60 
ZOOLOGICAL EXERCISES, 
together that they cannot be separated, fill all the 
upper part of the spiral. Examine a portion of each 
with the microscope, and ascertain the sex of the 
individual. 
7. The reproductive organs.—The periwinkle 1s dicecious. 
In the male a convoluted vas deferens leads from 
the sex gland along the right side of the animal to 
the head. In the female the convoluted oviduct 
leads from the sex gland along the roof of the 
mantle cavity, outside the rectum, and opens near 
the anus. Try to make this out. 
8. The alimentary system—From the stomach trace 
forward the alimentary canal; follow it up, cutting 
open the body cavity and pinning back each side. 
In the head will be seen the large white buccal 
mass, with the cesophagus passing from it poste- 
riorly ; and the cerebral ganglia, connected together, 
lying on it. On each side of the cesophagus notice 
the delicate, white, salwary glands. 
9. Cut the cesophagus behind the nerve collar, and draw 
the anterior portion forward, through the collar, and 
cut out the buccal mass. Place it on a slide and 
notice the odontophore projecting outward from the 
inferior side. Open the buccal mass and extract the 
odontophore. Place this on a clean slide and examine 
with the microscope. 
10. Cut out the nerve collar, and place it on a slide. With 
a small brush lay it out in a drop of water ; cover it 
lightly, and examine with the microscope 
11. Examine a portion of the columellar muscle. It is 
unstriped. 
12. Cut off the operculum, and examine. 
