INDEX 



625 



a normal trilobite type, 1 27. 

 plain cephalon in, 157. 

 pleural spines in, 80. 

 Phaethonides, 174. 

 Phaetonella, 148. 

 Pharostoma, 154. 



glabella in, 154. 

 PMiipsia, 143, 148. 

 eyes in, 148. 



fixed-cheeks in, 127, 148. 

 glabella in, 148. 

 Phillipsinella, 146. 

 Pholidops, 231, 244. 

 ovalis, 315. 



pedicle-opening in, 241. 

 phrenism, 32. 



Phrynosoma, development of horns in, 

 47. 



extreme spinosity in, 70. 

 mimetic characters of, 63. 

 prickly scales of, 9. 

 phylembryo in Brachiopoda, 248. 



in trilobites, Jackson, 121. 

 Phyllocarida, 184. 



culmination of, 183. 

 development of anterior legs in, 84. 

 tail spine in, 84. 

 three spines in, 84. 

 Phyllopoda, 114, 184. 

 phyllopods, variation in nauplius of, 



191. 



Phyllopteryx eques, mimetic features of, 

 63. 



protective characters of, 55. 

 phylogeny of Avicula, Anomia, Spondy- 

 lus, 23. 



of spinous forms, 23. 

 of the Pelecypoda, Jackson, 23. 

 physiogenesis, 6. 



Physospongia Dawsoni, spiniform pro- 

 cess in, 50. 

 pipe-fish, 70. 



Australian, mimetic features of, Gun- 

 ther, 63. 

 protective characters of, Giin- 



ther, 55. 

 Fire, L., pathological varieties of recent 



Planorbis complanatus, 91. 

 Placocista spinosa, mitre-shaped form 



of, with numerous spines, 43. 

 Placoparia, 129, 153. 

 cephalon in, 154. 



Plcesiocomia, 154. 



glabella and pygidium in, 155. 

 Planorbis complanatus, pathological vari- 

 eties of recent, Pire, 91. 

 costatus, differentiation toward spi- 

 nosity in, 66. 

 pathological varieties of Steinheim, 



Hyatt, 91. 

 Steinheim, evolution of Tertiary 



species of, Hyatt, 65. 

 plants, climbing, general spininess of, 

 88. 



number of species of, Kerner, 



87. 

 suppression of structures in, 



87. 



defence in, Morris, 52. 

 desert, atrophy of leaves of, caused 

 by disuse, 82. 



differentiation of parts of, into 



spines, Henslow, 74. 

 spines in, 39, 71. 

 parasitic, spmiform scales in, 83. 

 primitive type of structure in, 26. 

 spineless young seedlings of, 19. 

 spiny varieties of, Henslow, 74. 

 thorny, decline of vitality in, 97. 

 xerophilous, origin of, Wallace 



and Henslow, 74. 



Platidia, 246, 288, 296, 300, 303, 307, 

 308. 



adult loop in, 291. 

 cistelliform stage in, 288, 302. 

 elimination of deltidial plates in, 



305. 



paragerontic tendency in, 271. 

 platidiform stage in, 298. 

 zugolophus stage in, 281. 

 Platyceras, 69. 

 Platymetopus, 150. 



glabella in, 150. 

 Platypeltis, 146. 

 Platystrophia, 245. 



biforata, 404, 405. 

 Plectambonites, 245, 256. 



absence of straight hinge-line in 



young, 268. 

 transversalis, 315. 

 plectolophus stage, 280, 284. 

 Pleurodictyum, 421, 422. 

 Aulopora stage in, 427. 

 lenticulare, casts of, 426. 



40 



