xii Contents. 



CHAPTER XXII. 



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



pneumona ; Order 3, Dipneumona, . . . . . .148 



CHAPTER XXIII. 



Sub-kingdom V. Vermes. Province I, Archaeostomata. Cl. 



Turbellaria; Order I, Dendrocoela ; Order 2, Rhabdoccela ; 

 Order 3, Nemertidea, ........ I ^ I 



CHAPTKR XXIV. 



Class 2, Cotylidea; On! lea, ...... i' i 



CHAPTER XXV. 



Order 2, Trematoda, ......... . 172 



CHAPTER XXVI. 

 ria-> 3, Xcmatelmia Order I, Gordiacere ; Order 2, Xematoda, . 477 



CHAPTER XXVII. 



Class 4, Acanthocephal hyrea ; Order i, Inermia : 



Order 2, Armata, ......... 187 



CHAPTER XXVIII. 



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



Order 3, Schizotrocha ; Order 4, Zygotrocha, . . . .103 



CHAPTER XXIX. 



Class 7, Hirudinea. Class 8, Onychophora, ..... iqS 



CHAPTER XXX. 



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



Class 10, Enteropneusta, ........ 206 



