Reptilia. 199 



The Joint-snake. Every one has heard of the glass-snake or joint- 

 snake, which is by no means rare in the Central states. The commonjy 

 accepted story is that when struck it flies to pieces, and that the pieces 

 come together again, making the animal whole as before. The facts 

 are as follows : The glass snake is a lizard without legs, and with a tail 

 two or three times as long as the body proper ; hence it looks Very 

 much like a snake. A closer examination would show that it can shut 

 its eyes, which no snake can do. There is also a depression marking 

 the ear, not found in snakes. A groove along each side of the body is 

 also a feature never found in snakes. The tail is very brittle, as in all 

 lizards. When struck, the tail is easily broken off and broken into 

 several pieces, the short body usually crawling quickly away. No part 

 of the tail lives. The disappearance of the pieces of the tail is easily 

 accounted for by any one who knows how many animals are on the 

 lookout for something to eat. To one who knows the animal's struc- 

 ture an explanation is easy ; it is also easy to comprehend how the 

 ignorant usually accept the popular story. If one can be obtained, 

 carefully compare it with a snake. 



THE SNAKES. 



Characteristics of Snakes. The absence of limbs is not 

 distinctive, since the glass-snake is a legless lizard, and 

 some snakes have rudiments of hind limbs. In snakes 

 there are no movable eyelids, the eyes being covered by 

 the thin, transparent epidermis. The mouth is very dilat- 

 able, the lower jaw being held by extensible ligaments, 

 and the two halves of the lower jaw are also loosely con- 

 nected so they can be stretched apart during swallowing. 

 The tongue is long, soft, cylindric, and forked at the tip ; 

 it serves as an organ of touch, and has nothing to do with 

 the poison apparatus. The teeth are relatively small, 

 pointed backward, and serve to hold the prey and to aid in 

 swallowing. There is no breastbone. The number of 

 vertebrae is great, in the boa over four hundred. Ribs 

 begin on the second vertebra and continue the whole length 

 of the body cavity. 



