270 



VERTEBRATE ANOtALS. 



tiliaii are the teeth lodged iu distinct sockets. The eyes are mostly 

 furnished with movable eyelids. The integument is usually fur- 

 nished with horny overlajijiing scales, like those of the Snakes 

 (fig. 19.5). 



As a general rule the animals included under this head have 

 foiu- well-developed legs, and would therefore be popularly called 

 " Lizards." Some of them, however, such as the common Blind- 

 worm {Anr/iiis fragilis) of our own country, exhibit no external 

 indications of limbs, and would therefore be generally regarded as 

 Snakes. These snake-like Lizards, however, can be distinguished 

 from the true Ophidians by the consolidation of the bones of the 



Fig. 195.— Blind-worm (.l«9tlis/TOgi?is). (After Bell.) 



head and jaws, and by the fact that the eyes are generally provided 

 with movable eyelids. Dissection also shows that the shoulder- 

 girdle (or scapular arch) is always present in a rudimentary 

 condition. 



Few Lizards are natives of Britain ; the only forms which can be 

 said to be at all abundant being the Blind-worm or Slow-woim and 

 the Sand-lizard {Lorerta af/ilis). Of the snake-like Lizards, a. good 

 example is to lie found in the common Blind- worm or Slow-worm 

 of Europe. It is completely serpeiitiforni, without any external in- 

 dications of limbs (fig. 195), and it is quite harmless. It is remark- 

 able for the fact that, when alarmed, it stiffens its muscles to such 

 an extent that the tail can readily be broken off, as if it were brittle. 



