INDKX. 



7*9 



dary, 487 ; obliteration of cavity of, 488 ; 

 comparative development of, 499; of 

 Lepidosteus and Teleostei, 499. See 

 also ' Eye ' 



Ora serrata, 488 



Orbitosphenoid region of skull, 570 



Organs, classification of, 391 ; derivation 

 of from germinal layers, 392 



Orycteropus, placenta of, 249 



Otic process of Axolotl, 583; of Frog, 

 585 et seq. 



Otoliths, 512 



Oviposition, of Amphioxus, i ; Elasmo- 

 branchii, 40; Teleostei, 68; Petromy- 

 zon, 84; Amphibia, 121; Reptilia, 202 



Ovum, of Amphioxus, i; Pyrosoma, 23; 

 Elasmobranchii, 40; Teleostei, 68; 

 Petromyzon, 83 ; Myxine, loo; Acipen- 

 ser, 102; Lepidosteus, in; Amphibia, 

 120; Chick, 146; Reptilia, 202 ; Mam- 

 malia, 214; of Porifera, 741; migra- 

 tion of in Ccelenterata, 742; Verte- 

 brata, 746 



Palatine bone, of Teleostei, 580; origin 

 of, 594 



Pancreas, Acipenser, no; general de- 

 velopment of, 770 



Pancreatic caeca, of Teleostei, etc. 768 



Papillae, oral, of Acipenser, 108; Lepi- 

 dosteus, n6 



Parachordals, 565, 566 



Parasphenoid bone, 594 



Parepididymis, 725 



Parietal bones, 592 



Paroophorori, 725 



Parovarium, 725 



Pectoral girdle, 599 ; of Elasmobranchs, 

 600; of Teleostei, 600; of Amphibia 

 and Amniota, 60 1 ; comparison of with 

 pelvic, 608 



Pecten, eye of, 479 



Pecten, of Ammoccetes, 498; of Chick, 

 501 ; Lizard, 501 ; Elasmobranchs, 501 



Pedicle, of Axolotl, 484 ; of Frog, 485 



Pelobates, branchial apertures of, 136; 

 vertebral column of, 556 



Pelodytes, branchial chamber of, 135 



Pelvic girdle, 606; of Fishes, 606; Am- 

 phibia and Amniota, 607 ; of Lacerti- 

 lia, 607 ; of Mammalia, 608 ; compari- 

 son with pectoral, 608 



Penis, development of, 727 



Peribranchial cavity, of Amphioxus, 7; 

 of Ascidia, 18; Pyrosoma, 24 



Pericardial cavity, of Pyrosoma, 26 ; Elas- 

 mobranchii, 49 ; Petromyzon, 94; gene- 

 ral account of, 626; of Fishes, 627 ; of 

 Amphibia, Sauropsida and Mammalia, 

 628 



Perichordal formation of vertebral column, 

 5^6 



Perilymph of ear, 523 

 Periotic capsules, ossifications in, 595, 

 596 



Peripatus, nervous system of, 409 ; eye of 

 480 ; excretory organs of, 688 



Peritoneal membrane, 626 



Petromyzon, development of, 83; affini- 

 ties of, 83, 84; general development 

 of, 87; hatching of, 89; comparison of 

 gastrula of, 280; branchial skeleton of, 

 312, 572; cerebellum of, 425; pineal 

 gland of, 434 ; pituitary body of, 436 ; 

 cerebrum of, 439; auditory organ of, 

 517; olfactory organ of, 533; compari- 

 son of oral skeleton of with Tadpole, 

 586; pericardial cavity of, 627; abdo- 

 minal pores of, 626 ; venous system of, 

 651 ; excretory organs of, 700; segmen- 

 tal duct of, 700; pronephros of, 700; 

 mesonephros of, 700 ; thyroid body of, 

 760; postanalgut of, 774; stomodx-um 



of, 775 



Phosphorescence of larvae, 364 



Phylogeny, of the Chordata, 327; of the 

 Metazoa, 384 



Pig, placenta of, 251; mandibular and 

 hyoid arches of, 589 



Pineal gland, of Petromyzon, 93 ; Chick, 

 175; general development of, 432; 

 nature of, 432, 434 



Pipa, brood-pouch of, 121 ; metamorpho- 

 sis of, 139; yolk-sack of, 140; vertebral 

 column of, 556 



Pituitary body, of Rabbit, 231 ; general 

 development of, 435 ; meaning of, 436 ; 

 Placenta, of Salpa, 29; Elasmobran- 

 chii, 66; of Mammalia, 232; villi of, 

 235 ; deciduate and non-deciduate, 239; 

 comparative account of, 239 259 ; cha- 

 racters of primitive type of, 240; zo- 

 nary, 248; non-deciduate, 250; histo- 

 logy of, 257; evolution of, 259 



Placoid scales, 395 



Planorbis, excretory organs of, 68 1 



Planula, structure of, 367 



Pleural cavities, 631 



Pleuronectidae, development of, 80 



Pneumatoccela, characters of, 327 



Polygordius, excretory organs of, 684 



Polyophthalmus, eye of, 479 



Polypedates, brood-pouch of, 121 



Polyzoa, excretory organs of, 682 ; gene- 

 rative cells of, 745 ; generative ducts 



of, 751 



Pons Varolii, 426, 427 



Pori abdominales, Ammoccetes, 99 



Porifera, ancestral form of, 345 ; develop- 

 ment of generative cells of, 74! 



Portal vein, 653 



Postanal gut of Elasmobranchii, 58, 59, 

 60; Teleostei, 75; Chick, 169; gene- 

 ral account of, 323, 772 



Prsemaxilla, 594 



Praeopercular bone, 593 



Prrcoral lobe, ganglion of, 377, 380 



Prefrontals, 597 



Presphenoid region of skull, 570 



Primitive groove of Chick, 1 55 



