XVlll LIST OF ILLUSTRATIONS 



FIG , PAGE 



159. Dissection of A sterias rubens. From a specimen . . 294 



160. Diagrammatic cross-section of starfish arm — after Ludwig . 296 



161. Regeneration of a starfish from a separated arm — so-called 



" comet form "....,. 297 



162. Ventral surface of disc of an Ophiuroid {Ophiothrix fragilis) 



— after Gegenbaur . . . . . .299 



163. Apical disc of sea-urchin . . . . . 301 



164. Dissection of sea-urchin ...... 302 



165. Spicules of Holothurians — after Semon . . . 306 



166. A small sea-cucumber ...... 307 



167. Dissection of Holothurian {Holothuria tuhulosa) from the 



ventral surface ...... 309 



168. Diagrammatic vertical section through disc and base of one 



of the arms of Antedon rosacea — after Milnes Marshall . 311 



169. General appearance of a stalked Crinoid (P^n/acnmfs) . 313 



170. Stages in development of Echinoderms — after Selenka . 316 



171. Appendages of Norway lobster ..... 324 



172. Central nervous system of the crayfish . . . 325 



173. Section of compound eye of Mysis vulgaris — after Grenacher 326 



174. An ommatidium of a compound eye . . . .327 



175. Longitudinal section of lobster, showing some of the organs . 329 



176. Male reproductive organs of crayfish — after Huxley . 332 



177. Female reproductive organs of crayfish — after Suckow . 333 



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



segmentation — after Reichenbach . . -334 



179. Longitudinal section of later embryo of Astacus — after 



Reichenbach ...... 335 



180. Section through cephalothorax of a crab — after Pearson . 336 



181. Dorsal aspect of swimming crab (Portunus) . . . 337 



182. Dorsal aspect of shore crab (Carcinus). . . . 337 



183. Ventral aspect of female shore crab .... 338 



184. Dorsal surface of Apus cancriformis — from Bronn's 



" Thierreich "...... 339 



185. Daphnia . . . . . . . .341 



186. Cypris ........ 342 



187. Cyan's, side view, after removal of one valve — after Zenker . 342 



188. Cyclops type ....... 343 



189. Two barnacles hanging from a ship / . . . 344 



190. Acorn-shell [Balanus tintinnabulum) — after Darwin . . 346 



191. Development of Sacculina — after Delage. (Not drawn to 



scale) ....... 347 



192. Sacculina as a parasite on a female crab — after Delage . 348 



