260 QUESTIONS ON THE CCELENTERATA. 



46. Define the characters of the famil}- Beroidae, with reference to the 



subjoined categories : 



a. form of body ; 

 I. mouth ; 



c. canal system ; 



d. tentacles. 



47. Give some account of the distribution, bathy metrical and geo- 



graphical, of the reef- building Corals. 



48. What families of Zoantharia seem wholly extinct ? 



49. In what deposits does the family of Astraeidae first make its ap- 



pearance ? 



50. Name those groups of Corals which are most abundantly repre- 



sented in the Paleozoic series. 



