358 GENERAL ZOOLOGY 



enough to swallow animals greater in diameter than itself. 

 The passage of food into the esophagus is facilitated by an 

 abundant secretion from salivary glands, and escape of the 



^~~ _.„j prey is prevented by the 



s " : ^^^^^^&~; - 4 sharp, backward-pointing 



5 TT^^?§^#I^ teeth in both jaws. The 



6 ^ J^J/ union of the two sides of 



£^fj^ the lower jaw in front is 



so loosely made by a 



^^^^^yjj^^- cartilaginous connection 



s ifl^^^^^^KvS^v"^ 7 '"" 7 ^ that each side of the jaw 



^^^&^PR^?>g^ can ^ e pushed forward 



6 ^ ^J^W^>^^S independently, thus get- 



^^^^0^^ ting a fresh hold on the 



7 ^g^^ food. Some of the larger 



^r-^^^%v snakes, as the pythons 



10 .^^JgjjjJHJg ^-~m and boas, kill their prey 



r^^^^x . N ^^i^P^ by constriction : the non- 



\a\ x •'' poisonous species may 



6 :Sk •" swallow theirs alive ; the 



12 J\ poisonous species gener- 



Fig. 184. Skull of rattlesnake, showing ally kill the animal, un- 



poison fangs » j ess j t be a small one. 



I, 2, bones of cranium ; 3, prefrontal bone ; J n captivity many of 

 k, quadrate bone; 5, maxillary bone; . , 



6, fang.; 7, bones of lower jaw; s, tip of the large snakes refuse to 



snout; 9, poison gland; 10, poison duct; ea t. In zoological gar- 



I I, reserve fangs; 1 2, tip of fang; 13, tern- , ., , , 



porai muscle dens tne extremely large 



pythons are held by sev- 

 eral men and a whole animal as large as a rabbit is poked 

 down the throat with a probe. 



Snakes crawl by means of muscles attached to the ribs 

 and scales of the under side. These scales have a free 

 posterior edge, which can be inserted into rough places. 



1 From Baskett's Story of the Amphibians and Reptiles. 



