163. SHELLS OF TECTIBRANCHS 236 164. CHITON SHELLS 238 165. SHELLS OF _Dentalium_ 238 166. _Patellidæ_ 239 167. _Calyptræa sinensis_ 241 168. _Fissurellidæ_ 241 169. _Haliotis_ 242 170. _Ianthina fragilis_ 242 171. _Trochus zizyphinus_. 2. UNDER SIDE OF SHELL. 3. _Trochus magnus._ 4. _Adeorbis subcarinatus_ 244 172. _Rissoa labiosa_ AND _Lacuna pallidula_ 244 173. SECTION OF SHELL OF _Turritella_ 245 174. _Turritella communis_ AND _Cæcum trachea_ 245 175. _Cerithium reticulatum_ AND _Aporrhais pes-pelicani_ 245 176. _Aporrhais pes-pelicani_, SHOWING BOTH SHELL AND ANIMAL 246 177. 1. _Odostomia plicata._ 2. _Eulima polita._ 3. _Aclis supranitida_ 246 178. _Cypræa_ (_Trivia_) _europæa_ 247 179. 1. _Ovulum patulum_. 2. _Erato lævis_ 248 180. _Mangelia septangularis_ AND _Mangelia turricula_ 248 181. 1. _Purpura lapillus._ 2. EGG CASES OF _Purpura_. 3. _Nassa reticulata_ 249 182. _Murex erinaceus_ 249 183. OCTOPUS 251 184. _Loligo vulgaris_ AND ITS PEN 252 185. _Sepiola atlantica_ 252 186. _Sepia officinalis_ AND ITS 'BONE' 253 187. EGGS OF _Sepia_ 254 188. THE NERVE-CHAIN OF AN ARTHROPOD (LOBSTER) 257 189. SECTION THROUGH THE COMPOUND EYE OF AN ARTHROPOD 260 190. FOUR STAGES IN THE DEVELOPMENT OF THE COMMON SHORE CRAB 261 191. THE BARNACLE 261 192. FOUR STAGES IN THE DEVELOPMENT OF THE ACORN BARNACLE 262 193. A CLUSTER OF ACORN SHELLS 263 194. SHELL OF ACORN BARNACLE (_Balanus_) 263 195. THE ACORN BARNACLE (_Balanus porcatus_) WITH APPENDAGES PROTRUDED 264 196. A GROUP OF MARINE COPEPODS, MAGNIFIED 265 197. A GROUP OF OSTRACODE SHELLS 265 198. _Evadne_ 266 199. MARINE ISOPODS 267 200. MARINE AMPHIPODS 268