46 VERTEBRATA. REPTILIA. 



readily be distinguished by an accurate examina- 

 tion. 



The harmless Serpents, or, more correctly, the 

 non-venomous, (for many of these are highly formid- 

 able from their vast strength,) have the upper and 

 lower jaws and the palate furnished with fixed and 

 solid teeth, so that there are four rows above and 

 two below. In most, the hind-head is much widened, 

 and the tongue forked, and capable of being thrust 

 out. 



Boa* 



This name has often been applied without much 

 precision to all Serpents of great size, but it pro- 

 perly belongs to those American species which have 

 the body and tail covered on the under side with 

 undivided plates, a hook on each side at the base 

 of the tail, a compressed body, thickest in the mid- 

 dle, a tail capable of grasping by twining round 

 bodies, and the hind head (and sometimes the whole 

 head) covered with small scales. The largest Ser- 

 pents are among the Boas, some, as the B. Constric- 

 tor,^ B. Scytale,% and B. Cenchris, frequently attain- 

 ing the length of thirty feet, and even more. They 

 are said to lie in wait near the outlets of the forest, 

 or at the drinking places ; and when a quadruped, 

 even of such size as deer, or wolves, (and, as has been 

 reported, but this is very doubtful, oxen and buffa- 

 loes,) approaches, they suddenly dart upon it, and 



* An ancient name of a large serpent. 



t Constringo, to bind together. J 2xtW, skytos, a scale. 



kenchris, the ancient name of some large serpent. 



