90 ZOOLOGY DIEECTIOXS 



organ produces digestive fluids. At its inner end each cecum 

 is attached to the pyloric chamber of the stomach. 



4. Pyloric sac or stomach. Shape ? Position ? How at- 

 tached to body wall? How many and what openings from it? 

 Into it ? 



{Extensor muscles of rays. Situated in the center of the 

 lower face or aboral wall of each ray. What movement can be 

 produced by their contraction?) 



5. Cardiac division of the stomach. Remove the eeca from 

 two adjacent rays and under the corner of the pyloric sac note 

 one of the five cardiac pouches, the union of which makes the 

 cardiac stomach. 



6. Stomach retractor muscles. There are two to each 

 pouch. Attachments? What effect would their contraction 

 have ? Notes required. 



7. Esophagus. Cut two of the stomach retractors and 

 raise up the pouches so as to expose the esophagus. 



8. Persitome or membrane around the mouth. Expose 

 from inside. 



9. Make a careful drawing showing the digestive system 

 from aboral surface. 



10. Study the chart and your specimen to make out the 

 relations of the organs in side view. 



Reproduction 



The sexes are distinct. Have the gonads pointed out to 

 you. Number in each ray? Position, Form? Examine with 

 lens. Their ducts may be traced into the inter-radial partitions 

 whence they pass up to the openings on the upper surface of 

 the rays. Their external openings are very difficult to demon- 

 strate. 



Starfishes live only in the oceans where their germ cells 



