INDEX. 



691 



Pieris, 496 



Pieris, cleavage of, 155 

 Pigeons, 26, 27, 614 

 Pigmented epithelium, 540 

 Pike, 576 

 Pilidium, 290, 291 

 Pill bug, 442 

 Pineal eye, 535 

 Pinealis, 535 

 Pinniped ia, 647 

 Pinnotheres, 437 

 Pinnulae, 340 

 Pin worm, 301 

 Pipa, 585, 588 

 Pipe fish, 578 

 Pisces, 557 

 Piscicola, 321 

 Pisidium, 368 

 Pituitary body, 535 

 Placenta, 634 

 Placentalia, 634 

 Placoid scale, 515, 558 

 Placophora, 356 

 Plagiaulax, 632 

 Plagiotremata, 597 

 Plagiostomi, 569 

 Planaria, 271 

 Planarians, 268 

 Planipennia, 482 

 Plankton, 179 

 Planorbis, 383 

 Plantigrade, 647 

 Plant lice, 490 

 Plants and animals, 171 

 Planula, 237 

 Plasma, blood, 88 

 Plasmic products, 64. 72 

 Plasmodium, 198, 21 6 

 Plastin, 66 

 Plastogamy, 184 

 Plastron, 594 

 Platanista, 645 

 Plathelminthes, 267 

 Platyonichus. 436, 437 

 Platyrrhinoe, 651 

 Plecoptera, 479 

 Plectognathi, 578 

 Pleistocene, 181 



Pleopoda, 401, 402 

 Plesiosauria, 594 

 Plethodon, 587 

 Pleura, 414, 462, 546 

 Pleuracanthus, 572 

 Pleural cavity, 546 

 Pleural cords, 354 

 Pleural ribs, 518 

 Pleurobrachia, 262, 264 

 Pleurocercoid, 283 

 Pleurodira, 596 

 Pleurodont teeth, 599 

 Pleuronectidae, 578 

 Pleuroperitoneal cavity, 546 

 Plictolophus, 616 

 Pliocene, 181 

 Pliohippus, 643 

 Pliny, 8 

 Plover, 615 

 Plumularia, 242 

 Plumatella, 324 

 Pluteus, 332 

 Pneumatic duct, 567 

 Pneumaticity of bones, 608 

 Pneumatophore, 243 

 Pneumodermon, 382 

 Pneumogastric nerve, 536 

 Podocoryne, 241 

 Podophrya, 68, 212 

 Podophthalmia, 427 

 Podura, 477 

 Poikilothermous, 115 

 Polar bodies, 146 

 Pole field, 263 

 Poles of egg, 147, 151 

 Polian vesicles, 331 

 Polistotrema, 557 

 Polybostrichus, 311 

 Poly ch setae, 311 

 Polychoerus, 269, 271 

 Polycladidea, 269, 271 

 Polyclinum, 510 

 Polyclonia, 247, 251 

 Polycystidse, 214 

 Polydesmidoe, 497 

 Polyergus, 488 

 Polygordius, 309. 314 

 Polymorphism, 165 



