VIVIPAROUS LIZARD; SAND-LIZARD. CHALCID.E. 563 



within them; and this is not improbably connected with the 

 unusual development which these animals subsequently attain, 

 in regard to the acuteness of their senses, and the activity of 

 their muscular movements. They burrow in the ground, and 

 retreat to their hiding-places on the slightest alarm. The 

 average length of this species is about six inches. The Sand 

 Lizard is larger than the preceding, its length varying from 

 seven to twelve inches ; two varieties of it appear to exist, 

 one being of a sandy-brown colour, and the other having a 

 mixture of green, more or less decided. The ordinary residence 

 of this species is on sandy heaths ; and though less quick and 

 active than the Viviparous Lizard, it runs with considerable 

 alertness. The greener variety, however, seems to frequent 

 more verdant localities. There is a beautiful green species, 

 nearly allied to the preceding, which is common in the south of 

 Europe, and which is frequently brought over to this country in 

 cages. It soon becomes very tame in captivity, and will take 

 flies from those with whom it is familiar. In all these Lizards 

 the tail is extremely brittle ; so that it snaps off at the slightest 

 touch, when the attempt is made to seize them by it. Nature 

 has provided a remedy for this accident, by giving to the ani- 

 mals the power of forming a new tail; this new organ has 

 only a central cartilage, however, in place of the bones, and is 

 often covered with scales different from those of the rest of the 

 tail. If the tail be cracked only on one side, and not thrown 

 off, a new tail often springs out of the crack, so that the mem- 

 ber becomes forked. Other Lizards have a similar power of 

 reparation. 



501. In the family CHALCID.E, we meet with a series of 

 forms, which presents us with a gradual transition from the order 

 of Lizards to that of Serpents, some of them, indeed, having 

 been placed by many Naturalists in the latter. The body is 

 usually cylindrical, and extremely elongated or snake-like ; 

 sometimes destitute of limbs, and mostly with the limbs only a 

 little developed : there is usually no distinct neck between the 

 head and trunk ; and the latter merges imperceptibly into the 

 tail. The accompanying figure represents the Four-toed Sau- 



002 



