Reptilia. 97 



wide ventral plates below ? It is usually easier to keep the count 

 by following the row of scales obliquely across the body. 



Use Jordan's Manual of the Vertebrates for finding the names 

 of any reptiles found in your vicinity. 



DISSECTION OF A SNAKE. 



Get a large snake, a paper of tacks, and a board as long as 

 the snake. The board should be of dressed soft pine so that the 

 tacks may be inserted by the thumbs ; a hammer should be un- 

 necessary, tho if the spinal cord is not destroyed, the body may 

 pull with considerable force, and it may be desirable to drive a six- 

 penny nail firmly through the tail just back of the anus. Lay the 

 snake on its back, with the head at one end of the board. Push the 

 point of a tack into the mouth at one side, and drive it through the 

 upper jaw, leaving the lower jaw free. Repeat with the other side. 

 Stretch the snake out straight, and tack through the tail, just back 

 of the vent. With the forceps pinch up a fold of the skin of the 

 throat, and cut through it with the scissors. The greatest danger is 

 that of cutting into the air sac, which, when distended, fills most of 

 the space of the body cavity. To guard against cutting into it push 

 the handle of a small spoon, or the bowl of an " after-dinner coffee 

 spoon," along under the skin ahead of the scissors so the lower 

 point of the scissors shall be constantly guarded. Continue the cut 

 back along the middle line of the ventral wall, being very careful 

 not to cut anything within. As the cut proceeds, stretch the skin 

 out at the sides, and tack it down every two or three inches. Cut 

 away the thin membrane which extends across from the ribs on 

 each side, avoiding blood tubes. 



1. With forceps seize the lower jaw and pull the mouth open. 

 Note how dilatable the mouth is, and how loosely the lower jaw is 

 hinged to the upper ; note, also, that the right and left halves of 

 the jaws do not unite in front. Examine closely the teeth, their 

 shape and arrangement. In what direction do they point? 



2. Seize the tongue, and draw it forward from its sheath in the 

 floor of the mouth. Observe its black, forked tip. 



