462 LAND ANIMALS 



(Meloidae), which predominate in steppe regions. 59 Finally, several 

 families of beetles occur in large numbers in open country. Correlated 

 with the abundance of ungulates, the dung beetles appear, finding 

 abundant food for themselves and their brood. Numerous and varied 

 forms of tenebrionids range wherever there is bare ground and loose 

 sand, and are abundant in dry, hot regions; South Africa alone has 

 more species of them than all tropical America; the Near East and 

 central Asia have more than the Indo-Malayan area ; of the 48 species 

 of beetles, for example, which Escherich 60 collected on the island of 

 Djerboa (Tunis), almost half belonged to this family. Insects of the 

 remaining orders are of less importance in comparison with these and 

 are for the most part scarce on the grass floor because of their monot- 

 onous plant covering, the more so, the closer the area approaches 

 desert conditions. 



A peculiar group of animals limited to arid steppes and desert 

 regions is composed of the agile spider-like solpugids, which are found 

 in suitable localities in Eurasia, the whole of Africa, and subtropical 

 North America up to Colorado. They prey upon insects, mostly ter- 

 mites, but do not reject even small vertebrates. True spiders and 

 scorpions are not absent, but are less distinctive of the arid, open lands. 



Vertebrates of the steppes. — The open country is the domain of 

 the reptiles. Favorable living conditions are offered for these warmth- 

 tolerant animals, which expose themselves to the direct rays of the 

 sun and thereby raise their internal temperature to the optimum of 39°, 

 corresponding to the temperature of homoiothermic animals, and in- 

 hibit a further rise by increased respiration or by burrowing. Lizards 

 and snakes are present in large numbers of species and individuals in 

 the grasslands; although they are not common everywhere, they occur 

 in places in large numbers; the turtles are less common. Many reptiles 

 are fossorial, and dig into the ground or at least make use of burrows 

 already present. Sandy soil readily permits them to burrow, and they 

 are especially numerous on such terrain. The food of lizards is pri- 

 marily insects; only the largest species, such as the monitors, also 

 capture vertebrates. In the cold steppes, the reptiles hibernate; but in 

 the subtropical regions, many remain active all the year around. They 

 form one of the chief sources of food for carnivorous mammals and 

 birds; jackals, civets, mongooses, and other predators feed on lizards 

 and snakes; and marabous, storks, hawks, the secretary bird (Sagit- 

 tarius) , and other birds may live primarily on them. 



The abundance of insects, reptiles, and small rodents, and immense 

 numbers of various seeds make favorable feeding grounds for birds. 

 Unobstructed view is important for them as eye-dependent animals; 



