268 MOLLUSCA 



(1) Size? 



(2) Length? 



(c) The Stomach. 



(1) Size? 



(2) Shape? 



(3) Use? 



(d) The Intestines. Find their beginning at the poste- 



rior end of the stomach, trace them through the 

 heart, thence throughout the body. Are they 

 coiled or straight? 



(e) The Liver or Digestive Gland is lobed and surrounds 



the stomach. 



(1) Size? 



(2) Use? 



(f) The Excretory Organs are the kidneys or organs of 



Bojanus. These organs are dark colored and lie 

 near the pericardial cavity. 



(1) Size? 



(2) Use? 



(g) Sketch and name the digestive organs. 



(2) The Respiratory Organs, the gills, have been studied. 



(3) The Circulatory Organs. The heart may be seen to 



pulsate slowly in a specimen just opened. It is on 

 the dorsal side and may be seen through the mantle, 

 lying in the pericardial cavity. The heart consists 

 of the rather lengthy ventricle, through which runs 

 the intestine. The ventricle is joined by two lateral 

 thin-walled, triangular auricles which receive the 

 blood from the gills. The arteries carry the blood 

 to all parts of the body. 



(a) Identify and show your teacher the organs of circu- 



lation. 



(b) Sketch and name all parts. 



(4) The Nervous System is rather difficult for beginners, 



but may be made out in an alcoholic specimen. 



(a) Demonstrate to the teacher the following: The 



cerebral ganglia. Look between the labial palpi 



at their bases, identify these ganglia, and trace a 



nerve to the pedal ganglia in the foot near the 



