56 SAUEIA. 



THE ORDER OF LIZARDS— *S'^67?/.^. 



Anterior ribs generally jomed to a sternum. Tail more or less long. Jaws 

 toothed ; the mandibles united in front by an osseous suture. Limbs generally 

 f'jur, sometimes rudimentary or not visible externally. Eyelids generally present. 

 Integuments with scale-like folds or osseous scutes, or granular. 



By far the greater portion of the Saurians are easily distinguished from the other orders 

 of Reptiles by their elongate form, by their moveable thorax covered with skin, by the 

 presence of legs, and by their general integuments, which are either folded into scales, or 

 granular, or tubercular, or shielded. .Still, there are many Saurians which, at a superficial 

 glance, might easily be taken for members of the next order — that of the Snakes, and it 

 cannot be denied that there is a gradual transition between both these orders. On the 

 part of the Saurians, we allude to those which have no externally visible legs, and which 

 combine with a greatly elongate, cylindrical body, the peculiar kind of locomotion we 

 observe in Snakes. Yet the greater affinity of these reptiles to the Lizards is indicated by 

 another character which is in intimate connexion with their mode of life: — The Snakes, 

 having moveable maxillary bones, and mandibles not joined by a symphj'sis, are enabled to 

 swallow other animals of an apparently greater bulk than their own. In the Saurians the 

 maxillae are fixed and immoveable, and the mandibles are joined by an osseous suture, so 

 that the cleft of the mouth can be dilated only in a vertical direction, and not horizontally. 

 Moreover, in these limbless Saurians we always find bones of the shoulder hidden below the 

 skin, whilst no trace of them can be discovered in the true Snakes. The motions of some 

 Lizards are extremely slow, while those of others are executed with very great, but not 

 lasting, rapidity. 



Many Lizards have the power of changing their colours ; this depends on the presence of 

 several layers of cells loaded with different pigments ; the animal spreads or compresses these 

 layers by more or less inflating its lungs, whereby the changes in the coloration are effected. 



The tongue is differently shaped and has different functions in this order of Reptiles, 

 affording an excellent character for their subdivision. 



1. It is extremely short, flat, immoveable, and attached to the bottom of tlie mouth, with- 

 out special function (Crocodiles). 



2. It is slender, exsertile, and forked in front {Leptoglossw, Fissilingues) : a tongue of this 

 shape is eminently adapted for touching ; it is also used for cleansing the lips after the 

 animal has fed. 



3. It is short, thick, soft, attached to the gullet, and not, or but slightly, notched in front 

 [Pachyglossce, Crassilingues) : many Lizards with such a tongue are herbi\orous ; and we 

 cannot doubt that it is an oroan of taste. 



