INDEX 



457 



Intestines, regions of, 20. 



— convolutions, 21, 



— peculiarities of, 21. 



— and adaptation, 435. 

 Intraorganismal selection, 333. 

 Isolation areas, Mgnificance of, 79. 



— and evolution, 354. 



variation, 355. 



fixity of type, 361. 



— indiscriminate, 357. 



K 



Kea, killing sheep, 114. 



Lungs, structure of, 17. 



M 



Madagascar, extinct birds of, 6g. 

 Megapodes, nest of, 217, 218, 248. 

 Melanism, 308. 

 Migration, seasonal, gi. 



— routes, 92. 



— altitude during, 95. 



— and lighthouses, 97. 



— causes of, 99. 



— interpretation of, 103. 



— and geographical races, 104. 

 Mimicry, 327. 



Moult, forms of, 279. 



Muscular system, peculiarities of, 26, 



27. 

 Mutations, 303. 



N 



Natural selection and evolution, 356. 

 Nearctic region, confines of, 74. 

 Neossoptyles, 11, 271. 

 Neotropical region, birds of, 75. 

 Nervous system, 27. 

 Nestling down, 10, 11, 271. 



— bright colours in, 233. 



— conditions of, at hatching, 235. 



— development of, 243. 



— wings of, 244. 



Nests as receptacles for nests, 126. 



— types of, 176 et seq. 



— origin of, 194. 

 Night-jars, evolution of, 440. 

 Nutcracker, irruption of, 99. 

 Nuthatch, peculiar distribution, 78. 



29* 



O 



Offspring, care of, 223. 

 Oil-gland, use of, 15, 16. 

 Organs of extreme perfection, 404. 

 Ostriches and Zebras, 124. 

 Owls and vole plague, 113. 



— changed nesting habits of, 117. 



— mutational form of, 303. 



— asymmetrical ears of, 369. 



— evolution of, 439. 

 Oxpecker and cattle, 124. 



Palate, avian, peculiarities of, 43, 46. 

 Pallas's Sand-grouse, irruption of, 98. 

 Parasitism, 127. 

 Passeres, characters of, 56. 



— descent of, 60. 



Pelvic girdle, peculiarities of, 33, 383, 

 385, 389- 



— limb, peculiarities of, 34, 

 Penguins, descent of, 48. 



— southern origin of, 77. 



— paddle of, 385. 

 Petrels, descent of, 48. 



— lamellated beaks of, 50. 



— convergence in, 448. 



— transformation qfc 454- 

 Pheasants, distributimial centre of, 70. 

 Physiological selection, 357. 

 Pigeon, passenger, vast hordes of, 135. 

 Pigeons, descent of, 55, 56. 



— domestic, evolution of, 335. 

 Play of birds, 290. 



Plovers, forms of, 53-55. 



Plumage, effect of weathering on, 80. 



— disintegration of, 80. 



— intensification of colour in, 81. 



— bleaching in, 81, 82. 



— effect of moisture on, 82. 



— winter whitening of, 84. 



— displays of, 144. 



— phases of, 269, 271, 276. 



— " eclipse," 277. 

 Powder-down, 11. 

 Prepennae, 10, 271. 

 Preplumulse, 10, 271. 

 Pro-aves, characters of, 38. 

 Pterylosis, 12. 

 Pygostyle, structure of, 266. 



— peculiarities of, 399. 



Quails, primitive coloration of, 259. 

 — rapid maturity of, 269. 



