MOLLUSCA 399 



in the body structure of a starfish to change it to a sea-urchin? A sea- 

 urchin to a sea-cucumber? A sea-cucumber to a crinoid or sea-Hly? 



1 1 . Sequence of development and appearance of the classes of echinoderms? 

 ■See Geologic Distribution, Text, pp. 56, 60, 62, 64, and Fig. 302. 



12. Special characteristics of this branch. Of what interest are the 

 echinoderms to you? 



MOLLUSCA 



1. Body of Mollusca. — Segmented or unsegmented? Bilaterally sym- 

 metric or asymmetric? Covering? Defense? 



2. Variation in body plan and covering of the three classes of Mollusca? 

 o. Economic or commercial interest or value to man? 



4. Oysters or Pearls. — Which is of more commercial value to man? 



5. Name some molluscs that are solitary. Gregarious, ^^'hy? 



6. Name Mollusca found in your vicinity? Use? Harm? 



7. Locomotion. — What are the means and manner of locomotion in the 

 three classes of Mollusca? Rate? Name sluggish ones; active ones. 

 Why is the locomotion so slow? Compensation for this slowness? Ex- 

 ception: see Cuttlefishes, p. 84. 



8. Pearls. — Discuss the theory of their origin. Purpose to the mollusc? 

 To man? 



9. Shells. — How do you account for Mollusca developing such great 

 defensive armor? Advantages? Disadvantages to the branch? 



10. Affinities of molluscs and worms. See p. SS for a hint. 



11. "The molluscs are the most highly organized of any of the inver- 

 tebrates except the Arthropoda." Text, p. 87. Show the truth or falsity 

 of this statement, according to your own way of thinking. 



12. "Chambered Nautilus." — Read it and show how and why O. W. 

 Holmes has "immortalized" it. 



13. Structure and function of the molluscan body. See 16 under Worms, 

 and compare the two groups, system witii system. 



14. Compare the 7nind apparatus (nervous system and special senses) 

 and the mind manifestations of molluscs and worms. See Laboratory 

 Guide, pp. 12-16, Animal Behavior. 



15. Mind Type.— Sluggish or alert? (Cuttlefishes, p. 84.) 



16. Body Type. — Sluggish or alert? (Squid, p. So.) 



17. Does the body-type make the mind-type, or vice versa? 



18. Name the one great specialization of the mollusc as to: (1) its bodj^; 

 (2) its mind manifestations. 



19. Dominance as a branch of the animal world. Is it persistent geo- 

 logically? 



20. Summary of the molluscan branch and its classes, past and present 

 (geologically). 



