CONTENTS. xxiii 



Paragi-aph Page 



137 — 141. Vascular system 166 



142 — 145. Excretory organs 172 



146 — 156. Generative organs 178 



Fourth Section. Echinoderma, 



157- General review of the group 192 



Bibliography ........... 194 



158—161. Form of the body 194 



162. Appendages 199 



163 — 167. Integument and dermal skeleton 200 



168. Muscular system 207 



169. Nervous system 208 



170. Sensory organs .......... 210 



171 — 173. Alimentary canal 211 



174. Organs appended to the alimentary canal 215 



175. Coelom 216 



176. Vascular system 217 



Blood-vessels .......... 217 



177. 178. Water.vessels .219 



179. Excretory organs 224 



ISO. 181. Generative organs 224 



Fifth Section. Arthropoda, 



182. General review of the group . 228 



Bibliography 232 



183. Form of the body 234 



184. Appendages 237 



185. Appendages of the Branchiata ,..,... 238 



186. 187. Branchiae 240 



188—190. Appendages of the Tracheata 243 



191—193. Integument 248 



191. Muscular system 251 



195—200. Nervous system 252 



201. Sensory organs 260 



Tactile organs 260 



202. 203. Auditory organs 261 



204—206. Visual organs 263 



207—211. Alimentary canal 267 



212. Organs appended to the alimentary canal ..... 273 



1) Appendages of the fore -gut ...... 273 



213. 2) „ „ mid-gut 274 



214. 3) „ „ hind-gut 276 



215. Coelom 277 



216—220. Vascular system 279 



221. Excretory organs 285 



222—225. Traoheee 286 



226—237. Generative organs .... . ... 291 



