ILLUSTRATIONS.
| The Rocky Shore at Low-water | Frontispiece |
| The Sandy Shore at Low-water | facing 11 |
| Foraminifera | 22 |
| Polycistin | 23 |
| Sponges | 29 |
| Section through Crumb-of-Bread Sponge | 32 |
| Grantia compressa | 35 |
| Grantia ciliata | 35 |
| Sea Oak Coralline | 39 |
| Calycles of Sertularia enlarged | 39 |
| Plumularia pinnata | 43 |
| Plumularian, portion enlarged | 43 |
| Haliclystus | 45 |
| Sea-Mat (Flustra) | 46 |
| Larvæ of Aurelia | 53 |
| Marigold (Aurelia aurita) | 54 |
| Portuguese Man o’ War | 56 |
| Tube-mouthed Sarsia | 57 |
| Forbes’ Æquorea | 58 |
| Beröe and Young | 61 |
| Beadlet | 65 |
| Snowy Anemone | 68 |
| Rosy Anemone | 68 |
| Orange-disk Anemone | 69 |
| Opelet | 73 |
| Dahlia Wartlet | 81 |
| Sun Star | 91 |
| Purple-tipped Urchin | 93 |
| Feather-star | 93 |
| Starlet | 93 |
| Granulate Brittle-star | 95 |
| Sipunculus | 103 |
| Sea-cucumber | 103 |
| Trumpet Sabella | 109 |
| Brush Sabella | 109 |
| Common Sabella | 109 |
| Scarlet Serpula | 113 |
| Pearly Nereis | 118 |
| Rainbow Leaf-worm | 119 |
| Banded Flat-worm | 125 |
| Long Worm | 125 |
| Zebedee (Xantho incisus) | 137 |
| Hairy-crab | 138 |
| Velvet Fiddler | 140 |
| The Hermit-crab and the Cloaklet Anemone | 145 |
| Scaly Squat-lobster | 148 |
| Broad-claw | 148 |
| Prickly Spider-crab | 152 |
| The Masked-crab (male) | 153 |
| Nut-crab | 157 |
| Angular-crab | 157 |
| The Prawn | 163 |
| Common Shrimp | 167 |
| Sea Slater | 173 |
| Ship-barnacle | 177 |
| Pyrgoma | 183 |
| Scalpellum | 183 |
| Porcate barnacle | 183 |
| Acorn-shell | 183 |
| Spiny Cockle | 186 |
| Banded Venus | 186 |
| Smooth Venus | 191 |
| Rayed Artemis | 192 |
| Cross-cut Carpet-shell | 193 |
| Common Scallops | 195 |
| Scallop hung up | 196 |
| Comb-shell | 198 |
| Rayed Trough-shell | 199 |
| Red-nosed Borer | 203 |
| Piddock | 203 |
| Limpets | 208 |
| Purples | 208 |
| Smooth Limpet | 211 |
| Smooth Limpet, thick variety | 211 |
| Netted Dog-whelk | 213 |
| Red Whelk | 214 |
| Cowry | 215 |
| Horn-shell | 218 |
| Pelican’s-foot | 220 |
| The Common Top | 221 |
| Violet-shell | 222 |
| Raft of Violet-shell | 222 |
| Slit Limpet | 223 |
| Hungarian Cap | 224 |
| Tusk-shell | 224 |
| Smooth Mail-shell | 225 |
| Sea Lemon | 226 |
| Crowned Eolis | 228 |
| Sea-hare | 229 |
| Sea-hare, front view | 230 |
| Octopus | 232 |
| Sepia | 234 |
| Squid (loligo) | 235 |
| Ascidia virginea | 237 |
| Cynthia quadrangularis | 237 |
| Diagrammatic section of an Ascidian | 238 |
| Orange-spotted Squirt (Cynthia aggregata) | 239 |
| Ascidia mentula | 240 |
| Currant-squirter (Styela grossularia) | 240 |
| Clavelina | 241 |
| Salpa maxima | 242 |
| Part of a chain of Salpæ | 242 |
| Botryllus | 243 |
| Botryllus violaceus | 244 |
| Larva of a Tunicate | 245 |
| Shanny | 247 |
| Father Lasher | 251 |
| Worm Pipe-fish | 251 |
| Little Goby | 257 |
| Butterfly Blenny | 257 |
| Corkwing Wrasse | 259 |
| Gunnel | 264 |
| Three-bearded Rockling | 266 |
| Fifteen-spined Stickleback | 267 |
| Lesser Weever | 267 |
| Two-spotted Sucker | 271 |
| Montagu’s Sucker | 273 |
| Topknot | 274 |
| Lesser Launce or Sand-eel | 275 |
| Shag | 279 |
| Solan Goose | 281 |
| Oyster Catcher | 281 |
| Razorbill | 285 |
| Puffin | 285 |
| Channelled Wrack | 289 |
| Bladder Wrack | 291 |
| Saw-edged Wrack | 291 |
| Pod-weed | 292 |
| Peacock’s Tail | 296 |
| Chondrus crispus | 299 |
| Ash-leaved Seaweed | 300 |