MECHANICS OF SNAKES — LEUTSCHER 309 



python can swallow a fair-sized deer and a grass snake can engulf 

 a frog that is twice the diameter of its own head (pi. 3) . 



The egg-eating snake {Dasypeltis) is capable of tackling a hen's 

 egg, which is eaten whole. Certain of its vertebrae have enameled 

 tips projecting into the gullet. These crush the egg in its passage 

 toward the stomach. The contents arc swallowed and the eggshell 

 regurgitated as a pellet. 



A typical snake's tooth in its layer of enamel is recurved and 

 sharply pointed. It is used only for gripping food. Having no 

 socket, an ordinary tooth is easily broken off but soon replaced; re- 

 serve teeth grow from the gums lining the inner side of the jaw and 

 move into position after each accident. 



In some serj^cnts certain teeth are modified into poison fangs. 

 These are larger than the normal teeth but retain the general pat- 

 tern of prehensile teeth. They are used, however, for injecting the 

 poison, which is produced in one or other of the modified salivary 

 glands. As with normal teeth they easily break off, and one method 

 of defanging a snake is to allow it to strike at a cloth, which is then 

 jerked away from the closed mouth. But again, a reserve tooth can 

 grow into position and replace a fang that has been lost. 



In the venomous snakes of the large family Colubridae, in which 

 the long maxillary bone is fixed, the fangs may lie at the rear end 

 of this; hence the name of their division, the Opisthoglypha. The 

 fangs are usually too far back in the mouth and the poison too weak 

 to make these snakes a real danger to man. The Montpellier snake 

 {Malpolon monspessulanus) is of this kind. A specimen that once 

 hit me on the bare arm caused no further discomfort than the pain 

 of the lacerated skin. On the other hand, one of similar length, 

 about 2 feet, bit and killed a grass snake in my reptiliary. 



It is among their cousins, the division Proteroglypha, or front- 

 fan ged snakes, that we meet the killers. Such are the cobras, kraits, 

 and mambas. Many of them bite with a bull-dog tenacity ; they tend 

 to hang on and force their fangs into the flesh with a chewing action. 

 The result is often a severe laceration, and this may be accompanied 

 by much loss of poison as it leaks out of the wound. Both groups, 

 front-fanged or back-fangcd, have permanently erect fangs in the 

 fixed maxillary bones. 



The whole operation is in many cases a clumsy affair and not 

 always as swift as one imagines. A rearing cobra may look a fear- 

 some sight, yet some people will approach and tease it with impunity. 



Far more efficient and less wasteful is the poison mechanism of the 

 family Viperidae, which include the Old World vipers and the New 

 World rattlesnakes. Here the maxillary bones are short and so placed 

 tliat they can rotate on their front axes where they join the prefrontal 



