REPTILES. 
287 
them not unworthy of our attention. The changeable 
lustre of many, especially ol 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 herpetology 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 wiuding 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 Snako is performed by 
means of the numerous ribs (which in the skeleton look 
like the feet of a Centipede), aud the broad plates (scuta) 
which go across the belly. The action and the discovery 
of its nature arc 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 : 
eprrco is their common parent. 
