17*2 REPTILIA. 



ORDER II. 



SAURIA*. 



THE Saurian* have a heart like that of the chelonia, composed of two 

 auricles and a ventricle, sometimes divided by imperfect 

 partitions. 



Their ribs are moveable, partly connected with the 

 sternum, and rise and fall in respiration. 



Their lungs extend more or less towards the poste- 

 rior extremity of the body; it frequently penetrates 

 very far into the lower part of the abdomen, whose 

 transverse muscles pass under the ribs, and even 

 towards the neck, to clasp it. Those in which this 

 organ is very large, possess the singular faculty of 

 changing the colours of their skin accortling to the 

 excitement produced in them by their wants or passions. 



Their eggs are enveloped by a covering more or less hard, and the young 

 always retain the form in which they quit them. 



Their mouth is always armed with teeth, and their toes, with very few 

 exceptions, are furnished with nails ; their skin is covered with scales, more or 

 less compact, or at least with scaly granules. They all have a tail more or less 

 long, and generally very thick at base ; most of them have four legs, a few only 

 having but two. 



FAMILY I. 



CROCODILIDA. 



THIS family contains the single genus 



CROCODILUS, Brisson. 



Crocodiles are large animals, with a tail flattened on the sides, five toes 

 before and four behind, of which only the three internal 

 ones on each foot are armed with nails, all more or less 

 united by membranes ; a single range of pointed teeth 

 in each jaw ; the tongue fleshy, flat, and adhering close 

 to its edges ; a circumstance which induced the ancients 

 to believe that they had none; the back and tail 

 covered with very stout, large, square scales or plates, 

 relieved by a ridge along their middle; a deeply notched 

 crest on the tail, which is double at its base. The 

 plates on the belly are smooth, thin, and square. Their 



From ftfvfif. Lizard, animals analogous to Lizards. 



