354 QUESTIONS. 



32. Of what two essential elements is a Sponge composed ? 



33. What is the nature of the " sponge-flesh ? " 



34. Describe the circulation of water in a Sponge.. 



35. What are the chief variations in the skeleton of Sponges ? 



36. Whence are the Sponges of commerce obtained ? 



37. How do the Infusorian Animalcules derive their name ? 



38. By what leading character are the Infusoria distinguished from tlie 

 other Protozoa ? 



39. Why were the Infusoria formerly called Polygastrica ? 



40. Describe the Bell-animalcule. 



41. What peculiarity of the digestive system characterizes the sub-king- 

 dom Ccdenterata ? 



42. Of what is the body of a Coelenterate animal composed ? 



43. What is a " thread-cell ? " 



44. Into what two classes are the CceJenterata divided, and what charac- 

 ters distinguish these ? Mention examples of each. 



45. What is understood by " gemmation ? " How is a compound animal 

 or colony produced ? 



46. What is meant by the term " zooid ? " 



47. What is scientifically understood by the term " individual ? " 



48. Define the terms " polypite," " crenosarc," and " polypary." 



49. Give examples of the Hydroid Zoophytes. 



50. Describe shortly the structure of the Hydra. 



51. What is the method of reproduction in the Hydra ? 



52. What peculiarities distinguish the polypary of the Corynida . 



53. Give an example of the Corynida. 



54. What two sets of zooids go to form the colony of a Hydroid Zoo- 

 phyte? 



55. Define the terms " trophosome " and " gonosome." 



56. What is a " gonophore ? " 



57. What is a " medusiform gonophore ? " Why is it so called, and whai 

 is its general structure ? 



58. Give an example of the Sertularida, and mention the differences 

 which distinguish their polypary from that of the Cofynida. 



59. What is a "hydrothcca?" 



60. Describe the general structure of the reproductive bud of a Cam- 

 panularian. 



61. How do the Oceanic Hydrozoa differ from the Hydroid Zoophytes ? 



62. What is a " nectocalyx," and what is its structure ? 



63. What is a "bract?" 



64. Mention examples of the Oceanic Hydrozoa. 



65. What is the " float " or " pneumatophore " of the Physophoridce ? 



66. Of what real nature are many of the so-called Medusae or Jelly-fishes ? 



67. What is the general structure of a Medusa, and with what structure 

 in the Hydroid Zoophytes does it agree ? 



68. From what circumstance is the name " naked-eyed " Medusae derived ? 



69. What are the "marginal bodies " of the Medusce? 



70. Describe Lucernaria. 



71. Of what nature are the great Sea-blubbers ? 



72. Describe "Hydra-tuba" and its development. 



73. What is the structure of a " Hidden-eyed Medusa " or Sea-blubber, 

 and from what circumstance is the former name derived ? 



74. Differences between the naked-eyed and hidden-eyed Medusas ? 



75. Describe the generative bud of Khizostoma. 



