xx LIST OF ILLUSTRATIONS 



FIG. PAGE 



1 06. Nereis dumerilii, natural size 189 



107. Nereis dumerilii, parapodium 190 



1 08. Nereis dumerilii, setae 191 



109. Nereis dumerilii, anatomy ....... 192 



no. Nereis dumerilii, transverse section ..... 194 



in. Section through the eye of Nereis 196 



112. Brain and connecting nerves of Nereis . . . . 197 



113. Serpuke in their tubes 198 



114. Trochosphere of Eupomatus 199 



115. Lumbricus agricola 200 



116. Lumbricus, setae 201 



117. Hirudo medicinalis 204 



118. Head of Hirudo medicinalis, showing the three jaws . . 205 



119. Head of Hirudo quinquestriata 206 



1 20. Nephridium of the medicinal leech 208 



121. Transverse section of Hirudo ...... 209 



122. Diagram of blood-channels of leech ..... 210 



123. Astacus fluviatilis 214 



124. Appendages of Astacus 217 



125. Astacus fluviatilis, dissection from right side . . .221 



126. Respiratory organs of Astacus fluviatilis .... 223 



127. Thorax of crayfish, transverse section 225 



128. Diagram of the circulation in the crayfish .... 226 



129. Nervous system of Astacus fluviatilis 227 



130. Reproductive organs of Astacus fluviatilis .... 229 



131. Cancer pagurus 230 



132. Pagurus bernhardus 231 



133. Apus glacialis 232 



134. Development of Apus 233 



135. Cyclops and Calocalanus 234 



136. Lepas anatifera 235 



137. Peripatus capensis ........ 237 



138. Peripatus capensis, head, etc. ...... 237 



139. Internal organs of Peripatus ...... 238 



140. Scolopendra 240 



141. Periplaneta americana 242 



142. Mouth-parts of the cockroach 243 



143. Pieris rapae, larva, and pupa 244 



