404 



REPTILIA ORDER HLSQ UAMA TA. 



interclavicle being cruciform instead of T-shaped ; while, from the latter, it 

 is differentiated by the conformation of the tongue which, as in the 

 IgiianidcK, is not divisible into an interior and posterior portion as well as 

 by the hollow bases of the teeth, and by the structure of the bony plates, 

 which in one genus underlie the scales. All have a fold of skin covered with 

 small scales along the sides of the body, by which the upper surface is denned 

 from the lower* The head is invested with large and regular shields ; but 

 the back may be covered either with shield-like scales, which are frequently 

 provided with keels, and are arranged in regular transverse zones, or with 

 granules. As in the Jgpuant&Bj the teeth are pleurodont, and the ba,ses of 

 those in use are hollowed out by the tips of their successors, which rise verti- 

 cally from beneath. In the three genera Zonurus, Pseiidocordylus, and 

 Platysaurus, both pairs of limbs, are well developed, but in Chamcesaura, the 

 general form is snake-like, the fore-limbs being absent, and the hind ones 

 rudimentary, while the tail is remarkable for its excessive relative length. 

 The only Malagasy form is a species of the genus first named. 



Although in several groups of the sub-order the limbs have more or less 



completely disappeared, in no case is the assumption of a serpent-like form 



more strongly marked than in the family typically represented 



Snake-like by the common British blind-worm. It is to this family, 



/Lizards. accordingly, that the name of snake-like lizards is most 



Family applicable. While all these lizards resemble the members 



AnguidcK. of the preceding family in having the hinder lateral regions 



of the skull roofed by bony plates developed in the deep 



layer of the skin, they differ in the structure of the teeth, It is true that 



the teeth are often attached in the pleurodont manner, but instead of having 



the base hollow, this is solid, the new teeth coming up between two of the 



old ones, instead of beneath the crown of the one immediately above.- Whereas 



in most of the genera the teeth are either tubercular or in the form of short 



cones firmly attached to the sides of the jaws, in the blind- worms they are 



long, slender, highly curved, and 

 very loosely fastened to the bone. 

 In these respects the blind-worms 

 come very close to the snakes, and 

 also to the poisonous lizards of the 

 family Helodermatidce. And it is 

 not a little remarkable that traces of 

 a groove have been detected along 

 the front surfaces of the teeth of 

 the blind-worms which appear to 

 correspond to the poison-grooves of 

 those of the family in question. It 

 seems, therefore, as if the popular 

 dread of the blind-worm was in- 

 stinctive, and that the creature is either descended from poisonous ancestors, 

 or would be poisonous if it could. All the members of the family have bony 

 plates developed in the deep layer of the skin beneath the scales, these plates, 

 when viewed under the microscope, displaying a system of canals. Very 

 peculiar is the tongue, which is divided into a large thick hinder portion, 

 thickly covered with shaggy papillre, and a small thin emarginate front moiety, 

 of which the covering takes the form of small, scale-like papillae. This front 

 portion is extensile, and also capable of more or less full retraction into a 



Fig. 16. BLIND-WORM (Anguis fragilis). 



