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. Chffitognatha, 44. 



Branch Trochelminthes . . .* 46 



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

 Gastrotricha, 47. 



Branch Molltjscoida 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. ChiPtopoda, 65.— Class II. Gcphyrca, 69.— Class III. 

 Hirudinea, 69. 



Branch Mollusca 72 



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

 Cephalopoda, 84. 



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