Hurter — Herpetology of Missouri. 149 



take the space left by a lost tooth for a natural interval ; 

 if a tooth has fallen out, a distinct pit or depression is 

 left on the alveolar edge of the maxilla. In counting the 

 teeth the second inner row of loose teeth which are only 

 the reserve teeth must not be taken into consideration. 

 If the specimen is so hardened that it is difficult to open 

 the mouth it should not be forced open by prying, a pro- 

 cedure apt to ruin the teeth and break the lower jaw, but 

 the thick muscle at the corner of the mouth closing the 

 jaws should be cut through on both sides. If properly 

 done the specimen need show no outward sign of mutila- 

 tion. The maxilla after being dissected out and cleaned 

 should be placed in a small glass tube or vial and, pro- 

 vided with the same number as the snake, kept in the same 

 bottle. 



"The apial scale pits are usually distinctly visible un- 

 der a fairly good magnifying glass. In some cases, how- 

 ever, they are rather difficult to discern. When the pits 

 are not discovered at once the skin should be allowed 

 to dry and then viewed at different angles to the light. 

 The epidermis of scales of different parts of the body 

 should be examined. In very doubtful cases it may even 

 become necessary to remove some of the epidermis and 

 examine it under a more powerful lens." 



Dr. G. A. Boulenger has shown that the question 

 whether the haemal processes are present on the posterior 

 vertebrae, or not, can be easily ascertained by making 

 an incision along the belly in the posterior fifth of the 

 body, pushing aside the viscera and disarticulating the 

 backbone by bending the body dorsally. 



Artificial Key to the Genera of Non-Poisonous Snakes 

 of the State of Missouri. 



Anal plate divided. 



Dorsal scales more or less keeled. 



Rostral normal; not shovel-shaped or keeled. 



Three plates between the rostral and the eye. 



