258 QUESTIONS ON THE CCELENTERATA. 



12. Compare the Structure of the tentacles in 



a. Physalia; 



b. Forskalia; 



c. Apolemia. 



13. What is the position of the tentacles in the following genera of 



Hj'drozoa : 



a. Tubularia ; 



b. Hyclractinia •, 



c. Diphyes ; 



d. Porpita ; 

 €. Pelagia? 



14. Describe the ' pneumatocyst ' of any of the Physophoridae, and 



the principal modifications which it presents among other 

 genera of the same order. 



15. Describe, as to structm-e and position, 



a. the marginal ' vesicle ' of Geryonia ; 



b. the ' lithocyst ' of a free Lucernarid. 



16. How are the ' gonophores ' situated in the following genera of 



Corynidte : 



a. Tubularia; 

 , 6. Hydractinia ; 



c. Clavatella ; 



d. Cordylophora ? 



17. Compare the structural relations of the reproductive organs in 



a. Lucernaria; 



b. Aurelia; 



c. Rhizostoma. 



18. What are 'gonoblastidia'? Explain the modifications whicli 



these structures present among the Sertularidje. 



19. In what genera of Lucernaridae do free reproductive zooids 



occur ? Trace the development of any of these forms. 



20. Describe the development of a medusiform gonophore. 



21. Give some account of the early stages of development in 



a. Cordylophora lacustris ; 



b. Campanularia Loveni ; 



c. Cunina octonaria. 



22. What rule seems to govern the successive development of the 



appendages among the Physophoridae? 



23. Define the orders : 



a. Sertularidae ; 

 f). Calycophoridfe ; 

 c. Lucernaridfe. 



