452 



LAND ANIMALS 



and much of the interior of Australia, and in South America, a narrow 

 strip between the mountains and the Pacific in Chile and Peru, to- 

 gether with isolated smaller desert areas on the eastern slope of the 

 Andes. 



The steppes are even more varied in type than the savannas. They 

 are found in subtropical as well as temperate climates, at low levels 

 as well as at high altitude. The vegetation does not attain the luxuri- 

 ance of the savanna grass areas; all gradations are present, from knee- 

 high to a short grass, which may even be broken by more or less wide 

 stretches of bare ground. With the grass are found many kinds of 

 flowering plants, plants with root bulbs, poppy, thistle, and Artemisia, 

 which may predominate. Where such flowering plants are wanting, 



Fig. 120. — Skull of a hare, with abnormally elongate molars, due to lack of use and 



wear. 



one naturally misses their boarders, the pollen feeders and nectar- 

 sucking animals such as bees, butterflies, hawk moths, and noctuids. 

 In many steppe areas, e.g., in the South African or Asiatic steppes or in 

 the Argentine pampas and in the western United States, there are 

 stretches where the soil is rich in common salt and supports only a 

 sparse growth of halophytes. 



On the plains the abundance of animal life depends directly on the 

 density of the vegetation, all parts of which serve animals as food, 

 whether they are just sprouted young seedlings, ripe, hardened stems, 

 dried, stiff, and often thorny stalks, leaves, seed, and fruit, or roots 

 and tubers. But to work up such food, strong masticating apparatus 

 is necessary. Locusts and termites possess powerful, efficient mandibles. 

 Rodents and the ungulates are equipped with front teeth fitted for 

 clipping vegetation and have strong molars with broad roughened 

 crowns for grinding; in rabbits (Fig. 120) and horses, these rear teeth 

 are adapted for long, heavy use by the capacity for continued growth. 

 Kangaroos employ their lower incisors like a pair of scissors. The 



