^^O CLASS REPTILIA. 



fixed and not pierced. There are, therefore, four 

 ranges, pretty nearly equal of these teeth in the 

 upper part of the mouth, and two in the under.* 



Those among them which have the mastoidian 

 bones comprehended in the cranium, the orbit in- 

 complete behind, the tongue thick and short, re- 

 semble the double walkers, in the cylindrical form 

 of the head and body, and have been formerly united 

 with the snakes, in consequence of their small scales. 



These are, 



ToRTRix, OppeLf 



They are distinguished from the snakes, even ex- 

 ternally, because the scales of the range which pre- 

 dominates along the belly and under the tail are a 

 little larger than the others, and because their tail 

 is extremely short. They have but a single lung. 



Those which are known belong to America. The 

 most common must be 



* The common opinion is that none of the serpents without fangs 

 pierced in front of the jaws is venomous, but I have some reason to doubt 

 this. They all possess a maxillary gland, often very bulky ; their back 

 molars frequently exhibit a furrow, which may well answer the purpose of 

 conducting some fluid. It is quite certain that many of these species, in 

 which the back teeth are very large, are considered excessively venomous 

 in the countries which they inhabit, and the experiments of Lalande and 

 Leschenauld seem to confirm this opinion. A repetition of such experi- 

 ments would be desirable. 



■|- These are also the Anilius of Oken, the Tobquatrix of Gray, and 

 the Ilysia of Hemprich and Fitzinger. 



