AMPHIBIA 199 



glassy or vitreous humor filling the posterior chamber of 

 the eye. The ear composed of the three semicircular 

 canals opening into the oval sac, called the vestibule, may be 

 seen in part by shaving off the side of the skull in the pos- 

 terior part. 



16. AMPHIBIA 



The Amphibians, often called Batrachians, derive their 

 name from the fact that many of the species live a part 

 of their life on land and breathe by lungs, while the other 

 part is spent in the water where gills must be used. The 

 members of this class are distinguished from both the fish 

 and the reptiles by the absence of scales. They are divided 

 into three orders, the Urodela, Anura, and Gynmophiona. 





FIG. 228. Photograph of newts nearly natural size. 



