CONTENTS 



PAGE 



BRANCH PROTOZOA 1 



Class I. Rhizopoda, 1. Class II. Mastigophora, 4. Class III. 

 Sporozoa, 4. Class IV. Infusoria, 5. 



BRANCH PORIFERA 10 



BRANCH CCELENTERATA 17 



Class I. Hydrozoa, 18. Class II. The Scyphozoa, 26. Class 

 III. Actinozoa, 26. Class IV. Ctenophora, 31. 



BRANCH PLATYHELMINTHES '. . 34 



Class I. Turbellaria, 34. Class II. Trematoda, 35. Class III. 

 Cestoda, 37. Class IV. Nemertinea, 39. 



BRANCH NEMATHELMINTHES 41 



Class I. Nematoda, 41. Class II. Acanthocephala, 44. Class 

 III. Chaetognatha, 44. 



BRANCH TROCHELMINTHES 46 



Class I. Rotifera, 46. Class II. Dinophilea, 47. Class III. 

 Gastrotricha, 47. 



BRANCH MOLLUSCOIDA 48 



Class I. Polyzoa, 48. Class II. Phoronida, 48. Class III. 

 Brachiopoda, 48. 



BRANCH ECHINODERMATA 50 



Class I. Asteroidea, 54. Class II. Ophiuroidea, 56. Class III. 

 Echinoidea, 58. Class IV. Holothuroidea, 60. Class V. 

 Crinoidea, 62. 



BRANCH ANNULATA 65 



Class I. Cha3topoda, 65. Class II. Gephyrea, 69. Class III. 

 Hirudinea, 69. 



BRANCH MOLLUSCA 72 



Class I. Pelecypoda, 73. Class II. Gasteropoda, 81. Class III. 

 Cephalopoda, 84. 



v 



