142 INTRODUCTION TO ZOOLOIJY. 



THE SNAIL. 



1. The pointed end of the shell is the apex. 



2. The large opening is the aperture. 



3. The edge of the aperture is the lip. 



4. Find the lines of growth, parallel to the lip. 



5. Find the spiral groove, on the outside, running 

 to the apex. This groove is called the suture. 



6. Observe the turns of the shell between the 

 grooves. These are called whorls. 



7. The whorls, all taken together, excepting the 

 largest, or body whorl, constitute the spire. 



8. The axis, around which the whorls are coiled, is 

 called the columella. 



9. Hold the apex up, the aperture toward you. If 

 the aperture is toward your right hand, it is a dextral, 

 or right-handed shell. If the aperture is toward your 

 left hand, it is a sinistral shell. 



10. If the snail has a lid to close the aperture, the 

 lid is called the operculum. 



11. Break off the shell and see the body. Find 

 the foot, the head, the mantle, the tentacles, and the 

 mouth. 



12. Notice the shape of the body. You may see 

 from the outside some of the digestive organs. The 

 liver is the largest. 



&" 



The Live Snail. 



1. Watch live snails crawling over the sides of a 

 glass jar. Can you see tentacles? Eyes? 



2. See the mouth, as it opens and shuts. How does 

 the snail eat? 



3. Can you find the opening through which air is 

 taken into the lung, or water into the gill? 



4. How many kinds of snail shells can you 

 collect? 



