. Beginners' Zoology . According to the usual rule, they tended toincrease faster than the food supply, and therewere continual contests for food. Those whoseclaws and teeth were sharper drove the othersfrom the food, or preyed upon them. Thus thespecialization into the bold flesh-eating beastsof prey and the timid vegetable feeders of the flesh eaters has already been stud-ied at The insectivora escaped theirenemies and found food by learning to burrowor fly. The rodents accomplished the same result either byacquiring great agility in climbing, or by living in holes, orby
. Beginners' Zoology . According to the usual rule, they tended toincrease faster than the food supply, and therewere continual contests for food. Those whoseclaws and teeth were sharper drove the othersfrom the food, or preyed upon them. Thus thespecialization into the bold flesh-eating beastsof prey and the timid vegetable feeders of the flesh eaters has already been stud-ied at The insectivora escaped theirenemies and found food by learning to burrowor fly. The rodents accomplished the same result either byacquiring great agility in climbing, or by living in holes, orby running. The proboscidians acquired enormous sizeand strength. The hoofed animals found safety in flight. Orohippus, Fig. 383. -Feet of the ancestors ofthe horse. 212 ^^tr ^... -^.^ BEGINNERS ZOOLOGY. Fig. 384- — Tapir ofSouth America {Tapirus atnericanus). x ^. Questions: How does it resemble an elephant? (Fig. 376.) Ahorse? (p. 210.) Ungulates, as the horse, need no other protection thantheir great speed, which is due to lengthening the bones of the legs and risingupon the very tip ofthe largest toe, which,to support the weight,developed an enor-mous toe-nail called ahoof. The cattle, nothaving developed suchspeed as the horse,usually have hornsfor defence. If a calfor cow bellows with distress, all the cattle in the neigh-bourhood rush to the rescue. This unselfish instinct tohelp others was an aid to the survival of wild cattle livingin regions infested with beasts of prey. Which of ^sopsfables is based upon this instinct ? The habit of rapidgrazing and the correlated habit of chewing the cud werealso of great value, as it enabled cattle to obtain grass hur-
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