DIVISIONS OF REPTILIA. 245 



also is the nearly-allied Naja haje (Fig. 120) of Africa. Oth- 

 er venomous snakes of evil notoriety are the Death-adder 

 (Acanthophis tortor) of Australia, the Puff-adder ( Vipera in- 

 flata) of South Africa, the Homed Viper ( Cerastes cornutus) 

 of Egypt, and the Harlequin-snakes {Elaps), but many others 

 are equally dangerous. 



Oedbe hi. Laceetilia (Lat. lacerta, a lizard). — The third 

 order of reptiles is that of the Lacertilia, comprising all the ani- 

 mals which are properly known as Lizards, together with some 

 snake-like creatures, such as the Blind-worm. They are distin- 

 guished by the following characters : Usually there are two pairs 

 of well-developed limbs, but there may be only one pair, or all the 

 limbs may be rudimentary. In all cases, however, a scapular 

 arch is present. The vertebrae are usually hollow in front 

 (^occe?OMs), rarely hollow at both ends (amphicmlous). In no 

 living Lacertilian are the teeth lodged in distinct sockets. 

 The eyes are mostly furnished with movable eyelids. 



As a general rule, the animals included under this head 

 have four well-developed legs, and wotild, therefore, be popu- 

 larly called " Lizards." Some of them, however, such as the 

 common Blind-worm {Anguis fragilis) of Europe, 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 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. 



Of the snake-like Lizards, a good example is to be found 

 in the common Blind-worm or Slow-worm of Europe. It is 

 completely serpentiform, without any external indications of 

 limbs (Fig. 133), and it is quite harmless. It is remarkable 

 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. This same brittleness exists in the Grlass-snake ( Ophi- 

 saurus ventraUs) of the Southern States, in which also there 

 are no limbs. In other allied genera, there may be fore-feet 

 alone, or hind-feet may be present, or all four limbs exist in a 

 more or less rudimentary condition. In the true Lizards 

 {Lacerta), all four limbs are present in a weU-developed form ; 

 as seen in the common Green Lizard (X. viridis) of Europe. 

 The genus Lacerta is represented in America by the Ameivoe, of 

 which the Striped Lizard {Ameiva sex-lineata) of the Southern 



