_Pylocheles_, 94 Pylochelidæ of deep sea, 136 Recapitulation, theory of, 86 Red-clawed Crayfish, 242 Regeneration in Lobster, 30 Relict faunas, 182 _Remipes_, 102 Reproduction of Cladocera, 166; of _Leptodora_, 169; of Cymothoinæ, 220 Reptantia, 59 Respiration in sand-burrowing Crabs, 99; in amphibious Crabs, 106; in Land Crabs, 193; in _Coenobita_, 195; in _Birgus_, 196; in Land Isopods, 201, 202, 203 Resting eggs of Cladocera, 166; of Copepoda, 170 Resting stage of Copepoda, 171 Reversal of asymmetry in Lobster, 30 Rhizocephala, 43; larvæ, 84; structure and development, 231 River Crabs: young of, 78; habits and distribution, 180; development of, 193 River Prawns, 179; used for food, 248 Robber Crab, 61, 94; habits and structure, 195; breeding, 199 Robertson, David, on habits of Crabs, 97 Rock Lobster. See Spiny Lobster Rostrum of Lobster, 6 _Sacculina_, 231 Salt lakes, Branchiopoda of, 165 Sand-burrowing Crustacea, 97 Sand-hoppers, 52; habits, 107, 189 _Sapphirina_, 150 Sargasso Sea, 155 Scampo, 240 _Scapellum_, fossil, 261 Scaphognathite, 19 Schizopod Stage of Lobster, 71; of _Penæus_, 75 _Scylla_, 249 Scyllaridæ, fossil, 269 Scyllaridea, 59; Phyllosoma larvæ, 149; fossil, 268 _Scyllarus_, fossil, 269 Sea-slater, 200 Sea-anemones: and Hermit Crabs, 213; carried by Crab, 215 Sea-crawfish. See Spiny Lobster Sea-urchin, Crab living in, 218 Sedentary Crustacea, 114 Self-mutilation in Lobster, 30 Senses of Lobster, 25 _Sergestes_, zoëa of, 75, 148 Serial homology, 10 _Sesarma_, habits, 180, 189 Sessile Barnacles, 43 Sexes of Lobster, 26 Sexual characters of Crabs infected with _Sacculina_, 235 Sharks, Barnacle parasitic on, 235 Shore Crab, 64; larval stages, 68; habits, 107, 188; infested by _Sacculina_, 231; used for food, 249 Shrimps, 58; fresh-water, 53, 172; Common, habits of, 97; protective resemblance, 108; living with Mollusc, 218; fishery, 244. See also Brown Shrimp, Pink Shrimp, etc. Sight, sense of, in Lobster, 21 Skeleton Shrimps, 109 Slaters, 51; Sea-, 200 Sloane, H., on Gulf-weed Crab, 155 Smell, sense of, in Lobster, 24 Smith, G.: on terrestrial Amphipoda, 189; on development of _Sacculina_, 233 Smith, S. I., on habits of _Ocypode_, 105 Somites of Lobster, 6, 8 Southern Crayfishes, 176 Spencer and Hall on Australian Branchiopoda, 161, 163 Sperm-receptacle of Lobster, 27 Spider Crabs, 64; masking habits, 96, 215; deep-sea, 128 Spiny Lobster, 59; larva of, 72; fishery, 240 _Spirontocaris_, Isopod parasitic on, 221 Sponge Crab, 95 Sponges, Crustacea in, 210 _Spongicola_, 210 _Squilla_, 64; larva of, 80; fossil, 266 Stalked Barnacles, 43