Pericardial fold, 376 



Pericardium, 1 1, 12. 14, 16. 345 



Pericardio-peritoneal foramen, 376 



Perichondral, 35 



Perichondrium, defined, 35 



Perichordal tube, 144. 148, 149, 150, 153 



Periderm, 221,224 



Perihemal space, 14 



Perilymphatic fenestra, 51, 61, 406 



Perilymphatic sac. 406 



Peril>-mphatic space, 406 



Periodontal membrane, 243 



Penopkthalmus, 225 



Peripheral nervous system, 387 



Perissodactyles. 22 



Peritoneal funnels. 293, 300, 310 



Pri\-itelline membrane, 194 



Perivitelline space, 194 



PnUidus, Perleididae, 20, 33, 115, 116 



Permian. 63. 88. 89, 115, 151, 233 



Peronaeus, brevis, 430 



longus, 430 



tertius, 430 

 Perpendicular fibers, 226 

 Pes. 178 



Petrodentine. 228 

 Petrolacosmms, 88, 89, 174, 178 

 Petromyzon, Petrom\-zontids, 18, 19, 23, 128, 



131, 139, 170. '278,55-^, 366 

 Petrosal. 38, 41. 46, 386 



dermal plate of. 49 

 Petrosal sinus, inferior, 360 



superior. 360 

 Phagocytic tissue, 314 

 Phalangeal formula, see digital formula 

 Phalanges, 171 

 Phaneropleuron, 169 

 Phary-ngeal artery, 354 

 PharvTigeal bars, 7 

 Phar>Tigeal blood vessels, 1 1 

 Pharyngeal branch of internal jugular, 360 

 PharNTigeal cavity, 196 

 Pharyngeal cilia, 8 

 Phar\Tigeal fenestrae, 197 

 Pharangeal openings, 12. 196 

 Pharangeal pouches, 289, 290, 380 



endocrine glands of, 381 

 Pharangeal sac. 16 

 Pharangeal sUts, 6, 11, 16 

 Pharyngobranchiai, 96, 107, 119 

 PharvTigocutaneous duct, 23, 289. 290 

 PharvTigoesophagus, 130, 275 

 Pharyngohyal, 122 

 PharyngoUpu, 137 

 Pharyngomandibula, 128 

 Par\'ngopremandibula, 128 

 Pharyngosuprahyal, 102, 112 

 Phar\n.\, 7. 11. 12. 16, 199, 201, 253, 256, 



289 

 Phascolarctus, 212 

 PhUboUpis, placoid scale, 231 

 Photoreceptor. 382 

 Photosensory cells. Hesse, 9 



Joseph. 9 



tunicate, 1 1 

 Photosensory organ, 406 

 Phoxinus, pearl organs, 226 



Phyllospondylous vertebrae, 155 



Phylogeny of svvim bladder, 237 



Phvlogenv of vertebrates. 446. 446. 447 



Physeler, 292 



Ph\-soch-stous, 284 



Ph\^ocl>-st, 285 



Phv'sostomous, 284 



Pig. 22, 212, 254, 291, 323, 364 



descent of testes. 320 



heart, development. 340 

 Pigment (of egg. frog). 199 

 Pigment cells. 218, 223, 226 

 Pigment laver, 226 

 Pika, 323 



Pila antotica, 76, 121, 122 

 Pila metoptica, 53, 54 

 Pila preoptica, 53, 54 

 Pineal evagination, 388 

 Pineal nerve, 388 

 Pineal organ, 382. 384. 405 

 PINKUS, 386 



Pin-tailed Tree Shrew. 254. 254 

 Pisiforme. 172, 173 

 Piston cartilage. 130 

 Pit lines, 410 

 Pit organs, 410 

 Pituitary, 379. 384 



origin in cyclostomes, 380 



pars anterior, 379 



pars intermedia, 379 



pars nervosa, 379 



pars tuberalis, 379 

 Placenta. 30, 208 



allantoic, 212 



chorio-allantoic, 212 

 lizard (TiUqua), 211 



cotyledonarv-, 212,213 



difRise, 212,213 



discoidal, 212, 2/5 



double discoidal, 213 



endotheliochorial type. 212 



epitheliochorial tv'pe, 212 



hemochorial type, 212 



incomplete zonary, 213 



of pig. 213 



svTidesmochorial type, 212 



t\pes seen in mammals, 213 



villi, 212 



yolk sac, AfusUlus, 211 

 Opossum, 212 



zonarv, 212, 213 

 Placental, 22, 30, 51, 57, 171, 294, 320, 384 

 Placoderms, 20, 126 



external appearance, 3/ 

 Placoid scale, 226, 233, 240 



development, 233 



of Squaltis, 228 

 Plagiostome, defined, 128 

 Planctosphaera, 5, 12, 19 

 Plantaris, 430 

 Platelets, 378 



Platypus, see OmithmhynchxLS 

 Platytrabic, 80 

 Pleistocene, 62 

 Plesodic fin, 240 



Plethodontidae ( Plethodontids), 281, 343, 

 344 



PleuTOcanthm, 31,3/, 183. 188 



Pleural caWties. 253. 280 



Pleurocentrum or hypocentrum. 162 



Pleurodont. 83, 249 



PieuTonecUs, 381 



Pleuropericardial folds. 280 



Pleuroperitoneal folds, 280 



Ple.xus or nerve net, 9 



PUddenrine, 228. 248 



PUocene, 62 



Ploioa^. 418 



Plume. 222 



Plumule, 222 



Pluriserial teeth, 248 



Pneumatic duct, 284 



Pneumatic skull, 72, 76 



Poison spur, 29 



Polar body. 193. 194 



Polar cartilage, 54. 107. 121, 128 



Polocyie, see polar body 



Polylobular kidney. 291. 292 



compact, 291 

 Polymorphonuclear cell, 377 

 Polyodon, 20, 24, 162, 181, 236, 269, 288, 307. 

 309,331.415 



digestive tract, 267 



external appearance, 25 



reproductive system, 332 



vertebrae, 162 

 Polyphalangv-, 175 

 Polyphyletic, 290 



origin of amphibia, 88 

 Po^-phyodont, 249 



PolypUrm, 21, 96, 115, 167, 181, 182, 188. 

 228, 236, 237, 238, 242, 271, 274. 275, 

 284, 285, 286, 288. 289. 290, 309. 329, 

 331, 332. 345, 350, 366, 394. 415 



digestive tract, 267, 268 



external anatomy, 26, 26 



fin base, 185 



ra«, 242, 243, 244 



head skeleton, development, 112 



kidney, 306 



development, 306 

 nephric duct, 307 

 pronephric crest, 307 



lana. 214 



pectoral girdle, 184 



reproductive system, 329, 332 



sensory -canal line s>-stem, development, 

 416 



vertebrae, 164 

 Pons, 385, 388 

 Ponteen flextire, 383 

 Popliteus, 430 

 Poracanthodes, 414 

 Poraspid, 137 

 Porcupine, 218 

 Pores, lateral-line. 25 



PoroUpis, Porolepids. or Porolepiformes, 21. 

 ICM. 241. 416 



head skeleton, 96 



scale, 241 

 Portal heart, 366, 376 

 Postanal gut, 372 



Postcaval vein, see posterior vena cava 

 Postcleithrum, 179, 181, 184 



472 • INDEX 



