404 



REPTILIA— ORDER ni.—SQUAMATA. 



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

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

 Ignanidce, 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 defined 

 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 lyuanidte, the teeth are pleurodont, and the bases of 

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

 cally from beneath. In the three genera Zmiurus, Psendocm-dyhis, and 

 Platysau7~us, both pairs of limbs are well developed, but in Chairuesaiira, 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 max'ked than inthe family typically represented 

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

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

 applicable. While all these lizards resemble the members 

 of the preceding family in having the liinder 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, iiistead 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 



Snalre-like 



Lizards. — 



Family 



Anguidce. 



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 Hclodermatida. 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, 

 ivhen 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 shagijy papillai, and a small thin emarginate front moiety, 

 of which the covering talccs the form of small, scale-like papilte. This front 

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



F'uj. 10.— Blind-Worm (Anguis fragilis). 



