OrbiMdes, 52 



Orbitolites, 49 



Orectater, 140 



Orthis, 248 



Orthisina, 248 



Ortftoceras, 280, 281, 282, 284 



Orthoceratidte. 282, 284 



Orthopte-ra, 218 



Oscula, of Sponges, 55 of 



Tape-worms, 144 

 Ostracoda, 177 ; characters of, 



183 ; distribution of, iii time, 



196 



Ostrea, 255. 25fi 

 Ostreidce, 255, 256 

 Ovipositor, 210, 223 

 Ovulu/n, 266 



Paetil 



ru, 152 



ilopoda, 187 (see Xipho- 



Paguri</ce, 193 



Palceaster, 140 



Palcechinus, 140 



Pakeocorytie, 96 



Palueodiscus, 140 



Palceosponffia, />8 



Pali (Corals), 103 



Pallial line, 253 



Pallial sinus, 254 



Pallium (see Mantle) 



Paludiceltea, 239 



Paludina, 266, 283 



Palitdinidfe, 263, 266 



Paludomus, 266 



Palythoa, 104 



Pamphagus, 45 



Panopea, 257 



Panspermy, 33 



Pantopoda, 201 



Paramoecium. 59 ; structure of, 

 59 ; reproduction of, 60 



Parapodia. 160 



Parmacella, 267 



Parmophorwx. 266 



Parthenogenesis, 28-30 ; of Os- 

 tracode Crustacea, 183-185 ; 

 of Insects, 224 



Patella, 260, 266 



PaMlidce, 263, 266 



Pecten, 255, 256 



Pectunculus, 256 



Pedicellarii, 125 



Pedicellinece, 239 



Pediculus, 21 



Pedipalpi. 203 



Pelagia, 89 



Pelagidce. 88, 89 ; structure of 

 reproductive zocids of, 91 



Pelonaia, 229 



Pen of Cuttle-fishes, 274, 276 



Peniculus, 178 



Pennatula, 107 



Pennatulidce, 107, 105 ; distri- 

 bution of. in time, 119 



Pentacerotidce, 131 



Pentacrinus, 133, 134, 138, 139 



Pentantertts. 248 



Pentastomidn, 201 



Ptntatnma, 218 



Ptntremites, 130, 139 



INDEX. 



Perforate* (Foraminiffrd),^ ; 

 (Corals), 105, 119, 120 



Pericardium, of Crustacea, 171, 

 193 ; of JVautilut, 279 



Perid Tin, 77 



Peridinium, 64 



Peiigastric space of Polyzoa, 

 237 



Periostracum, 230 



Perischoechinuhc, 140 



Peristome. of Vorticella, 61 ; 

 of the shell of Gasteropoda, 

 261 



Peristomial space of Actinia. 

 99 



Peritoneum (Tunicata), 241 



Peri visceral space of ^Icft- 

 nozoa, 97 



Pet raster, 140 



Pftrotponffiadtff 58 



Phalangidoe, 202 



Pharynx of Ascidians, 241, 

 242 



Philine, 267 



Pfiillipsia, 196 



Pholadida-, 230, 256, 257 



Pholadomya, 257 



Phulas, 255, 258 



Phorus, 266 



Phosphorescence of the sea, 64 



Phragmacnne, 274 ; ofSpirula, 

 277 ; of Belemnite, 277 



Phragmoceras, 282 



Phryganeidce, 219 



PhylactoloBmata, 239 



Phyltidia. 267 



Phullidiadce, 264, 267 



Phyflirrhoe, 267 



Phyllirrhoidce, 264, 267 



Phyllocyst, 80 



Phyilopoda, 177 ; characters 

 of, 185 ; distribution of, in 

 time, 196 



Phyogeminaria, 83 



/ttgua, 268 



Physalia, 64, 67, 78, 82, 83 



lyiytaliadte, 84 



Physiology, 10 



Physophora, 83 



PhytophoridOK, 79, 82 ; tenta- 

 cles of, 82 ; reproduction 

 of, 83 ; distribution of, 96 



Pigment-spot, of Infusoria, 

 63 ; of Rotifera, 157 



Pileolus, 266 



Pileopsis, 266 



Pilidium, 150 



/Y/ma, 255, 256 



Pinnoctopus, 281 



Planar ida, 148, 149 



Planorbis. 261, 268 



Planula, 89 



Platyelmia, 141 



Pleura, of Lobster, 173; of 

 Trilobite, 187 



Pleurobrachiti, 111 ; cteno- 

 phores of, 111 ; canal- 

 system of, 112, 113; de- 

 velopment of, 113 ; homo- 

 logiesof, 113 



Pleitrobrqc/riadce, 114 



Pleurobmnchiada, 264, 267 



319 



Pleurobranchus, 267 

 Pleuronema, 64 

 Pleurotoma, 265 

 Pleurotomaria, 266 



P/umnster, 140 



Plumularia, 78 



teiw, 122 



Pneumatic filaments of PAy- 

 sophoridce, 82 



Pneumatocyst, 82 



Pneumatophore, 82, 83 



Pneumodermon, 269 



PodopMha/mata, 177 ; cha- 

 racters of, 191 



Podosoinata, 201 



Podura, 210, 217 



Polyarthra, 157 



Polyccelia, 119 



Polycystina, 53, 54 



Polydesmus, 207 



Polygastrica, of Ehrenberg, 60 



Polynoe, 166 



Polypary, 71 



Polype, 98 



Polypide, 234 



Polypidom, 234 



Polypi te, 68 



Polystome Infusoria, 64 



Polythalamia (Foraminifera) , 



Polt/trema, 51 



Polyzoa, 227, 228, 229 ; cha- 

 racters of, 232 ; distinctions 

 from Hydrozim, 232-234 ; 

 typical polypide of, 234 ; 

 avicularia of, 236 ; lopho- 

 phore of, 236 ; reproduc- 

 tion of, 238 ; development 

 of, 239 ; relations to ZV/wi- 

 Cflrto, 243 ; divisions of, 239 ; 

 distribution of, in space, 

 248 ; in time, 249 



Polyzoarium, 232, 234 



Pontobdella, 168 



Porambonites, 248 



Porcellanous shells, 230 



Porcellia, 283 



Pores of Sponges, 55 



Po/-/fe5, 118 



Poritidae, 120 



Potamides, 266 



Poulpe, 273, 275 



Praya, 80 



Prayidar, 82 



Prestitichia, 196 



Priapulacea, 160 



Proboscis, of Medusce, 85 ; of 

 Crinoidea, 134 ; of Plana- 

 rida, 149; of Acanthnce- 

 phala, 151 : of Gephyrea, 

 160; of Errantia, 166; of 

 Lepidoptera, 211 



Producta. 248 



Proditctidce, 248 



Prnglottis, 142, 145 



Pro-legs, 223 



Pro-ostracum, 277 



Propodite, 174 



Propodium, 259 



Proscolex, 143, 145 



Proxobranchiata, 262 ; divi- 

 sions of, 262, 263, 265 



