xii Contents. 



CHAPTER XXII. 



Pagh. 

 Class 3, Holothuroidea ; Order i, Apneumona Order 2, Tetra- 



pneumona ; Order 3, Dipneumona, 148 



CHAPTER XXIII. 



Sub-kingdom V. — Vermes. Province i, Archseostomata. Class i, 

 Turbellaria ; Order i, Dendrocoela ; Order 2, Rhabdoccela ; 

 Order 3, Nemertidea, 154 



CHAPTER XXIV. 



Class 2, Cotylidea ; Order i, Cestodea, 164 



CHAPTER XXV. 

 Order 2, Trematoda, - 172 



CHAPTER XXVI. 



Class 3, Nematelmia' Order i, Gordiaceoe ; Order 2, Nematoda, . 477 



CHAPTER XXVII. 



Class 4, Acanthocephala. Class 5, GephjTea ; Order i, Inermia ; 



Order 2, Armata, 187 



CHAPTER XXVIII. 



Class 6, Rotatoria; Order i, Gasterodela; Order 2, Holotrocha ; 



Order 3, Schizotroclia ; Order 4, Zygotrocha, .... 193 



CHAPTER XXIX. 



Class 7, Hirudinea. Class 8, Onychophora, 198 



CHAPTER XXX. . 



Province 2, Deuterostomata, Enteroccela. Class 9, Chaetognatha. 



Class 10, Enteropneusta, 206 



