313 



AMPHIBIA. 



ORDER 



SERPENTES. 



__ HESE animals are sufficiently distinguished 

 from the preceding tribes of Amphibia by their 

 total want of feet, moving by the assistance of 

 their scales, and their general powers of contor- 

 tion. 



The distinction of species in this numerous tribe 

 is often peculiarly difficult. Linnxus persuaded 

 himself that an infallible criterion might be found 

 in the number of scaly plates on the abdomen and 

 beneath the tail; and, accordingly, attempted in 

 the Sy sterna Naturae to discriminate the species 

 by this mark alone : experience, however, has suf- 

 ficiently shown that, though often highly useful 

 in the investigation of these animals, it is yet 

 by much too uncertain and variable to be per- 

 mitted to stand as an established specific test; 

 and it is to be lamented that Linnaeus should 

 have so little availed himself of other more ob- 



v. in. P. ii. 2i 



