REPTILES. 



287 



them not unworthy of our attention. The changeable 

 lustre of many, especially of the tropical Lizards and 

 Snakes ; the elegance and grace of their movements ; the 

 provisions made for their defence in their formidable 

 weapons; peculiarities in their organisation whereby they 

 are fitted for their appointed spheres and habits; — these, 

 and many other details which our space forbids us even to 

 enumerate here, render the study of Jierpetology no less 

 attractive than any other branch of natural science. 



The Serpent may be considered as the characteristic 

 form of this Class of beings; at least, our thoughts more 

 spontaneously recur to the lithe and winding Snake, than 

 to any other shape, when the word Reptile is pronounced; 

 as, indeed, the idea of creeping* is most perfectly realised 

 in the gliding movements of an animal absolutely without 

 limbs- 

 There is something exceedingly interesting in this very 

 action. The rapid gliding of a Snake is performed by 

 means of the numerous ribs (which in the skeleton look 

 like the feet of a Centipede), and the broad plates (scuta) 

 which go across the belly. The action and the discovery 

 of its nature are described by Sir Everard Home in the 

 following words: — " When the Snake begins to put itself 

 in motion, the ribs of the opposite sides are drawn apart 

 from each other, and the small cartilages at the end of 

 them are bent, upon the upper surfaces of the abdominal 

 scuta, on which the ends of the ribs rest ; and, as the ribs 

 move in pairs, the scutum under each pair is carried along 

 with it. This scutum, by its posterior edge, lays hold of 



* The -words herpetology. reptile, serpent, creep, have all one derivation ; 

 epTrco is their common parent. 



