LIST OF ILLUSTRATIONS XI 



FIG. PAGE 



60. Anterior view of the internal organs of Lumbricus terrestris . 142 



61. Six segments from the intestinal region of Lumbricus 



terrestris, dissected so as to show the arrangement of the 



parts . 143 



62. Diagram of the anterior end of Lumbricus herculeus to show 



the arrangement of the nervous system . . . . 149 



63. Transverse section through Lumbricus terrestris in the region 



of the intestine and of a dorsal pore 151 



64. View of the reproductive organs of the earthworm, Lumbricus 



terrestris 154 



65. Nereis pelagica 158 



66. Transverse section through Nereis cultrifera . . . 159 



67. Hirudo medicinalis ........ 160 



68. View of the internal organs of Hirudo medicinalis . . 163 



69. Dissection of Sipunculus nudus . . . . . . 172 



70. The Common Crayfish, Astacus fluviatilis, seen from the side 177 



71. Astacus fluviatilis, viewed from beneath . . . . 178 



72. Left mouth-appendages of Astacus flumatilis . . . 183 



73. The Crayfish, Astacus flumatilis, split into two by a median 



cut extending along the mid-dorsal line and viewed from 



the side ] 90 



74. Diagrams to illustrate the process of " ecdy sis " in Arthropoda 1 94 



75. Male reproductive organs of Astacus fluviatilis . . . 195 



76. Female reproductive organs of Astacus flumatilis ... 195 



77. Dorsal view of a female Branchipus ..... 206 



78. Side viaw of male Simocephalus sima . . . . . 207 



79. Side view of female Simocephalus sima . ... . 207 



80. Lateral view of Cypris Candida 209 



81. Ventral view of a male Cyclops . . . . . . 210 



82. Dorsal view of a female Cyclops 211 



83. View of Lepas anatifera cut open longitudinally to show the 



disposition of the organs 213 



84. A Schizopod, Nyctiphanes norwegica ...... 216 



85. The Shore-crab, Carcinus maenas, ventral aspect . . 218 



86. Left side of a larva of the Prawn, Penaeus, to show the origin 



of the gills . . 219 



87. Female of Diastylis stygia, one of the Cumacea . . . 221 



88. The mouth appendages of Gammarus neglectus . . . 222 



89. Gammarus neglectus. Female bearing eggs seen in profile . 223 



90. Asellus aquaticus. Male viewed from above . . .' 224 



91. A Wood-louse, Porcellio scaber 224 



92. Peripatus capensis 225 



93. Peripatus capensis, male, dissected to show the internal 



organs 227 



94. A Centipede, Lithobius forficatus . . ... . . 229 



