192 



LIZAKDS. 



thoroughly snake-like ; its bod}^ is very long and slender, and it has 

 not the slightest appearance of limbs. Yet it is very closely allied 

 to the Lizards, as its internal structure clearly shows. The bones of 

 the pelvis, or arch to which the hinder limbs are attached, are found 

 to exist in a rudimentary state, although no outward indication of 

 limbs appears. If this little creature is laid hold of or alarmed, it 

 contracts its body so forcibly as to become perfectly stiff, and then 

 it will break in two with the slightest blow, or attempt to bend it. 

 We, therefore, at once perceive the propriety of one of its Latin 

 appellations, that of fragilis (brittle). The Slow-worm is not only 

 perfectly harmless, but extremely useful, its principal food consist- 

 ing of slugs, the greatest enemies of the agricultm-ist. 



In the Glass Snake of Nortli America the condition 

 of the limbs is equally rudimentary. Other species 

 display, as it were, links in a curious chain of gra- 

 dations ; some have two minute feet in front and none 

 behind ; others, as the Sheltopusik {Pseiidojms), have 

 only sproutings of the hinder pair. Some have both 

 pairs, but small and weak, set very far apart on the 

 lengthened body, and destitute of toes. In others, 

 they become gradually more developed, until we find 

 them at length completely formed, as in 



The True Lizards (Lacerta), remarkable for the 

 activity of their movements. Of these we have two 

 native species. 



The Common, or Viviparous Lizard (Zootoca), so called because 



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