544 PRIMARY FACTORS OF ORGANIC EVOLUTION. 



Pike, 21. 



Pilsbry, 260. 



Pinnotheres holothuriae, 242. 



Pipilo erythrophthalmus, 52. 



Pisces, 87, 95, 98, 192, 195. 



Plagiaulacidae, 324, 345. 



Plagiaulax, 142. 



Plant variation, 23. 



Plants, fossil, 77; evolution of, 515. 



Platidia, 178, 179. 



Platypus, 135. 



Plectognathi, 106, 107, 108. 



Plectospondyli, 106. 



Plesiosauria, 114, 121. 



Pleuracanthus, 372. 



Pleuronectidae, 238. 



Plicatula, 267. 



Pliny, 227. 



Pliocene, 387. 



Plistocene, 149, 168. 



Podopterygia, 100. 



Poebotheriidae, 302. 



Pollard, 89. 



Polygamy, 390. 



Polymastodon, 142. 



Polymastodontidae, 324. 



Polynesians, 154. 



Polypedates, 68 ; P. quadrilineatus 



D. & B., 68. 



Polyprotodontia, 140, 143. 

 Polypterus, 89. 

 Polyzoa, 202. 

 Porifera, 80, 81. 

 Pouchet, 498. 

 Poulton ; E. B., 230, 237, 381, 392, 393, 



439, 449, 461- 



Pre-Carboniferous age, 421. 



Pressure, 286, 292, 295, 340, 405, 519. 



Principle of improvement, 527. 



Proal mastication, 318. 



Proboscidia, 128, 132, 133, 136, 141,144, 

 297, 305, 306, 309, 3i8, 321, 329, 330, 

 33L 332, 345- 36o, 382, 519. 



Procolophonina, 87, 88. 



Procyonidae, 48. 



Production of colors in lepidopterous 

 pupa?, 230. 



Prognathism, 417. 



Proportions of limbs and of their seg- 

 ments, 305. 



Prorastomus, 330. 



Protective colors, 392. 

 Proteida, 109, no, in. 

 Proteles. 146. 

 Proterotherium, 359. 

 Proterotome mastication, 318. 

 Proteus, 242. 

 Prothallium, 455. 

 Prothippus, 149, 359. 

 Protodonta, 388. 

 Protophyta, 75, 76, 77, 172. 

 Protoplasm, composition of, 483. 

 Prototheria, 88, 324 360, 374. 

 Protozoa, 75, 79, 81, 83, 172, 219, 249, 



252, 505- 

 Protozoon, 459. 

 Psalidodect mastication, 318. 

 Pseudis, 71. 

 Pseudosauria, 109. 

 Pseudosuchia, 116. 

 Psittacotherium, 329, 346, 351. 

 Ptenophus garruhts Smith, 73. 

 Pteridophyta, 77, 79. 

 Pterosauria, 115. 

 Ptilodus, 324. 



Puerco, 139, 140, 141, 147, 150, 156, 403. 

 Putorius ermineus, 50. 

 Pygopodidae, 123. 

 Pythonomorpha, 120. 

 Pyxicephalus, 71. 



Quadrumana, 132, 133, 136, 143, 293, 



294, 3o6, 326, 332, 360, 361, 467. 

 Quebec group, 413, 420. 

 Quenstedt, 189. 

 Quiscalus purpureus, 52. 



Rabl Riickard, 94. 



Raccoon pacing, 299. 



Rachitomi, 109, no, in, 372. 



Radiant energy, 484. 



Rana, agilis Thomas, 68 ; R. catesbey- 



ana, 68 ; R. chrysoprasina, 68 ; R. 



clamata, 68 ; R. hexadactyla, 68 ; R. 



temporaria, 64. 

 Ranidae, 65, 70, 71, 389. 

 Raphanus raphan^str^^)n L., 227; R. 



sativus L., 227. 

 Recapitulation, 453, 492. 

 Reduction of digits, 309. 

 Regeneration, 455. 

 Reptiles, degeneracy of the eye of 



