382 



INDEX. 



twig?, 64 ; females resembling 

 leaves, 112. 



PIIYLLIUM, wonderful protective 

 colour and form of, 64. 



PHYSALIA, 258. 



PIERID.E, local modification of 

 form in, 172. 



PIEKIS, females only imitating 

 Heliconidse, 112. 



Pier is coronis, 172; eperia, 172. 



Pieris pyrrha, 113. 



PICID.E, sexual colouring and nidi- 

 fication of, 242. 



PIPRID.E, sexual colouring and 

 nidification of, 245. 



PITTID^, 253. 



Pliocerus egualis, 101 ; P. elapoides, 

 P. euryzonus. 102. 



Pfsciloderma terminate, 93. 



POLARITY, Forbes' theory of, 17, 

 45. 



POLYMORPHISM, 145; illustration 

 of, 157. 



POPULATION of species, law of, 28 ; 

 does not permanently increase, 

 29; not determined by abun- 

 dance of offspring, 29; checks 

 to, 30 ; difference in the case of 

 cats and rabbits explained, 32. 



PREVISION, a case of, 122. 



PKIONITURUS, 196. 



PROTECTION, various modes in 

 which animals obtain it, 69-71, 

 258 ; greater need of, in female 

 insects and bird?, 113. 



PROTECTIVE colouring, theory of, 

 65. 



PSITTACI (Parrots), sexual colour- 

 ing and nidification of, 42. 



PTEROSAURIA, 298. 



PTYCIIODERES, 94. 



EACES, or subspecies, 160; of 

 man, origin of, 319. 



EEDBREAST and woodpigeon, pro- 

 tective colouring of, 53, 54. 



EEPRESENTATIVE groups, 9; of Tro- 

 gons, butterflies, &c., 12. 



EEPTILES, protective colouring of, 

 54. 



EIIAMPHASTID.E, sexual colouring 

 and nidification of, 242. 



EHIXOCEROS, 299. 



EIVER system, as illustrating self- 

 adaptation, 276. 



EOSES, Mr. Baker on varieties of, 

 165. 



EUDIMENTARY organs, 23. 



SALVIN, Mr. Osbert, on a case of 

 bird mimicry, 107. 



Saturn ia pavonia-minor, protective 

 colouring of larva of, 63. 



SATYRLD.E, probable means of pro- 

 tection of, 176. 



SAUROPTERYGIA, 299. 



SAVAGES, why they become extinct, 

 319 ; undeveloped intellect of, 

 339, 341 ; intellect of, compared 

 with that of animals, 341, 343; 

 protect their backs from rain, 

 346. 



SCANSORIAL birds, nests of, 238. 



SCAPIIURA, 98. 



SCISSIROSTRUM, 165. 



SCOPULIPEDES, brush-legged bees, 

 91. 



ScuDDER,Mr.,on fossil insects, 301. 



SCUTELLERID.E, mimicked by Long- 

 icorns, 96. 



Sesia bombiliformis, 90. 



SESUD.E, mimic Hymenoptera, 90. 



SEXES, comparative importance of, 



