258 QUESTIONS ON THE CCELENTERATA. 



12. Compare the structure of the tentacles in 



a. Physalia; 

 h. Forskalia; 

 c. Apoleraia. 



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



Hydrozoa : 



a. Tuhularia; 



b. Hydractinia ; 



c. Diphyes; 



d. Porpita; 



e. Pelagia? 



14. Describe the * pneumatocyst ' of any of the Physophoridse, and 



the principal modifications which it presents among other 

 genera of the same order. 



15. Describe, as to structure and position, 



a. the marginal ' vesicle ' of Geryonia ; 

 h. the 'lithocyst' of a free Lucernarid. 



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



Corynidae : 



a. Tubularia; 

 6. Hydi'actinia ; 



c. Clavatella; 



d. Cordylophora? 



17. Compare the structural relations of the reproductive organs m 



a. Lucernaria; 



b. Aurelia; 



c. Rhizostoma. 



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



these structures present among the Sertularidae. 



19. In what genera of Lucernaridai do free reproductive zobids 



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 Phy sophoridae ? 

 a3. Define the orders : 



a. Sertularidae; 



b. Calycophoridae ; 



c. Lucernaridae. 



