LIST OF ILLUSTRATIONS. Xlll 



FIG. PAGE 



72. Life history of liver fluke (Thomas) 162 



73. Diagram of reproductive organs in Cestode joint (Leuckart) 166 



74. Life history of Tania solium (Leuckart) .... 167 



75. Diagrammatic longitudinal section of a Nemertean, Amphi- 



poms lactifloreus, dorsal view (M'Intosh) . . . 169 



76. Transverse section of a Nemertean, Drepanophorus latus 



(Burger) .... .... 171 



77. Transverse section of a simple Nemertean, Carinella (Burger) 172 



78. The structure of a Nematode, Oxyuris (Galeb) . . .176 



79. Trichinae in muscle, about to be encapsuled (Leuckart) . 179 



80. Do., encapsuled (Leuckart) . . 179 



81. Anterior region of earthworm (Hering) . 184 



82. Transverse section of earthworm (Claparede) . . 187 



83. Reproductive organs of earthworm (Hering) . .189 



84. Stages in the development of earthworm (Wilson) 191 



85. Arenicola marina ........ 195 



86. Anterior part of nervous system in Arenicola (Vogt and Yung) 196 



87. Dissection of lobnworm from dorsal surface . . . . 197 



88. Cross-section of Arenicola (Cosmovici) . . .198 



89. Development of Polygordius (Fraipont) . . . 201 

 89A. Parapodium of " Heteronereis " of Nereis pelagica (Ehlers) 203 



90. Free-living Polychjete, Nereis cultrifera . . . 205 



91. Transverse section of leech (Bourne) . . . 210 



92. Alimentary system of leech (Moquin Tandon) 211 



93. Dissection of leech (Bourne) . . 212 



94. Nephridium of leech (Bourne) . . 213 



95. Development of Sagitta (O. Hertwig) . . 217 



96. Actinotrocha or larva of Phoronis (Masterman) . . 220 



97. Interior of Brachiopod shell, showing calcareous support for 



the "arms" (Davidson) ...... 221 



98. Pluteus larva with rudiment of adult (Johannes Miiller) . 224 



99. Alimentary system of starfish (Miiller and Troschel) . . 227 



100. Diagrammatic cross-section of starfish arm (Ludwig) . . 229 



101. Ventral surface of disc of an Ophiuroid, Ophiothrix fragilis 



(Gegenbaur) .... . . 231 



102. Diagram of sea-urchin, Echinus (Huxley) .... 233 



103. Dissection of Holothurian, Holothuria tubulosa, from the 



ventral surface ... . . . 238 



104. Diagrammatic vertical section through disc and base of one 



of the arms of Antedon rosacea (Milnes Marshall) . . 240 



105. Stages in development of Echinoderms (Selenka) . . 242 



106. Appendages of Norway lobster . . . 253 

 io6a. Section of compound eye of Mysis vulgaris (Grenacher) . 254 

 io6b. A single eye element or ommatidium of the lobster (G. H. 



Parker) 255 



107. Longitudinal section of lobster, showing some of the organs 256 



108. Male reproductive organs of crayfish (Huxley) . . . 259 



109. Female reproductive organs of crayfish (Suckow) . . 260 

 no. Section through the egg of Astacus after the completion of 



segmentation (Reichenbach) .... .261 



