ANIMAL LIFE IN THE GREAT DESERT. 247 



ANIMAL LIFE IN THE GREAT DESERT. 



By WILLIAM MAKSHALL. 



THE surface of the earth, with its division of land and water 

 its diversities of climate, and its various elevations, offers 

 to the world of plants as well as to animals a complexity of life- 

 conditions to which their organisms are compelled to adapt them- 

 selves if they would even exist. 



Few regions exhibit to so large an extent such even, uniform, 

 and original character, as that vast desert expanse which stretches 

 through southern Arabia and northern Africa from the Persian 

 Gulf to the Atlantic Ocean. This uniformity is the result of the 

 correspondence of the desert tract with the same degrees of lati- 

 tude, and of its never departing from the subtropical regions. 

 Since, also, the elevation of the land seldom greatly exceeds 

 3,000 feet, the temperature conditions, however much they may 

 vary in single places in the course of a day, are as a whole more 

 uniform than they would be in a similar tract running north and 

 south, and marked by important elevations. The midday heat 

 in the desert rises to over 120 Fahr., while at night the cold, in 

 consequence of the rapid radiation, sometimes makes itself very 

 unpleasantly felt, and in winter descends below the freezing-point. 

 More unfavorable to the development of animal life than the 

 temperature is the want of water, both running and standing, as 

 well as the absence of rain and dew. Sufficient water and a thin 

 surface soil are found only in the oases, which exercise an in- 

 fluence over the distribution of life like that of the presence 

 of the numerous islands in the great ocean. Even including the 

 oases, vegetation is very scanty ; the immense territory of .the 

 Sahara, with an area of upward of 2,500,000 square miles, harbors 

 only 5G0 species of plants ; while the Japanese Islands, having only 

 one seventeenth the area, 150,000 square miles, support not less than 

 2,745 species. Most of the desert vegetation is deficient in quality 

 as well as quantity ; the plants are sparse, generally small, with 

 inconspicuous gray leaves, and often covered with sand. Many 

 plants that are usually annual develop, under the influence of 

 life in the desert, long roots reaching down to the ground water, 

 and become perennial. Monocotyledonous plants are represented 

 only by dry, tough grasses, like the esparto, and by a few palms 

 in the oases. Woods, the chief resorts of animal life, are wanting. 



Most of the scanty fauna is concentrated in the oases. The 

 oasis of Bachariel, according to the French entomologist Lefevre, 

 swarms with insects at certain seasons, which would yield a rich 

 harvest to the collector if he would stay there long enough to 



