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, IS. — Class II. The Scyphozoa, 26. — Class 

 III. Aotinozoa, 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. Cheetognatha, 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 Anntjlata 65 



Class I. Chaetopoda, 65. — Class II. Gephyrea, 69. — Class III. 

 Hirudinea, 69. 



Branch Mollusca 72 



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

 Cephalopoda, 84. 



