MOLLUSCA — PELECYPODS 219 



specimen should first be sectioned, then all the soft parts re- 

 moved except the muscles, soaked in corrosive sublimate for a 

 day or two, and thoroughly washed and dried.) 



5. What is the mantle ? Its function ? What mark does it 

 leave upon the shell ? 



6. What are the siphons? Their functions? What mark 

 does their presence make upon the shell and why ? 



7. Compare a transverse section of this pelecypod to a book. 



8. Explain in detail how respiration is effected. 



9. What does the clam eat ? Explain the process of getting 

 the food, its digestion and assimilation. 



10. Describe briefly the blood circulatory system. 



11. How are the different waste products of the body thrown 

 off? 



12. Of what does the nervous system consist? 



1 3 . Wha c sense organs does the clam possess ? Their function ? 



14. Name four sets of muscles, explaining the function of each. 



15. Describe in detail the growth of the shell. 



16. What is the origin of pearls ? 



17. Sketch the exterior of a valve, noting the umbo, beak, 

 growth Hues, lunule. 



18. Why are the growth lines arranged concentrically ? 



19. Explain the occurrence of the few strong growth lines 

 upon the shell. 



20. How can the mantle secrete three layers of shell ? 



21. Sketch interior of a valve, locating hinge margin, liga- 

 ment, hinge plate, teeth (cardinal and lateral), pallial Une, 

 pallial sinus, the two adductor and three foot muscles. 



22. What is the function of the teeth ? 



23. How is the foot protruded? 



24. What is the relation of the pallial sinus to the siphons ? 



25. How are the valves opened? How closed? Illustrate 

 with sketches. 



26. How do you distinguish the right from the left valve ? 



27. Are the two sexes united in one individual? 



28. Describe the development of the clam from the union 

 of spermatozoon and ovum to its adult state. 



General Survey of Class Pelecypoda 



Pelecypods are compressed, usually symmetrical, mollusks 

 protected by a calcareous shell of two, usually equal, valves 



