Page 230 - Third Book of Reading Lessons

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READING LESSONS. 229
of the extremity which would otherwise touch the ground, blunts the power of tact, and renders such extremity incapable of seizing anything. The oppo­ site extreme to this is, when a nail rms a single lamina on one side of the end of the nger or toe only, leaving to the other all its sensibility.
4. The nature of the diet ay be judged of by the cheek-teeth, to the rm of-which the articulation of the jaws invariably corresponds. For cutting esh, the cheek-teeth are trenchant like a saw, and the jaws are tted together so as to move in the manner of a pair of scissors, and are incapable of any other mo­ tion than that of simply opening and closing again in a vertical direction. The cheek-teeth adapted r the mastication of grains or roots, have a attish round upper sur ce, or rather the shape of a at coronet; and the jaws possess the capacity of hori­ zontal motion. That the sur ce of such cheek-teeth should keep that sort of inequality peculiar to a mill­ stone, their substance is composed of unequal hard­ ness, some of which parts wear sooner than others.
5. The hoo d animals are all of necessity herbiv­ orous, and possess teeth of this description, because the con rmation of their et will not permit them to seize a living prey. Animals with unguiculated or clawed ngers or toes are susceptible of great va­
riations in their modes of subsistence. Independent-
ly of the rm of the cheek-teeth, these animals i er materially among themselves in the power of touch, and the cility with which the ngers and toes can be put in motion. There is one characteristic which has a prodigious in uence on the dexterity of the an­ imals possessed of it, and multiplies greatly, or va­ ries, its modes of action. It is the culty of oppos-
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