 
as follows: “And yet, during the brief weeks of rainfall, 
no land can assume a fairer or more tempting aspect. 
The long grasses shoot up green, succulent, and elbow- 
deep ; flowers spangle the veldt in every direction; the 
giraffe-acacia forests, robed in a fresh dark green, remind 
one of nothing so much as an English deer-park; the 
bushes blossom and flourish; the air is full of fragrance ; 
