XX 



SCHEME OF THE CLASSIFICATION 



Phylum IV. CTENOPHORA 145 



Phylum V. PLATYHELMINTHES 



Class I. TURBELLARIA . 

 Order 1 . Rhabdoccelida 

 " 2. Tricladida . 

 u 3. Polycladida 



155 Class II. TREMATODA 



156 Order 1. Monogenea 



156 " 2. Digenea . 



157 Class III. CESTODA . 



150 



157 

 161 



161 



163 



Phylum VI. NEMATHELMINTHES . 



169 



GROUPS OF INVERTEBRATES OF MORE OR LESS 

 UNCERTAIN SYSTEMATIC POSITION .' 



7. Bryozoa . . 



8. Phoronidea 



9. Brachiopoda 

 10. Gephyrea . 



ry6 



181 



183 

 185 

 185 

 186 



Class I. ASTEROIDEA 

 Class II. OPHIUROIDEA 

 Class III. ECHINOIDEA 



)ERMATA . . . .189 



198 Class IV. HOLOTHURIOIDEA 205 



199 Class V. CRINOIDEA . . .208 

 202 



Phylum VIII. ANNELIDA 



Class I. ARCHI ANNELID A . 



Class II. CHJETOPODA . . 



Subclass I. Polychaeta . . 



Order 1. Phaneroceph- 



AL A. • • * 



