LIST OF ILL USTRA TIONS. xiii 



FIG. PAGE 



60. Anterior region of earthworm. (HERING), . . 190 



6 1. Transverse section of earthworm. (CLAPARDE), . . 193 



62. Reproductive organs of earthworm. (HERING), . . 195 



63. Stages in the development of earthworm. (WlLSON), . 198 



64. Arenicola piscatorum. (CUNNINGHAM and RAMAGE), . 202 



65. Anterior part of nervous system in Arenicola. (VoGT and 



YUNG), ....... 203 



66. Dissection of anterior region of A renicola. (CosMOVici), . 204 



67. Cross section of A renicola. (CosMOVici), . . . 205 



68. Development of Polygordius. (FRAIPONT), . . 207 



69. Parapodium of a marine Polychsete, Heteronereis. (QuATRE- 



FAGES), ....... 210 



70. Transverse section of leech. (A. G. BOURNE), . . 217 



71. Dissection of leech, . . . . . .219 



72. Development of Sagitta. (O. HERTWIG), . . . 222 



73. Interior of Brachiopod shell, showing calcareous support for 



the "arms." (DAVIDSON), .... 226 



74. Pluteus larva with rudiment of adult. (JOHANNES MULLER), 228 



75. Alimentary system of starfish. (MULLER and TROSCHEL), 231 



76. Diagrammatic cross section of starfish arm. (LuDWio), . 233 



77. Ventral half of sea urchin. (TiEDEMANN), . . 238 



78. Dissection of Holothurian. ( HUNTER), . . . 242 



79. Diagrammatic vertical section through disc and base of one 



of the arms of Antedon rosaceus. (MiLNES MARSHALL), 245 



80. Stages in development of Echinoderms. (SELENKA), . 247 



81. Forms of Echinoderm larva. (MULLER), . . . 249 



82. Appendages of Norway lobster, .... 258 



83. A single eye element or ommatidium of the lobster. 



(PARKER), ..... 260 



84. Longitudinal section of lobster, showing some of the organs, 262 



85. Female reproductive organs of crayfish. (SucKOw), . 265 



86. Section through the egg of Astacus after the completion of 



segmentation. (REICHENBACH), . . . 266 



87. Longitudinal section of later embryo of Astacus. (REICH- 



ENBACH), ...... 267 



88. Embryo of crayfish, flattened out, with removal of yolk. 



(REICHENBACH), ...... 268 



89. Acorn shell (Balanus tintinnabuluni}. (DARWIN), . 273 



90. Development of Sacculina. (DELAGE), . . . 274 



91. Zoaea of common shore crab ( Carcinus mcsnas}. (FAXON), 281 



92. External form of Peripatus. (BALFOUR), . . . 286 



93. Dissection of Peripatus capensis. (BALFOUR), . . 288 



